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SINGLE CHANNEL T1/E1/J1 LONG HAUL/ SHORT HAUL LINE INTERFACE UNIT PRELIMINARY IDT82V2081 FEATURES: * * * * * * Single channel T1/E1/J1 long haul/short haul line interfaces Supports HPS (Hitless Protection Switching) for 1+1 protection without external relays Receiver sensitivity exceeds -36 dB@772KHz and -43 dB@1024 KHz Programmable T1/E1/J1 switchability allowing one bill of material for any line condition Single 3.3 V power supply with 5 V tolerance on digital interfaces Meets or exceeds specifications in - ANSI T1.102, T1.403 and T1.408 - ITU I.431, G.703,G.736, G.775 and G.823 - ETSI 300-166, 300-233 and TBR12/13 - AT&T Pub 62411 Software programmable or hardware selectable on: - Wave-shaping templates for short haul and long haul LBO (Line Build Out) - Line terminating impedance (T1:100 , J1:110 , E1:75 /120 ) - Adjustment of arbitrary pulse shape - JA (Jitter Attenuator) position (receive path or transmit path) - Single rail/dual rail system interfaces - B8ZS/HDB3/AMI line encoding/decoding Active edge of transmit clock (TCLK) and receive clock (RCLK) Active level of transmit data (TDATA) and receive data (RDATA) Receiver or transmitter power down High impedance setting for line drivers PRBS (Pseudo Random Bit Sequence) generation and detection with 215-1 PRBS polynomials for E1 - QRSS (Quasi Random Sequence Signals) generation and detection with 220-1 QRSS polynomials for T1/J1 - 16-bit BPV (Bipolar Pulse Violation) /Excess Zero/PRBS or QRSS error counter - Analog loopback, Digital loopback, Remote loopback and Inband loopback Cable attenuation indication Adaptive receive sensitivity Short circuit protection and internal protection diode for line drivers LOS (Loss Of Signal) & AIS (Alarm Indication Signal) detection Supports serial control interface, Motorola and Intel Multiplexed interfaces and hardware control mode Package: IDT82V2081: 44-pin TQFP - * * * * * * * DESCRIPTION: The IDT82V2081 can be configured as a single channel T1, E1 or J1 Line Interface Unit. In receive path, an Adaptive Equalizer is integrated to remove the distortion introduced by the cable attenuation. The IDT82V2081 also performs clock/data recovery, AMI/B8ZS/HDB3 line decoding and detects and reports the LOS conditions. In transmit path, there is an AMI/ B8ZS/HDB3 encoder, Waveform Shaper and LBOs. There is one Jitter Attenuator, which can be placed in either the receive path or the transmit path. The Jitter Attenuator can also be disabled. The IDT82V2081 supports both Single Rail and Dual Rail system interfaces. To facilitate the network maintenance, a PRBS/QRSS generation/detection circuit is integrated in the chip, and different types of loopbacks can be set according to the applications. Four different kinds of line terminating impedance, 75 , 100 , 110 and 120 are selectable. The chip also provides driver short-circuit protection and internal protection diode. The chip can be controlled by either software or hardware. The IDT82V2081 can be used in LAN, WAN, Routers, Wireless Base Stations, IADs, IMAs, IMAPs, Gateways, Frame Relay Access Devices, CSU/DSU equipment, etc. INDUSTRIAL TEMPERATURE RANGES 1 2003 Integrated Device Technology, Inc. All rights reserved. Product specification is subject to change without notice. The IDT logo is a registered trademark of Integrated Device Technology, Inc. APRIL 2003 DSC-6228/1 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES FUNCTIONAL BLOCK DIAGRAM LOS RCLK RD/RDP CV/RDN LOS/AIS Detector B8ZS/ HDB3/AMI Decoder PRBS Detector IBLC Detector Data and Clock Recovery Data Slicer Adaptive Equalizer Receiver Internal Termination Analog Loopback Transmitter Internal Termination TTIP TRING RTIP RRING Jitter Attenuator Remote Loopback Digital Loopback Waveform Shaper/LBO Line Driver TCLK TD/TDP TDN B8ZS/ HDB3/AMI Decoder PRBS Generator IBLC Generator TAOS Clock Generator Jitter Attenuator Software Control Interface Register Files Pin Control SDO / ACK / RDY RD / DS / SCLKE SDI/ WR /R/W SCLK/ALE/AS Figure-1 Block Diagram 2 MODE[1:0] TERM RXTXM[1:0] PULS[3:0] EQ PATT[1:0] JA[1:0] MONT LP[1:0] THZ RCLKE RPD RST VDDIO VDDD VDDA VDDT MCLK CS AD[7:0] INT SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES TABLE OF CONTENTS 1 2 3 IDT82V2081 PIN CONFIGURATIONS .......................................................................................... 8 PIN DESCRIPTION ....................................................................................................................... 9 FUNCTIONAL DESCRIPTION .................................................................................................... 15 3.1 CONTROL MODE SELECTION ....................................................................................... 15 3.2 T1/E1/J1 MODE SELECTION .......................................................................................... 15 3.3 TRANSMIT PATH ............................................................................................................. 15 3.3.1 TRANSMIT PATH SYSTEM INTERFACE.............................................................. 15 3.3.2 ENCODER ............................................................................................................. 15 3.3.3 PULSE SHAPER .................................................................................................... 15 3.3.3.1 Preset Pulse Templates .......................................................................... 15 3.3.3.2 LBO (Line Build Out) ............................................................................... 16 3.3.3.3 User-Programmable Arbitrary Waveform ................................................ 16 3.3.4 TRANSMIT PATH LINE INTERFACE..................................................................... 20 3.3.5 TRANSMIT PATH POWER DOWN ........................................................................ 21 3.4 RECEIVE PATH ............................................................................................................... 21 3.4.1 RECEIVE INTERNAL TERMINATION.................................................................... 21 3.4.2 LINE MONITOR ...................................................................................................... 22 3.4.3 ADAPTIVE EQUALIZER......................................................................................... 22 3.4.4 RECEIVE SENSITIVITY ......................................................................................... 22 3.4.5 DATA SLICER ........................................................................................................ 22 3.4.6 CDR (Clock & Data Recovery)................................................................................ 22 3.4.7 DECODER .............................................................................................................. 22 3.4.8 RECEIVE PATH SYSTEM INTERFACE ................................................................ 22 3.4.9 RECEIVE PATH POWER DOWN........................................................................... 23 3.5 JITTER ATTENUATOR .................................................................................................... 23 3.5.1 JITTER ATTENUATION FUNCTION DESCRIPTION ............................................ 23 3.5.2 JITTER ATTENUATOR PERFORMANCE ............................................................. 23 3.6 LOS AND AIS DETECTION ............................................................................................. 23 3.6.1 LOS DETECTION ................................................................................................... 23 3.6.2 AIS DETECTION .................................................................................................... 25 3.7 TRANSMIT AND DETECT INTERNAL PATTERNS ........................................................ 26 3.7.1 TRANSMIT ALL ONES ........................................................................................... 26 3.7.2 TRANSMIT ALL ZEROS......................................................................................... 26 3.7.3 PRBS/QRSS GENERATION AND DETECTION.................................................... 26 3.8 LOOPBACK ...................................................................................................................... 26 3.8.1 ANALOG LOOPBACK ............................................................................................ 26 3.8.2 DIGITAL LOOPBACK ............................................................................................. 27 3.8.3 REMOTE LOOPBACK............................................................................................ 27 3.8.4 INBAND LOOPBACK.............................................................................................. 28 3.8.4.1 Transmit Activate/Deactivate Loopback Code......................................... 28 3.8.4.2 Receive Activate/Deactivate Loopback Code.......................................... 28 3.8.4.3 Automatic Remote Loopback .................................................................. 28 3 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 4 ERROR DETECTION/COUNTING AND INSERTION ...................................................... 29 3.9.1 DEFINITION OF LINE CODING ERROR ............................................................... 29 3.9.2 ERROR DETECTION AND COUNTING ................................................................ 29 3.9.3 BIPOLAR VIOLATION AND PRBS ERROR INSERTION ...................................... 30 LINE DRIVER FAILURE MONITORING ........................................................................... 30 MCLK AND TCLK ............................................................................................................. 30 3.11.1 MASTER CLOCK (MCLK) ...................................................................................... 30 3.11.2 TRANSMIT CLOCK (TCLK).................................................................................... 30 MICROCONTROLLER INTERFACES ............................................................................. 31 3.12.1 PARALLEL MICROCONTROLLER INTERFACE................................................... 31 3.12.2 SERIAL MICROCONTROLLER INTERFACE ........................................................ 31 INTERRUPT HANDLING .................................................................................................. 31 5V TOLERANT I/O PINS .................................................................................................. 32 RESET OPERATION ........................................................................................................ 32 POWER SUPPLY ............................................................................................................. 32 PROGRAMMING INFORMATION .............................................................................................. 33 4.1 REGISTER LIST AND MAP ............................................................................................. 33 4.2 REGISTER DESCRIPTION .............................................................................................. 34 4.2.1 CONTROL REGISTERS......................................................................................... 34 4.2.2 TRANSMIT PATH CONTROL REGISTERS........................................................... 35 4.2.3 RECEIVE PATH CONTROL REGISTERS ............................................................. 37 4.2.4 NETWORK DIAGNOSTICS CONTROL REGISTERS ........................................... 39 4.2.5 INTERRUPT CONTROL REGISTERS ................................................................... 42 4.2.6 LINE STATUS REGISTERS ................................................................................... 45 4.2.7 INTERRUPT STATUS REGISTERS ...................................................................... 47 4.2.8 COUNTER REGISTERS ........................................................................................ 48 HARDWARE CONTROL PIN SUMMARY .................................................................................. 49 TEST SPECIFICATIONS ............................................................................................................ 51 MICROCONTROLLER INTERFACE TIMING CHARACTERISTICS ......................................... 62 7.1 SERIAL INTERFACE TIMING .......................................................................................... 62 7.2 PARALLEL INTERFACE TIMING ..................................................................................... 63 5 6 7 4 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES LIST OF TABLES Table-1 Table-2 Table-3 Table-4 Table-5 Table-6 Table-7 Table-8 Table-9 Table-10 Table-11 Table-12 Table-13 Table-14 Table-15 Table-16 Table-17 Table-18 Table-19 Table-20 Table-21 Table-22 Table-23 Table-24 Table-25 Table-26 Table-27 Table-28 Table-29 Table-30 Table-31 Table-32 Table-33 Table-34 Table-35 Table-36 Table-37 Table-38 Table-39 Table-40 Table-41 Table-42 Table-43 Table-44 Table-45 Table-46 Pin Description ................................................................................................................ 9 Transmit Waveform Value For E1 75 ........................................................................ 17 Transmit Waveform Value For E1 120 ...................................................................... 17 Transmit Waveform Value For T1 0~133 ft................................................................... 17 Transmit Waveform Value For T1 133~266 ft............................................................... 18 Transmit Waveform Value For T1 266~399 ft............................................................... 18 Transmit Waveform Value For T1 399~533 ft............................................................... 18 Transmit Waveform Value For T1 533~655 ft............................................................... 18 Transmit Waveform Value For J1 0~655 ft ................................................................... 19 Transmit Waveform Value For DS1 0 dB LBO.............................................................. 19 Transmit Waveform Value For DS1 -7.5 dB LBO ......................................................... 19 Transmit Waveform Value For DS1 -15.0 dB LBO ....................................................... 19 Transmit Waveform Value For DS1 -22.5 dB LBO ....................................................... 20 Impedance Matching for Transmitter ............................................................................ 20 Impedance Matching for Receiver ................................................................................ 21 Criteria of Starting Speed Adjustment........................................................................... 23 LOS Declare and Clear Criteria for Short Haul Mode ................................................... 24 LOS Declare and Clear Criteria for Long Haul Mode.................................................... 25 AIS Condition ................................................................................................................ 25 Criteria for Setting/Clearing the PRBS_S Bit ................................................................ 26 EXZ Definition ............................................................................................................... 29 Interrupt Event............................................................................................................... 32 Register List and Map ................................................................................................... 33 ID: Device Revision Register ........................................................................................ 34 RST: Reset Register ..................................................................................................... 34 GCF: Global Configuration Register ............................................................................. 34 TERM: Transmit and Receive Termination Configuration Register .............................. 34 JACF: Jitter Attenuation Configuration Register ........................................................... 35 TCF0: Transmitter Configuration Register 0 ................................................................. 35 TCF1: Transmitter Configuration Register 1 ................................................................. 36 TCF2: Transmitter Configuration Register 2 ................................................................. 36 TCF3: Transmitter Configuration Register 3 ................................................................. 37 TCF4: Transmitter Configuration Register 4 ................................................................. 37 RCF0: Receiver Configuration Register 0..................................................................... 37 RCF1: Receiver Configuration Register 1..................................................................... 38 RCF2: Receiver Configuration Register 2..................................................................... 39 MAINT0: Maintenance Function Control Register 0...................................................... 39 MAINT1: Maintenance Function Control Register 1...................................................... 40 MAINT2: Maintenance Function Control Register 2...................................................... 40 MAINT3: Maintenance Function Control Register 3...................................................... 40 MAINT4: Maintenance Function Control Register 4...................................................... 41 MAINT5: Maintenance Function Control Register 5...................................................... 41 MAINT6: Maintenance Function Control Register 6...................................................... 41 INTM0: Interrupt Mask Register 0 ................................................................................. 42 INTM1: Interrupt Masked Register 1 ............................................................................. 43 INTES: Interrupt Trigger Edge Select Register ............................................................. 44 5 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES Table-47 Table-48 Table-49 Table-50 Table-51 Table-52 Table-53 Table-54 Table-55 Table-56 Table-57 Table-58 Table-59 Table-60 Table-61 Table-62 Table-63 Table-64 Table-65 Table-66 Table-67 Table-68 Table-69 STAT0: Line Status Register 0 (real time status monitor)............................................. STAT1: Line Status Register 1 (real time status monitor)............................................. INTS0: Interrupt Status Register 0 ................................................................................ INTS1: Interrupt Status Register 1 ................................................................................ CNT0: Error Counter L-byte Register 0......................................................................... CNT1: Error Counter H-byte Register 1 ........................................................................ Hardware Control Pin Summary ................................................................................... Absolute Maximum Rating ............................................................................................ Recommended Operation Conditions ........................................................................... Power Consumption...................................................................................................... DC Characteristics ........................................................................................................ E1 Receiver Electrical Characteristics .......................................................................... T1/J1 Receiver Electrical Characteristics...................................................................... E1 Transmitter Electrical Characteristics ...................................................................... T1/J1 Transmitter Electrical Characteristics.................................................................. Transmitter and Receiver Timing Characteristics ......................................................... Jitter Tolerance ............................................................................................................. Jitter Attenuator Characteristics .................................................................................... Serial Interface Timing Characteristics ......................................................................... Multiplexed Motorola Read Timing Characteristics....................................................... Multiplexed Motorola Write Timing Characteristics ....................................................... Multiplexed Intel Read Timing Characteristics .............................................................. Multiplexed Intel Write Timing Characteristics .............................................................. 45 46 47 48 48 48 49 51 51 52 52 53 54 55 56 57 58 60 62 63 64 65 66 6 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES LIST OF FIGURES Figure-1 Figure-2 Figure-3 Figure-4 Figure-5 Figure-6 Figure-7 Figure-8 Figure-9 Figure-10 Figure-11 Figure-12 Figure-13 Figure-14 Figure-15 Figure-16 Figure-17 Figure-18 Figure-19 Figure-20 Figure-21 Figure-22 Figure-23 Figure-24 Figure-25 Figure-26 Figure-27 Figure-28 Figure-29 Figure-30 Figure-31 Figure-32 Block Diagram ................................................................................................................. 2 IDT82V2081 TQFP44 Package Pin Assignment ............................................................ 8 E1 Waveform Template Diagram .................................................................................. 15 E1 Pulse Template Test Circuit ..................................................................................... 16 DSX-1 Waveform Template .......................................................................................... 16 T1 Pulse Template Test Circuit ..................................................................................... 16 Receive Path Function Block Diagram .......................................................................... 21 Transmit/Receive Line Circuit ....................................................................................... 21 Monitoring Receive Line in Another Chip ...................................................................... 22 Monitor Transmit Line in Another Chip .......................................................................... 22 Jitter Attenuator ............................................................................................................. 23 LOS Declare and Clear ................................................................................................. 24 Analog Loopback .......................................................................................................... 27 Digital Loopback ............................................................................................................ 27 Remote Loopback ......................................................................................................... 28 Auto Report Mode ......................................................................................................... 29 Manual Report Mode ..................................................................................................... 30 TCLK Operation Flowchart ............................................................................................ 31 Serial Microcontroller Interface Function Timing ........................................................... 31 Transmit System Interface Timing ................................................................................ 58 Receive System Interface Timing ................................................................................. 58 E1 Jitter Tolerance Performance .................................................................................. 59 T1/J1 Jitter Tolerance Performance .............................................................................. 59 E1 Jitter Transfer Performance ..................................................................................... 61 T1/J1 Jitter Transfer Performance ................................................................................ 61 Serial Interface Write Timing ......................................................................................... 62 Serial Interface Read Timing with SCLKE=1 ................................................................ 62 Serial Interface Read Timing with SCLKE=0 ................................................................ 62 Multiplexed Motorola Read Timing ................................................................................ 63 Multiplexed Motorola Write Timing ................................................................................ 64 Multiplexed Intel Read Timing ....................................................................................... 65 Multiplexed Intel Write Timing ....................................................................................... 66 7 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES 1 IDT82V2081 PIN CONFIGURATIONS RDY / ACK / SDO / TERM 23 ALE / AS / SCLK/ LP1 25 33 32 31 30 29 28 27 26 24 WR / R/W / SDI / LP0 AD7 / PULS3 AD6 / PULS2 AD5 / PULS1 AD4 / PULS0 AD1 / PATT1 AD0 / PATT0 AD2 / RPD AD3 / EQ IC VDDT TRING TTIP GNDT GNDA RRING RTIP VDDA REF IC 34 35 36 37 38 39 40 41 42 43 44 22 21 20 19 RD / DS / SCLKE / MONT CS / RXTXM1 INT / RXTXM0 VDDIO GNDIO MODE1 MODE0 JA1 JA0 THZ RST IDT82V2081 18 17 16 15 14 13 12 10 TDP / TD TCLK RCLK TDN RDP / RD RDN / CV GNDD VDDD MCLK Figure-2 IDT82V2081 TQFP44 Package Pin Assignment 8 RCLKE LOS 11 1 2 3 4 5 6 7 8 9 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES 2 PIN DESCRIPTION Name Type Analog output Pin No. 37 36 Description TTIP/TRING: Transmit Bipolar Tip/Ring These pins are the differential line driver outputs. They will be in high impedance state under the following conditions: * THZ pin is high; * THZ bit is set to 1; * Loss of MCLK; * Loss of TCLK (exceptions: Remote Loopback; transmit internal pattern by MCLK); * Transmit path power down; * After software reset; pin reset and power on. RTIP/RRING: Receive Bipolar Tip/Ring These signals are the differential receiver inputs. TD: Transmit Data When the device is in single rail mode, the NRZ data to be transmitted is input on this pin. Data on TD pin is sampled into the device on the active edge of TCLK and is encoded by AMI, HDB3 or B8ZS line code rules before being transmitted. In this mode, TDN should be connected to ground. TDP/TDN: Positive/Negative Transmit Data When the device is in dual rail mode, the NRZ data to be transmitted for positive/negative pulse is input on these pins. Data on TDP/TDN pin is sampled into the device on the active edge of TCLK. The line code in dual rail mode is as follows: TDP 0 0 1 1 TCLK I 1 TDN 0 1 0 1 Output Pulse Space Positive Pulse Negative Pulse Space Table-1 Pin Description TTIP TRING RTIP RRING TD/TDP TDN Analog input I 41 40 2 3 TCLK: Transmit Clock input This pin inputs 1.544 MHz for T1/J1 mode or 2.048 MHz for E1 mode transmit clock. The transmit data at TD/TDP or TDN is sampled into the device on the active edge of TCLK. If TCLK is missing1 and the TCLK missing interrupt is not masked, an interrupt will be generated. RD: Receive Data output In single rail mode, this pin outputs NRZ data. The data is decoded according to AMI, HDB3 or B8ZS line code rules. CV: Code Violation indication In single rail mode, the BPV/CV code violation will be reported by driving the CV pin to high level for a full clock cycle. B8ZS/ HDB3 line code violation can be indicated if the B8ZS/HDB3 decoder is enabled. When AMI decoder is selected, bipolar violation will be indicated. In hardware control mode, the EXZ, BPV/CV errors in received data stream are always monitored by the CV pin if single rail mode is chosen. RDP/RDN: Positive/Negative Receive Data output In dual rail mode, this pin outputs the re-timed NRZ data when CDR is enabled, or directly outputs the raw RZ slicer data if CDR is bypassed. Active edge and level select: Data on RDP/RDN or RD is clocked with either the rising or the falling edge of RCLK. The active polarity is also selectable. RD/RDP CV/RDN O 5 6 RCLK O 4 RCLK: Receive Clock output This pin outputs 1.544 MHz for T1/J1 mode or 2.048 MHz for E1 mode receive clock. Under LOS condition with AIS enabled (bit AISE=1), RCLK is derived from MCLK. In clock recovery mode, this signal provides the clock recovered from the RTIP/ RRING signal. The receive data (RD in single rail mode or RDP and RDN in dual rail mode) is clocked out of the device on the active edge of RCLK. If clock recovery is bypassed, RCLK is the exclusive OR (XOR) output of the dual rail slicer data RDP and RDN. This signal can be used in applications with external clock recovery circuitry. Notes: 1. TCLK missing: the state of TCLK continues to be high level or low level over 70 MCLK cycles. 9 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES Table-1 Pin Description (Continued) Name MCLK Type I Pin No. 9 Description MCLK: Master Clock input A built-in clock system that accepts selectable 2.048MHz reference for E1 operating mode and 1.544MHz reference for T1/J1 operating mode. This reference clock is used to generate several internal reference signals: * Timing reference for the integrated clock recovery unit. * Timing reference for the integrated digital jitter attenuator. * Timing reference for microcontroller interface. * Generation of RCLK signal during a loss of signal condition. * Reference clock to transmit All Ones, all zeros, PRBS/QRSS pattern as well as activate or deactivate Inband Loopback code if MCLK is selected as the reference clock. Note that for ATAO and AIS, MCLK is always used as the reference clock. * Reference clock during the Transmit All Ones (TAO) condition or sending PRBS/QRSS in hardware control mode. The loss of MCLK will turn TTIP/TRING into high impedance status. LOS: Loss of Signal Output This is an active high signal used to indicate the loss of received signal. When LOS pin becomes high, it indicates the loss of received signal. The LOS pin will become low automatically when valid received signal is detected again. The criteria of loss of signal are described in 3.6 LOS AND AIS DETECTION. REF: reference resister An external resistor (3K, 1%) is used to connect this pin to ground to provide a standard reference current for internal circuit. MODE[1:0]: operation mode of Control interface select The level on this pin determines which control mode is used to control the device as follows: MODE[1:0] 00 01 10 11 * * * RCLKE I 11 Control Interface mode Hardware interface Serial Microcontroller Interface Parallel -Multiplexed -Motorola Interface Parallel -Multiplexed -Intel Interface LOS O 7 REF MODE1 MODE0 I I 43 17 16 The serial microcontroller Interface consists of CS, SCLK, SCLKE, SDI, SDO and INT pins. SCLKE is used for the selection of the active edge of SCLK. The parallel multiplexed microcontroller interface consists of CS, AD[7:0], DS/RD, R/W/WR, ALE/AS, ACK/RDY and INT pins. (refer to 3.12 MICROCONTROLLER INTERFACES for details) Hardware interface consists of PULS[3:0], THZ, RCLKE, LP[1:0], PATT[1:0], JA[1:0], MONT, TERM, EQ, RPD, MODE[1:0] and RXTXM[1:0] RCLKE: the active edge of RCLK select In hardware control mode, this pin selects the active edge of RCLK * L= select the rising edge as the active edge of RCLK * H= select the falling edge as the active edge of RCLK In software control mode, this pin should be connected to GNDIO. CS: Chip Select In serial or parallel microcontroller interface mode, this is the active low enable signal. A low level on this pin enables serial or parallel microcontroller interface. RXTXM[1:0]: Receive and transmit path operation mode select In hardware control mode, these pins are used to select the single rail or dual rail operation modes as well as AMI or HDB3/ B8ZS line coding: * 00= single rail with HDB3/B8ZS coding * 01= single rail with AMI coding * 10= dual rail interface with CDR enabled * 11= slicer mode (dual rail interface with CDR disabled) CS I 21 RXTXM1 10 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES Table-1 Pin Description (Continued) Name INT Type O Pin No. 20 Description INT: Interrupt Request In software control mode, this pin outputs the general interrupt request for all interrupt sources. These interrupt sources can be masked individually via registers (INTM0, 14H) and (INTM1, 15H). The interrupt status is reported via the registers (INTS0, 19H) and (INTS1, 1AH). Output characteristics of this pin can be defined to be push-pull (active high or active low) or open-drain (active low) by setting INT_PIN[1:0] (GCF, 02H). RXTXM0 See RXTXM1 above. 25 SCLK: Shift Clock In serial microcontroller interface mode, this signal is the shift clock for the serial interface. Configuration data on SDI pin is sampled on the rising edge of SCLK. Configuration and status data on SDO pin is clocked out of the device on the falling edge of SCLK if SCLKE pin is high, or on the rising edge of SCLK if SCLKE pin is low. ALE: Address Latch Enable In parallel microcontroller interface mode with multiplexed Intel interface, the address on AD[7:0] is sampled into the device on the falling edge of ALE. AS: Address Strobe In parallel microcontroller interface mode with multiplexed Motorola interface, the address on AD[7:0] is latched into the device on the falling edge of AS. LP[1:0]: Loopback mode select When the chip is configured by hardware, this pin is used to select loopback operation modes (Inband Loopback is not provided in hardware control mode) * 00= no loopback * 01= analog loopback * 10= digital loopback * 11= remote loopback I 24 SDI: Serial Data Input In serial microcontroller interface mode, this signal is the input data to the serial interface. Configuration data at SDI pin is sampled by the device on the rising edge of SCLK. WR: Write Strobe In Intel parallel multiplexed interface mode, this pin is asserted low by the microcontroller to initiate a write cycle. The data on AD[7:0] is sampled into the device in a write operation. R/W: Read/Write Select In Motorola parallel multiplexed interface mode, this pin is low for write operation and high for read operation. LP0 See LP1 above. RXTXM0 SCLK I I ALE AS LP1 SDI WR R/W LP0 11 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES Table-1 Pin Description (Continued) Name SDO Type O Pin No. 23 Description SDO: Serial Data Output In serial microcontroller interface mode, this signal is the output data of the serial interface. Configuration or Status data at SDO pin is clocked out of the device on the falling edge of SCLK if SCLKE pin is high, or on the rising edge of SCLK if SCLKE pin is low. ACK: Acknowledge Output In Motorola parallel mode interface, the low level on this pin means: * The valid information is on the data bus during a read operation. * The write data has been accepted during a write cycle. RDY: Ready signal output In Intel parallel mode interface, the low level on this pin means a read or write operation is in progress; a high acknowledges a read or write operation has been completed. I TERM: Internal or external termination select in hardware mode This pin selects internal or external impedance matching for both receiver and transmitter. * 0 = ternary interface with external impedance matching network * 1 = ternary interface with internal impedance matching network 22 SCLKE: Serial Clock Edge Select In serial microcontroller interface mode, this signal selects the active edge of SCLK for outputting SDO. The output data is valid after some delay from the active clock edge. It can be sampled on the opposite edge of the clock. The active clock edge which clocks the data out of the device is selected as shown below: SCLKE Low High SCLK Rising edge is the active edge. Falling edge is the active edge. ACK RDY TERM SCLKE I RD RD: Read Strobe In Intel parallel multiplexed interface mode, the data is driven to AD[7:0] by the device during low level of RD in a read operation. DS: Data Strobe In Motorola parallel multiplexed interface mode, this signal is the data strobe of the parallel interface. In a write operation (R/ W = 0), the data on AD[7:0] is sampled into the device. In a read operation (R/W = 1), the data is driven to AD[7:0] by the device. MONT: Receive Monitor gain select In hardware control mode with ternary interface, this pin selects the receive monitor gain of receiver: 0= 0dB 1= 26dB I/O 33 AD7: Address/Data Bus bit7 In Intel/Motorola multiplexed interface mode, this signal is the multiplexed bi-directional address/data bus of the microcontroller interface. In serial microcontroller interface mode, this pin should be connected to ground through a 10 k resistor. PULS[3:0]: these pins are used to select the following functions in hardware control mode: * T1/J1/E1 mode * Transmit pulse template * Internal termination impedance (75/120/100/110) Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. 32 AD6: Address/Data Bus bit6 In Intel/Motorola multiplexed interface mode, this signal is the multiplexed bi-directional address/data bus of the microcontroller interface. In serial microcontroller interface mode, this pin should be connected to ground through a 10 k resistor. See above. DS MONT AD7 PULS3 I AD6 I/O PULS2 I 12 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES Table-1 Pin Description (Continued) Name AD5 Type I/O Pin No. 31 Description AD5: Address/Data Bus bit5 In Intel/Motorola multiplexed interface mode, this signal is the multiplexed bi-directional address/data bus of the microcontroller interface. In serial microcontroller interface mode, this pin should be connected to ground through a 10 k resistor. See above. 30 AD4: Address/Data Bus bit4 In Intel/Motorola multiplexed interface mode, this signal is the multiplexed bi-directional address/data bus of the microcontroller interface. In serial microcontroller interface mode, this pin should be connected to ground through a 10 k resistor. See above. 29 AD3: Address/Data Bus bit3 In Intel/Motorola multiplexed interface mode, this signal is the multiplexed bi-directional address/data bus of the microcontroller interface. In serial microcontroller interface mode, this pin should be connected to ground through a 10 k resistor. EQ: Receive Equalizer on/off control in hardware control mode * 0= short haul (10 dB) * 1= long haul (36 dB for T1/J1, 43 dB for E1) 28 AD2: Address/Data Bus bit2 In Intel/Motorola multiplexed interface mode, this signal is the multiplexed bi-directional address/data bus of the microcontroller interface. In serial microcontroller interface mode, this pin should be connected to ground through a 10 k resistor. RPD: Receiver power down control in hardware control mode * 0= normal operation * 1= receiver power down 27 AD1: Address/Data Bus bit1 In Intel/Motorola multiplexed interface mode, this signal is the multiplexed bi-directional address/data bus of the microcontroller interface. In serial microcontroller interface mode, this pin should be connected to ground through a 10 k resistor. PATT[1:0]: Transmit pattern select In hardware control mode, this pin selects the transmit pattern * 00 = normal * 01= All Ones * 10= PRBS * 11= transmitter power down 26 AD0: Address/Data Bus bit0 In Intel/Motorola multiplexed interface mode, this signal is the multiplexed bi-directional address/data bus of the microcontroller interface. In serial microcontroller interface mode, this pin should be connected to ground through a 10 k resistor. See above. 15 JA[1:0]: Jitter attenuation position, bandwidth and the depth of FIFO select (only used for hardware control mode) * 00 = JA is disabled * 01 = JA in receiver, broad bandwidth, FIFO=64 bits * 10 = JA in receiver, narrow bandwidth, FIFO=128 bits * 11 = JA in transmitter, narrow bandwidth, FIFO=128 bits In software control mode, this pin should be connected to ground. See above. RST: Hardware reset The chip is forced to reset state if a low signal is input on this pin for more than 100ns. PULS1 AD4 I I/O PULS0 AD3 I I/O EQ I AD2 I/O RPD I AD1 I/O PATT1 I AD0 I/O PATT0 JA1 I I JA0 RST I I 14 12 13 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES Table-1 Pin Description (Continued) Name THZ Type I Pin No. 13 Description THZ: Output Driver tri-state Enable This signal enables or disables transmitter driver. A low level on this pin enables the driver while a high level on this pin places driver in high impedance state. Note that the functionality of the internal circuits is not affected by this signal. Power Supplies and Grounds VDDIO GNDIO VDDT GNDT VDDA GNDA VDDD GNDD IC IC 19 18 35 38 42 39 8 10 34 44 3.3 V I/O power supply I/O ground 3.3 V power supply for transmitter driver Analog ground for transmitter driver 3.3 V analog core power supply Analog core ground Digital core power supply Digital core ground Others IC: Internal connection Internal Use. This pin should be left open when in normal operation. IC: Internal connection Internal Use. This pin should be connected to ground when in normal operation. 14 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES 3 3.1 FUNCTIONAL DESCRIPTION CONTROL MODE SELECTION 3.3.2 ENCODER The IDT82V2081 can be configured by software or by hardware. The software control mode supports Serial Control Interface, Motorola Multiplexed Control Interface and Intel Multiplexed Control Interface. The Control mode is selected by MODE1 and MODE0 pins as follows: Control Interface mode 00 01 10 11 Hardware interface Serial Microcontroller Interface. Parallel -Multiplexed -Motorola Interface Parallel -Multiplexed -Intel Interface In Single Rail mode, when T1/J1 mode is selected, the Encoder can be selected to be a B8ZS encoder or an AMI encoder by setting T_MD[0] bit (TCF0, 05H). In Single Rail mode, when E1 mode is selected, the Encoder can be configured to be a HDB3 encoder or an AMI encoder by setting T_MD[0] bit (TCF0, 05H). In both T1/J1 mode and E1 mode, when Dual Rail mode is selected (bit T_MD[1] is `1'), the Encoder is by-passed. In Dual Rail mode, a logic `1' on the TDP pin and a logic `0' on the TDN pin results in a negative pulse on the TTIP/TRING; a logic `0' on TDP pin and a logic `1' on TDN pin results in a positive pulse on the TTIP/TRING. If both TDP and TDN are high or low, the TTIP/TRING outputs a space (Refer to TD/TDP, TDN Pin Description). In hardware control mode, the operation mode of receive and transmit path can be selected by setting RXTXM1 and RXTXM0 pins. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. 3.3.3 PULSE SHAPER The IDT82V2081 provides three ways of manipulating the pulse shape before sending it. The first is to use preset pulse templates for short haul application, the second is to use LBO (Line Build Out) for long haul application and the other way is to use user-programmable arbitrary waveform template. In software control mode, the pulse shape can be selected by setting the related registers. In hardware control mode, the pulse shape can be selected by setting PULS[3:0] pins. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. 3.3.3.1 Preset Pulse Templates For E1 applications, the pulse shape is shown in Figure-3 according to the G.703 and the measuring diagram is shown in Figure-4. In internal impedance matching mode, if the cable impedance is 75 , the PULS[3:0] bits (TCF1, 06H) should be set to `0000'; if the cable impedance is 120 , the PULS[3:0] bits (TCF1, 06H) should be set to `0001'. In external impedance matching mode, for both E1/75 and E1/120 cable impedance, PULS[3:0] should be set to `0001'. 1 .2 0 * * * The serial microcontroller Interface consists of CS, SCLK, SCLKE, SDI, SDO and INT pins. SCLKE is used for the selection of active edge of SCLK. The parallel Multiplexed microcontroller Interface consists of CS, AD[7:0], DS/RD, R/W/WR, ALE/AS, ACK/RDY and INT pins. Hardware interface consists of PULS[3:0], THZ, RCLKE, LP[1:0], PATT[1:0], JA[1:0], MONT, TERM, EQ, RPD, MODE[1:0] and RXTXM[1:0]. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details about hardware control. 3.2 T1/E1/J1 MODE SELECTION When the chip is configured by software, T1/E1/J1 mode is selected by the T1E1 bit (GCF, 02H). In E1 application, the T1E1 bit (GCF, 02H) should be set to `0'. In T1/J1 application, the T1E1 bit should be set to `1'. When the chip is configured by hardware, T1/E1/J1 mode is selected by PULS[3:0] pins. These pins also determine transmit pulse template and internal termination impedance. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. 3.3 TRANSMIT PATH The transmit path of IDT82V2081 consists of an Encoder, an optional Jitter Attenuator, a Waveform Shaper, a set of LBOs, a Line Driver and a Programmable Transmit Termination. 3.3.1 TRANSMIT PATH SYSTEM INTERFACE The transmit path system interface consists of TCLK pin, TD/TDP pin and TDN pin. In E1 mode, TCLK is a 2.048 MHz clock. In T1/J1 mode, TCLK is a 1.544 MHz clock. If TCLK is missing for more than 70 MCLK cycles, an interrupt will be generated if it is not masked. Transmit data is sampled on the TD/TDP and TDN pins by the active edge of TCLK. The active edge of TCLK can be selected by the TCLK_SEL bit (TCF0, 05H). And the active level of the data on TD/TDP and TDN can be selected by the TD_INV bit (TCF0, 05H). In hardware control mode, the falling edge of TCLK and the active high of transmit data are always used. The transmit data from the system side can be provided in two different ways: Single Rail and Dual Rail. In Single Rail mode, only TD pin is used for transmitting data and the T_MD[1] bit (TCF0, 05H) should be set to `0'. In Dual Rail Mode, both TDP pin and TDN pin are used for transmitting data, the T_MD[1] bit (TCF0, 05H) should be set to `1'. 1 .0 0 0 .8 0 Normalized Amplitude 0 .6 0 0 .4 0 0 .2 0 0 .0 0 -0 .2 0 - 0 .6 -0 .4 -0 .2 0 T im e in U n it In te rv a ls 0 .2 0 .4 0 .6 Figure-3 E1 Waveform Template Diagram 15 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES 3.3.3.3 User-Programmable Arbitrary Waveform TTIP IDT82V2081 TRING Note: 1. For RLOAD = 75 (nom), Vout (Peak)=2.37V (nom) 2. For RLOAD =120 (nom), Vout (Peak)=3.00V (nom) RLOAD VOUT When the PULS[3:0] bits are set to `11xx', user-programmable arbitrary waveform generator mode can be used. This allows the transmitter performance to be tuned for a wide variety of line condition or special application. Each pulse shape can extend up to 4 UIs (Unit Interval), addressed by UI[1:0] bits (TCF3, 08H) and each UI is divided into 16 sub-phases, addressed by the SAMP[3:0] bits (TCF3, 08H). The pulse amplitude of each phase is represented by a binary byte, within the range from +63 to -63, stored in WDAT[6:0] bits (TCF4, 09H) in signed magnitude form. The most positive number +63 (D) represents the positive maximum amplitude of the transmit pulse while the most negative number -63 (D) represents the maximum negative amplitude of the transmit pulse. Therefore, up to 64 bytes are used. There are twelve standard templates which are stored in an on-chip ROM. User can select one of them as reference and make some changes to get the desired waveform. User can change the wave shape and the amplitude to get the desired pulse shape. In order to do this, firstly, users can choose a set of waveform value from the following twelve tables, which is the most similar to the desired pulse shape. Table-2, Table-3, Table-4, Table-5, Table-6, Table-7, Table-8, Table-9, Table-10, Table-11, Table-12 and Table-13 list the sample data and scaling data of each of the twelve templates. Then modify the corresponding sample data to get the desired transmit pulse shape. Secondly, through the value of SCAL[5:0] bits increased or decreased by 1, the pulse amplitude can be scaled up or down at the percentage ratio against the standard pulse amplitude if needed. For different pulse shapes, the value of SCAL[5:0] bits and the scaling percentage ratio are different. The following twelve tables list these values. Figure-4 E1 Pulse Template Test Circuit For T1 applications, the pulse shape is shown in Figure-5 according to the T1.102 and the measuring diagram is shown in Figure-6. This also meets the requirement of G.703, 2001. The cable length is divided into five grades, and there are five pulse templates used for each of the cable length. The pulse template is selected by PULS[3:0] bits (TCF1, 06H). 1.2 1 0.8 Normalized Amplitude 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 0 250 500 Time (ns) 750 1000 1250 Figure-5 DSX-1 Waveform Template TTIP Cable IDT82V2081 TRING Note: RLOAD = 100 5% RLOAD VOUT Do the followings step by step, the desired waveform can be programmed, based on the selected waveform template: (1).Select the UI by UI[1:0] bits (TCF3, 08H) (2).Specify the sample address in the selected UI by SAMP [3:0] bits (TCF3, 08H) (3).Write sample data to WDAT[6:0] bits (TCF4, 09H). It contains the data to be stored in the RAM, addressed by the selected UI and the corresponding sample address. (4).Set the RW bit (TCF3, 08H) to `0' to implement writing data to RAM, or to `1' to implement read data from RAM (5).Implement the Read from RAM/Write to RAM by setting the DONE bit (TCF3, 08H) Repeat the above steps until all the sample data are written to or read from the internal RAM. (6).Write the scaling data to SCAL[5:0] bits (TCF2, 07H) to scale the amplitude of the waveform based on the selected standard pulse amplitude When more than one UI is used to compose the pulse template, the overlap of two consecutive pulses could make the pulse amplitude overflow (exceed the maximum limitation) if the pulse amplitude is not set properly. This overflow is captured by DAC_OV_IS bit (INTS1, 1AH), and, if enabled by the DAC_OV_IM bit (INTM1, 15H), an interrupt will be generated. The following tables give all the sample data based on the preset pulse templates and LBOs in detail for reference. For preset pulse templates and LBOs, scaling up/down against the pulse amplitude is not supported. Figure-6 T1 Pulse Template Test Circuit For J1 applications, the PULS[3:0] (TCF1, 06H) should be set to `0111'. Table-14 lists these values. 3.3.3.2 LBO (Line Build Out) To prevent the cross-talk at the far end, the output of TTIP/TRING could be attenuated before transmission for long haul applications. The FCC Part 68 Regulations specifies four grades of attenuation with a step of 7.5 dB. Three LBOs are used to implement the pulse attenuation. The PULS[3:0] bits (TCF1, 06H) are used to select the attenuation grade. Both Table-14 and Table-15 list these values. 16 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES 1.Table-2 Transmit Waveform Value For E1 75 2.Table-3 Transmit Waveform Value For E1 120 3. Table-4 Transmit Waveform Value For T1 0~133 ft 4.Table-5 Transmit Waveform Value For T1 133~266 ft 5.Table-6 Transmit Waveform Value For T1 266~399 ft 6.Table-7 Transmit Waveform Value For T1 399~533 ft 7.Table-8 Transmit Waveform Value For T1 533~655 ft 8.Table-9 Transmit Waveform Value For J1 0~655 ft 9.Table-10 Transmit Waveform Value For DS1 0 dB LBO 10.Table-11 Transmit Waveform Value For DS1 -7.5 dB LBO 11.Table-12 Transmit Waveform Value For DS1 -15.0 dB LBO 12.Table-13 Transmit Waveform Value For DS1 -22.5 dB LBO Table-3 Transmit Waveform Value For E1 120 Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 UI 1 0000000 0000000 0000000 0001111 0111100 0111100 0111100 0111100 0111100 0111100 0111100 0111100 0000000 0000000 0000000 0000000 UI 2 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 3 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 4 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 Table-2 Transmit Waveform Value For E1 75 Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 UI 1 0000000 0000000 0000000 0001100 0110000 0110000 0110000 0110000 0110000 0110000 0110000 0110000 0000000 0000000 0000000 0000000 UI 2 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 3 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 4 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 SCAL[5:0] = 100001 (default), One step change of this value of SCAL[5:0] results in 3% scaling up/down against the pulse amplitude. Table-4 Transmit Waveform Value For T1 0~133 ft Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 UI 1 0011010 0100111 0100111 0100110 0100110 0100101 0100101 0100101 0100101 1001010 1001010 1001010 1000100 1000100 1000100 1000010 1101101 UI 2 1000010 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 3 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 4 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 SCAL[5:0] = 100001 (default), One step change of this value of SCAL[5:0] results in 3% scaling up/down against the pulse amplitude. SCAL[5:0] = (default), One step change of this value of SCAL[5:0] results in 2% scaling up/down against the pulse amplitude. 1. In T1 mode, when arbitrary pulse for short haul application is configured, users should write `110110' to SCAL[5:0] bits if no scaling is required. 17 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES Table-5 Transmit Waveform Value For T1 133~266 ft Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 UI 1 0011110 0101100 0101100 0101001 0101000 0101000 0100111 0100111 0100111 1001101 1001101 1001101 1000101 1000101 1000101 1000010 UI 2 1000010 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 See Table-4 UI 3 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 4 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 Table-7 Transmit Waveform Value For T1 399~533 ft Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 UI 1 0101010 0110100 0110100 0110100 0101110 0101101 0101100 0101011 0101011 1010110 1010110 1010110 1000111 1000111 1000111 1000011 UI 2 1000011 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 See Table-4 UI 3 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 4 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 Table-6 Transmit Waveform Value For T1 266~399 ft Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 UI 1 0100100 0110001 0110001 0101110 0101011 0101010 0101010 0101001 0101001 1010010 1010010 1010010 1000111 1000111 1000111 1000010 UI 2 1000010 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 See Table-4 UI 3 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 4 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 Table-8 Transmit Waveform Value For T1 533~655 ft Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 UI 1 0101101 0111000 0111000 0111000 0110001 0101110 0101101 0101100 0101100 1011010 1011010 1011010 1001010 1001000 1001000 1000100 UI 2 1000100 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 See Table-4 UI 3 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 4 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 18 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES Table-9 Transmit Waveform Value For J1 0~655 ft Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 UI 1 0011010 0100111 0100111 0100110 0100110 0100101 0100101 0100101 0100101 1001010 1001010 1001010 1000100 1000100 1000100 1000010 UI 2 1000010 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 3 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 4 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 Table-11 Transmit Waveform Value For DS1 -7.5 dB LBO Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 UI 1 0000000 0000010 0001001 0010011 0011101 0100101 0101011 0110001 0110110 0111010 0111001 0110000 0101000 0100000 0011010 0010111 UI 2 0010100 0010010 0010000 0001110 0001100 0001011 0001010 0001001 0001000 0000111 0000110 0000101 0000100 0000100 0000011 0000011 UI 3 0000010 0000010 0000010 0000010 0000010 0000001 0000001 0000001 0000001 0000001 0000001 0000001 0000000 0000000 0000000 0000000 UI 4 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 SCAL[5:0] = 110110 (default), One step change of this value of SCAL[5:0] results in 2% scaling up/down against the pulse amplitude. SCAL[5:0] = 010001 (default), One step change of this value of SCAL[5:0] results in 6.25% scaling up/down against the pulse amplitude. Table-10 Transmit Waveform Value For DS1 0 dB LBO Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 UI 1 0011010 0100111 0100111 0100110 0100110 0100101 0100101 0100101 0100101 1001010 1001010 1001010 1000100 1000100 1000100 1000010 UI 2 1000010 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 3 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 UI 4 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 0000000 Table-12 Transmit Waveform Value For DS1 -15.0 dB LBO Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 UI 1 0000000 0000000 0000000 0000001 0000100 0001000 0001110 0010100 0011011 0100010 0101010 0110000 0110101 0110111 0111000 0110111 UI 2 0110101 0110011 0110000 0101101 0101010 0100111 0100100 0100001 0011110 0011100 0011010 0010111 0010101 0010100 0010010 0010000 UI 3 0001111 0001101 0001100 0001011 0001010 0001001 0001000 0000111 0000110 0000110 0000101 0000101 0000100 0000100 0000011 0000011 UI 4 0000011 0000010 0000010 0000010 0000010 0000001 0000001 0000001 0000001 0000001 0000001 0000001 0000001 0000000 0000000 0000000 SCAL[5:0] = 110110 (default), One step change of this Value results in 2% scaling up/down against the pulse amplitude. SCAL[5:0] = 001000 (default), One step change of the value of SCAL[5:0] results in 12.5% scaling up/down against the pulse amplitude. 19 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES 3.3.4 TRANSMIT PATH LINE INTERFACE Table-13 Transmit Waveform Value For DS1 -22.5 dB LBO Sample 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 UI 1 0000001 0000011 0000101 0001000 0001100 0010001 0010110 0011011 0100001 0100110 0101010 0101110 0110001 0110011 0110100 0110100 UI 2 0110101 0110101 0110100 0110011 0110010 0110000 0101110 0101101 0101011 0101001 0100111 0100100 0100010 0100000 0011110 0011100 UI 3 0011011 0011001 0010111 0010101 0010100 0010010 0010001 0010000 0001110 0001101 0001100 0001011 0001010 0001001 0001000 0001000 UI 4 0000111 0000110 0000110 0000101 0000101 0000101 0000100 0000100 0000100 0000100 0000011 0000011 0000011 0000011 0000011 0000010 The transmit line interface consists of TTIP pin and TRING pin. The impedance matching can be realized by the internal impedance matching circuit or the external impedance matching circuit. If T_TERM[2] is set to `0', the internal impedance matching circuit will be selected. In this case, the T_TERM[1:0] bits (TERM, 03H) can be set to choose 75 , 100 , 110 or 120 internal impedance of TTIP/TRING. If T_TERM[2] is set to `1', the internal impedance matching circuit will be disabled. In this case, the external impedance matching circuit will be used to realize the impedance matching. For T1/J1 mode, the external impedance matching circuit for the transmitter is not supported. Figure-8 shows the appropriate external components to connect with the cable. Table-14 is the list of the recommended impedance matching for transmitter. SCAL[5:0] = 000100 (default), One step change of this value of SCAL[5:0] results in 25% scaling up/down against the pulse amplitude. Table-14 Impedance Matching for Transmitter Cable Configuration E1/75 E1/120 T1/0~133 ft T1/133~266 ft T1/266~399 ft T1/399~533 ft T1/533~655 ft J1/0~655 ft 0 dB LBO -7.5 dB LBO -15.0 dB LBO -22.5 dB LBO Note: The precision of the resistors should be better than 1% 011 010 000 001 010 Internal Termination T_TERM[2:0] PULS[3:0] 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 RT 0 T_TERM[2:0] 1XX External Termination PULS[3:0] 0001 0001 RT 9.4 In hardware control mode, TERM pin can be used to select impedance matching for both receiver and transmitter. If TERM pin is low, external impedance network will be used for impedance matching. If TERM pin is high, internal impedance will be used for impedance matching and PULS[3:0] pins will be set to select the specific internal impedance. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. The TTIP/TRING pins can also be turned into high impedance by setting the THZ bit (TCF1, 06H) to `1'. In this state, the internal transmit circuits are still active. In hardware control mode, TTIP/TRING can be turned into high impedance by pulling THZ pin to high. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. Besides, in the following cases, both TTIP/TRING pins will also become high impedance: * Loss of MCLK; * Loss of TCLK (exceptions: Remote Loopback; Transmit internal pattern by MCLK); * Transmit path power down; * After software reset; pin reset and power on. 20 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES 3.3.5 TRANSMIT PATH POWER DOWN 3.4 RECEIVE PATH The transmit path can be powered down by setting the T_OFF bit (TCF0, 05H) to `1'. In this case, the TTIP/TRING pins are turned into high impedance. In hardware control mode, the transmit path can be powered down by pulling both PATT1 and PATT0 pins to high. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. The receive path consists of Receive Internal Termination, Monitor Gain, Amplitude/Wave Shape Detector, Digital Tuning Controller, Adaptive Equalizer, Data Slicer, CDR (Clock & Data Recovery), Optional Jitter Attenuator, Decoder and LOS/AIS Detector. Refer to Figure-7. LOS/AIS Detector LOS RTIP RRING Receive Internal termination Monitor Gain Adaptive Equalizer Data Slicer Clock and Data Recovery Jitter Attenuator RCLK Decoder RDP RDN Figure-7 Receive Path Function Block Diagram 3.4.1 RECEIVE INTERNAL TERMINATION The impedance matching can be realized by the internal impedance matching circuit or the external impedance matching circuit. If R_TERM[2] is set to `0', the internal impedance matching circuit will be selected. In this case, the R_TERM[1:0] bits (TERM, 03H) can be set to choose 75 , 100 , 110 or 120 internal impedance of RTIP/RRING. If R_TERM[2] is set to `1', the internal impedance matching circuit will be disabled. In this case, the external impedance matching circuit will be used to realize the impedance matching. Figure-8 shows the appropriate external components to connect with the cable. Table-15 is the list of the recommended impedance matching for receiver. Table-15 Impedance Matching for Receiver Cable Configuration E1/75 E1/120 T1 J1 Internal Termination R_TERM[2:0] 000 001 010 011 RR 120 1XX External Termination R_TERM[2:0] RR 75 120 100 110 A RX Line * 1:1 * RR VDDA D8 * VDDA D7 D6 D5 * * RTIP VDDA 0.1F 3.3 V 68F 1 * 3.3 V 0.1F 68F 1 * IDT82V2081 B 2:1 ** TX Line Cp * RT * * VDDT D4 D3 VDDT D2 RRING * * TTIP GNDA VDDT RT D1 * * TRING GNDT Note: 1. Common decoupling capacitor 2. Cp 0-560 (pF) 3. D1 - D8, Motorola - MBR0540T1; International Rectifier - 11DQ04 or 10BQ060 Figure-8 Transmit/Receive Line Circuit 21 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES In hardware control mode, TERM, PULS[3:0] pins can be used to select impedance matching for both receiver and transmitter. If TERM pin is low, external impedance network will be used for impedance matching. If TERM pin is high, internal impedance will be used for impedance matching and PULS[3:0] pins can be set to select the specific internal impedance. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. 3.4.2 LINE MONITOR In both T1/J1 and E1 short haul applications, the non-intrusive monitoring on channels located in other chips can be performed by tapping the monitored channel through a high impedance bridging circuit. Refer to Figure9 and Figure-11. After a high resistance bridging circuit, the signal arriving at the RTIP/ RRING is dramatically attenuated. To compensate this attenuation, the Monitor Gain can be used to boost the signal by 22 dB, 26 dB and 32 dB, selected by MG[1:0] bits (RCF2, 0CH). For normal operation, the Monitor Gain should be set to 0 dB. In hardware control mode, MONT pin can be used to set the Monitor Gain. When MONT pin is low, the Monitor Gain is 0 dB. When MONT pin is high, the Monitor Gain is 26 dB. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. DSX cross connect point RTIP When the adaptive equalizer is out of range, EQ_S bit (STAT0, 17H) will be set to `1' to indicate the status of equalizer. If EQ_IES bit (INTES, 16H) is set to `1', any changes of EQ_S bit will generate an interrupt and EQ_IS bit (INTS0, 19H) will be set to `1' if it is not masked. If EQ_IES is set to `0', only the `0' to `1' transition of the EQ_S bit will generate an interrupt and EQ_IS bit will be set to `1' if it is not masked. The EQ_IS bit will be reset after being read. The Amplitude/wave shape detector keeps on measuring the amplitude/wave shape of the incoming signals during an observation period. This observation period can be 32, 64, 128 or 256 symbol periods, as selected by UPDW[1:0] bits (RCF2, 0CH). A shorter observation period allows quicker responses to pulse amplitude variation while a longer observation period can minimize the possible overshoots. The default observation period is 128 symbol periods. Based on the observed peak value for a period, the equalizer will be adjusted to achieve a normalized signal. LATT[4:0] bits (STAT1, 18H) indicate the signal attenuation introduced by the cable in approximately 2 dB per step. 3.4.4 RECEIVE SENSITIVITY For short haul application, the Receive Sensitivity for both E1 and T1/ J1 is -10 dB. For long haul application, the receive sensitivity is -43 dB for E1 and -36 dB for T1/J1. When the chip is configured by hardware, the short haul or long haul operating mode can be selected by setting EQ pin. For short haul mode, the Receive Sensitivity for both E1 and T1/J1 is -10 dB. For long haul mode, the receive sensitivity is -43 dB for E1 and -36 dB for T1/J1. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. 3.4.5 DATA SLICER The Data Slicer is used to generate a standard amplitude mark or a space according to the amplitude of the input signals. The threshold can be 40%, 50%, 60% or 70%, as selected by the SLICE[1:0] bits (RCF2, 0CH). The output of the Data Slicer is forwarded to the CDR (Clock & Data Recovery) unit or to the RDP/RDN pins directly if the CDR is disabled. 3.4.6 CDR (Clock & Data Recovery) The CDR is used to recover the clock and data from the received signal. The recovered clock tracks the jitter in the data output from the Data Slicer and keeps the phase relationship between data and clock during the absence of the incoming pulse. The CDR can also be by-passed in the Dual Rail mode. When CDR is by-passed, the data from the Data Slicer is output to the RDP/RDN pins directly. 3.4.7 DECODER In T1/J1 applications, the R_MD[1:0] bits (RCF0, 0AH) is used to select the AMI decoder or B8ZS decoder. In E1 applications, the R_MD[1:0] bits (RCF0, 0AH) are used to select the AMI decoder or HDB3 decoder. When the chip is configured by hardware, the operation mode of receive and transmit path can be selected by setting RXTXM1 and RXTXM0 pins. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. 3.4.8 RECEIVE PATH SYSTEM INTERFACE The receive path system interface consists of RCLK pin, RD/RDP pin and RDN pin. In E1 mode, the RCLK outputs a recovered 2.048 MHz clock. In T1/J1 mode, the RCLK outputs a recovered 1.544 MHz clock. The 22 monitor gain=0dB RRING R normal receive mode RTIP monitor gain =22/26/32dB RRING monitor mode Figure-9 Monitoring Receive Line in Another Chip DSX cross connect point TTIP TRING R normal transmit mode RTIP monitor gain monitor gain =22/26/32dB RRING monitor mode Figure-10 Monitor Transmit Line in Another Chip 3.4.3 ADAPTIVE EQUALIZER The adaptive equalizer can remove most of the signal distortion due to intersymbol interference caused by cable attenuation. It can be enabled or disabled by setting EQ_ON bit to `1' or `0' (RCF1, 0BH). SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES received data is updated on the RD/RDP and RDN pins on the active edge of RCLK. The active edge of RCLK can be selected by the RCLK_SEL bit (RCF0, 0AH). And the active level of the data on RD/RDP and RDN can be selected by the RD_INV bit (RCF0, 0AH). In hardware control mode, only the active edge of RCLK can be selected. If RCLKE is set to high, the falling edge will be chosen as the active edge of RCLK. If RCLKE is set to low, the rising edge will be chosen as the active edge of RCLK. The active level of the data on RD/RDP and RDN is the same as that in software control mode. The received data can be output to the system side in two different ways: Single Rail or Dual Rail, as selected by R_MD bit [1] (RCF0, 0AH). In Single Rail mode, only RD pin is used to output data and the RDN/CV pin is used to report the received errors. In Dual Rail Mode, both RDP pin and RDN pin are used for outputting data. In the receive Dual Rail mode, the CDR unit can be by-passed by setting R_MD[1:0] to `11' (binary). In this situation, the output data from the Data Slicer will be output to the RDP/RDN pins directly, and the RCLK outputs the exclusive OR (XOR) of the RDP and RDN. This is called receiver slicer mode. In this case, the transmit path is still operating in Dual Rail mode. 3.4.9 RECEIVE PATH POWER DOWN The receive path can be powered down by setting R_OFF bit (RCF0, 0AH) to `1'. In this case, the RCLK, RD/RDP, RDN and LOS will be logic low. In hardware control mode, receiver power down can be selected by pulling RPD pin to high. Refer to 5 HARDWARE CONTROL PIN SUMMARY for more details. Jittered Data FIFO 32/64/128 W R RD/RDP De-jittered Data RDN Jittered Clock DPLL De-jittered Clock RCLK MCLK Figure-11 Jitter Attenuator In E1 applications, the Corner Frequency of the DPLL can be 0.9 Hz or 6.8 Hz, as selected by the JABW bit (JACF, 04H). In T1/J1 applications, the Corner Frequency of the DPLL can be 1.25 Hz or 5.00 Hz, as selected by the JABW bit (JACF, 04H). The lower the Corner Frequency is, the longer time is needed to achieve synchronization. When the incoming data moves faster than the outgoing data, the FIFO will overflow. This overflow is captured by the JAOV_IS bit (INTS1, 1AH). If the incoming data moves slower than the outgoing data, the FIFO will underflow. This underflow is captured by the JAUD_IS bit (INTS1, 1AH). For some applications that are sensitive to data corruption, the JA limit mode can be enabled by setting JA_LIMIT bit (JACF, 04H) to `1'. In the JA limit mode, the speed of the outgoing data will be adjusted automatically when the FIFO is close to its full or emptiness. The criteria of starting speed adjustment are shown in Table-16. The JA limit mode can reduce the possibility of FIFO overflow and underflow, but the quality of jitter attenuation is deteriorated. 3.5 JITTER ATTENUATOR There is one Jitter Attenuator in the IDT82V2081. The Jitter Attenuator can be deployed in the transmit path or the receive path, and can also be disabled. This is selected by the JACF[1:0] bits (JACF, 04H). In hardware control mode, Jitter Attenuator position, bandwidth and the depth of FIFO can be selected by JA[1:0] pins. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. 3.5.1 JITTER ATTENUATION FUNCTION DESCRIPTION The Jitter Attenuator is composed of a FIFO and a DPLL, as shown in Figure-11. The FIFO is used as a pool to buffer the jittered input data, then the data is clocked out of the FIFO by a de-jittered clock. The depth of the FIFO can be 32 bits, 64 bits or 128 bits, as selected by the JADP[1:0] bits (JACF, 04H). In hardware control mode, the depth of FIFO can be selected by JA[1:0] pins. Refer to 5 HARDWARE CONTROL PIN SUMMARY for details. Consequently, the constant delay of the Jitter Attenuator will be 16 bits, 32 bits or 64 bits. Deeper FIFO can tolerate larger jitter, but at the cost of increasing data latency time. Table-16 Criteria of Starting Speed Adjustment FIFO Depth 32 Bits 64 Bits 128 Bits Criteria for Adjusting Data Outgoing Speed 2 bits close to its full or emptiness 3 bits close to its full or emptiness 4 bits close to its full or emptiness 3.5.2 JITTER ATTENUATOR PERFORMANCE The performance of the Jitter Attenuator in the IDT82V2081 meets the ITU-T I.431, G.703, G.736-739, G.823, G.824, ETSI 300011, ETSI TBR12/ 13, AT&T TR62411 specifications. Details of the Jitter Attenuator performance is shown in Table-63 Jitter Tolerance and Table-64 Jitter Attenuator Characteristics. 3.6 3.6.1 LOS AND AIS DETECTION LOS DETECTION The Loss of Signal Detector monitors the amplitude of the incoming signal level and pulse density of the received signal on RTIP and RRING. 23 SINGLE CHANNEL T1/E1/J1 LONG HAUL/SHORT HAUL LINE INTERFACE UNIT INDUSTRIAL TEMPERATURE RANGES * LOS declare (LOS=1) A LOS is detected when the incoming signal has "no transitions", i.e., when the signal level is less than Q dB below nominal for N consecutive pulse intervals. Here N is defined by LAC bit (MAINT0, 0DH). LOS will be declared by pulling LOS pin to high (LOS=1) and LOS interrupt will be generated if it is not masked. * LOS clear (LOS=0) The LOS is cleared when the incoming signal has "transitions", i.e., when the signal level is greater than P dB below nominal and has an average pulse density of at least 12.5% for M consecutive pulse intervals, starting with the receipt of a pulse. Here M is defined by LAC bit (MAINT0, 0DH). LOS status is cleared by pulling LOS pin to low. * LOS detect level threshold In short haul mode, the amplitude threshold Q is fixed on 800 mVpp, while P=Q+200 mVpp (200 mVpp is the LOS level detect hysteresis). In long haul mode, the value of Q can be selected by LOS[4:0] bit (RCF1, 0BH), while P=Q+4 dB (4 dB is the LOS level detect hysteresis). The LOS[4:0] default value is 10101 (-46 dB). When the chip is configured by hardware, the LOS detect level is fixed if the IDT82V2081 operates in long haul mode. It is -46dB (E1) and -38dB (T1/J1). * Criteria for declare and clear of a LOS detect The detection supports the ANSI T1.231 and I.431 for T1/J1 mode and G.775 and ETSI 300233/I.431 for E1 mode. The criteria can be selected by LAC bit (MAINT0, 0DH) and T1E1 bit (GCF, 02H). Table-17 and Table-18 summarize LOS declare and clear criteria for both short haul and long haul application. * All Ones output during LOS On the system side, the RDP/RDN will reflect the input pulse "transition" at the RTIP/RRING side and output recovered clock (but the quality of the output clock can not be guaranteed when the input level is lower than the maximum receive sensitivity) when AISE bit (MAINT0, 0DH) is 0; or output All Ones as AIS when AISE bit (MAINT0, 0DH) is 1. In this case, RCLK output is replaced by MCLK. On the line side, the TTIP/TRING will output All Ones as AIS when ATAO bit (MAINT0, 0DH) is 1. The All Ones pattern uses MCLK as the reference clock. LOS indicator is always active for all kinds of loopback modes. LOS=1 signal level>P density=OK (observing windows= M) signal level LOS=0 |
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