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CT1815 10MHz Low Level Serial Interface for MIL-STD-1397 Type D
Features
* * * * * * * * * Internally set threshold Matched to 50 ohm system impedance power on and off Operates with 5 volt supplies Power management Accepts synchronous input data Unique Manchester decoder requires no clock Generates one clock per received bit May be used for serial decoding of indefinite word lengths Other Wire and Fiber Optic types available
CIRCUIT TECHNOLOGY
www.aeroflex.com
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ISO 9001
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General Description
The CT1815 is a single hybrid micro-circuit which incorporates a serial encoder, transceiver, and Manchester decoder in one package. The encoder accepts serial NRZ data in conjunction with two synchronous clocks. This data stream is then Manchester encoded and maybe transformer coupled thru an external transformer to a 75 ohm tri-axial cable for transmission through up to 1000 feet of cable. The CT1815 receiver section accepts bipolar Manchester encoded signals and passes level detected signals to the serial decoder. The serial decoder reconstructs an NRZ data stream with derived clock. This allows the data to be processed by our CT2500 monolithic protocol chip for MIL-STD-1397 serial interfaces. All the input and output signals of the CT1815 are completely compatible with the CT2500. The CT1815 has a power management function. A transmitter standby mode is available to reduce the overall power consumption of the CT1815. Aeroflex Circuit Technology is an 80,000ft2 MIL-PRF-38534 certified facility in Plainview, N.Y.
Serial NRZ Data 10 MHz Shift Clock 20 MHz Gated Clock Envelope Master Reset Encoder Enable Power Management Power Management Decoded Data Envelope Manchester Decoder and Clock Regeneration ClockR Decoded DataR Data Reconstruction Serial Manchester Encoder
XFMR SEC/DATA Input
XFMR SEC Primary Data Output 78 Primary Data Output XFMR SEC
ACT15-1031 External to Hybrid
1CT:1 +5V
XFMR SEC/DATA Input
Rx Strobe
Figure 1 - Block Diagram eroflex Circuit Technology - Data Bus Modules For The Future (c) SCDCT1815 REV A 6/12/98
Transmission
The CT1815 accepts synchronous NRZ Data in conjunction with two clocks signals. The NRZ data stream is then converted to Manchester code which is transformer coupled to a 75 ohm Tri-axial cable for transmission up to 1000 ft. The transmitter may be placed into standby condition. This reduces power consumption by approximately 600mW. Power management is made available via two standard TTL input pins. The Receiver is always active and is not affected by the power management circuitry. The transceiver is matched for 75 ohm operation over a wide band of frequencies. This condition is maintained with power on and off.
synchronously with a recovered clock. The receiver is designed to meet the MIL-STD-1397 Type D requirements.
Electrical Requirements
The specification detailed herein encompasses a hybrid Transceiver/Encoder-Decoder designed to meet the requirements of the MIL-STD-1397 Type D. The transceiver is transformer coupled to the specified triaxial cable and is screened to the individual test methods of MIL-STD-883 See Figure 1 for Block Diagram. Inputs and Outputs are all Synchronous NRZ DATA STREAMS
Transformer Isolation
The CT1815 is connected with pin 3 and pin 32 to the ACT15-1031 transformer secondary winding. The center tap of the secondary winding is connected to +5 volts. For matching 75 load operation, a 78 resistor must be placed across the primary winding of the transformer.
Reception
The CT1815 receiver section accepts a bipolar signal which is level detected and passed to the serial decoder. The decoder section reconstructs the data and strips the clock from the serial stream. An NRZ decoded data stream is then produced
Encoder Timing / Transmitter Specification
Symbol Parameter / Condition Encode Timing t1 t2 t3 t4 t5 t6 tw1 tw2 Va T Ts Te T/2 Tr Tf Vs Tos Tdtx Zo
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Min
Typ
Max
Unit
Input data set-up time Encode clock set-up time Encode envelope set-up time Encode envelope turn-off time Transmitter activation set-up time Transmitter deactivation hold-time 20 MHz gated CK pulse width high Encoder shift CK pulse width high Output Signals Output amplitude (see Figure 2) Pulse period Width of 1st positive half bit Width of last half bit Half pulse period Pulse rise time Pulse fall time Voltage overshoot Offset Voltage 2T after last zero crossing Delay from 20 MHz clock input to data output on transformer secondary Output Impedance
2
10 10 10 10 150 50 20 45 2.75 97 45 47 47 50 3.25 100
40 40 40 35
ns ns ns ns ns ns
30 55 3.75 103 65 65 53 2.0 2.0 350 150 20 55 80
ns ns V ns ns ns ns V/ns V/ns mV mV ns
70
75
SCDCT1815 REV A 6/12/98 Plainview NY (516) 694-6700
Aeroflex Circuit Technology
BIT 0 NRZ Serial Input t1
BIT 1
BIT 2
BIT N
P1 = 50ns 0.1% P2 = 100ns 0.1%
Encoder Shift Clock Input
t2
t W2
P2 20 MHz GATED Clock t3 NRZ Envelope
3
t W1 P1 t4
t5 Encoder Enable Power Management Pin Tf
t6
2T Transmitter Output T dTX Va VS V US 10% 10% Te TOS 90% 90% T
SCDCT1815 REV A 6/12/98 Plainview NY (516) 694-6700
T/2 T
Tr
Figure 2 Encoder - Transmitter Timing
1st Data BIT Manchester II Receiver Data t1
2nd Data BIT
3rd Data BIT
4th Data BIT
5th Data BIT
Decoded Data Envelope R X Data Data R CK R
t6 t5
t7
t2
t3
t4 t5
Figure 3 Receiver / Decode Timing
Symbol
Parameter / Condition
Min
Nom
Max
Units
t1 t2 t3 t4 t5 t6 t7 t8
Envelope delay time Data decode delay Clock low transition delay ClockR high time ClockR low time Envelope off delay Receiver strobe enable to input data set-up time Receiver strobe disable to input data hold-time
35 35 120 5 20
45 115 130 50 50 -
100 125 65 65 270 -
nsec nsec nsec nsec nsec nsec nsec ?
Power Management Functional Table
Encoder Enable (Pin 10) Power Management Input (Pin 9) Receiver Status Transmitter Status
0 X 1
0 1 X
Active Active Active
Standby Active Active
Power management timing see Figure 2.
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SCDCT1815 REV A 6/12/98 Plainview NY (516) 694-6700
Functional Description and Pinout
Pin # Pin Name Function Load or Drive
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
No connection No connection XFMR secondary/ RX data input Test Point Test Point Test Point -5 Volts RX strobe Power management input Encoder enable Case/signal GND Case/signal GND Decoded data envelope TP3 test point TP1 test point TP2 test point -5 Volts TP4 test point ClockR No connection Decoded DataR No connection +5 volts +5 volts 10 MHz encoder shift clock NRZ serial input data Encode envelope 20 MHz gated clock (encoder)
Transmitter-receiver I/O pin No connection permitted No connection permitted No connection permitted Low level disables receiver Controls transmitter power consumption in conjunction with pin 10 Controls transmitter power consumption in conjunction with pin 9 3 S loads 1 S load 1 S load
High after reception of first half bit; goes low after reception of last half bit (normally low in inactive state) Alignment point: no electrical connection permitted Alignment point: no electrical connection permitted Alignment point: no electrical connection permitted Alignment point: no electrical connection permitted Reconstructed clock; one clock pulse per input bit received NRZ reconstructed data. Sampled on clockR rising edge
4 S drive
3 S drive 3 S drive
One cycle required per data bit. Must be high in first half of bit cell Serial input to be Manchester encoded with the 20 MHz gated CK Must be high to enable transmission; must go low before reception of last 20 MHz positive edge to complete transmission Each bit to be encoded requires two positive edges of the 20 MHz CK. These edges must occur at 25ns and 75ns into the bit cell. The end of transmission requires an additional edge in conjunction with a logic low on the encode envelope. tR, tF < 5nsec. Logic low resets encoder
1 S load 1 S load 1 S load 1 S load
29 30 31 32 33 34
Master reset reset pulse <15 nsec No connection No connection XFMR secondary/ RX DATA input XFMR secondary XFMR primary/ TX DATA output
2 S load
Transmitter-Receiver I/O pin Secondary isolated winding, same phase as outer conducter Transformer lead for connection to outer conductor of tri-axial
5 SCDCT1815 REV A 6/12/98 Plainview NY (516) 694-6700
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Load and Drive Definitions 1 S load: requires IIL = -2mA max., VIL = 0.8V max IIH = 50A max., VIH = 2.5V min CIN < 15 pf 1 S drive: IOH = 50A min., VOH = 2.5V min IOL = -2 mA min., VOL = 0.5V max Power Consumption Current (mA) Typ ICC Standby mode IEE Standby mode ICC 100% Transmission IEE 100% Transmission 235 75 447 242 Max 305 100 585 315
Absolute Maximum Ratings VCC (Pins 23, 24) +7 Volts Max VEE (Pins 7, 17) -7 Volts Max Logic Input Voltage Applied: Logic Low -1.2V @ 10mA Max Logic High +5.5 Volts Damage will not result from cable open circuits or short circuits (on the transformer primary) of the following types: * Line-to-line * Line-to-ground * 120V AC 60Hz common mode signal Environmental Parameters Operating Temperature -55C to +100C Case Storage Temperature -55C to +150C Screened per individual test methods of MIL-STD-883.
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SCDCT1815 REV A 6/12/98 Plainview NY (516) 694-6700
CIRCUIT TECHNOLOGY
Ordering Information
Model Number
CT1815 CT1815FP
Package
Plug-in Package Flat Package
Plug-In Package Outline
1.200 .005 Pin 1 & ESD Designator 1.810 MAX .200 .270 .010 .100 .005 TYP .018 .002 DIA .120 .010 Both Sides
.100 TYP Both Sides
(17 Pins/Side)
Flat Package Outline
.015 .003 .100 .005 .400 MIN .180 MAX
1.410 MAX Lead 1 & ESD Designator
1.810 MAX
.010 .002
Aeroflex Circuit Technology 35 South Service Road Plainview New York 11830
Specifications subject to change without notice.
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Telephone: (516) 694-6700 FAX: (516) 694-6715 Toll Free Inquiries: 1-(800)THE-1553
SCDCT1815 REV A 6/12/98 Plainview NY (516) 694-6700

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