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CMX469A
1200/2400/4800 Baud FFSK/MSK Modem
D/469A/2 May 2001 Provisional Issue
Features
* Full-Duplex FFSK/MSK Modem with Separate Rx and Tx Enable Functions * Pin Selectable Data Rates: 1200, 2400 or 4800 Baud * Pin Selectable Xtal/Clock Inputs: 1.008MHz or 4.032MHz * Clock Recovery Facility * Carrier Detect Facility * Low Power Operation (2.0mA typ. at 3.0V)
Applications
* Data-Over Radio * Personal/Cordless Telephone * Radio and General Applications * Narrowband Coax Data Channels * Two Way Radio (MPT1327) Signalling * Portable Data Terminals
1.1
Brief Description
The CMX469A is a single-chip CMOS LSI circuit which operates as a full-duplex 1200, 2400 or 4800 baud FFSK/MSK modem. The mark and space frequencies are 1200/1800, 1200/2400 and 2400/4800 Hz respectively. Tone frequencies are phase continuous; transitions occur at the zero crossing point. A common Xtal oscillator with a choice of two clock frequencies (1.008MHz or 4.032MHz) provides baud-rate, transmit frequencies, and Rx and Tx synchronization. The transmitter and receiver operate entirely independently, including the individual section powersave functions. The CMX469A includes on-chip circuitry for Carrier Detect and Rx Clock recovery, both of which are made available as output pins. Rx, Tx and Carrier Detect paths contain bandpass filters to optimise signal conditions in each section of the modem. The CMX469A demonstrates good sensitivity and bit-error-rate under adverse signal conditions. The Carrier Detect time constant is set by an external capacitor, so that the product's performance can be optimised in high noise environments. This low-power device operates from a single supply between 2.7V and 5.5V, requires few external components and is available in a wide variety of plastic packages.
(c) 2001 Consumer Microcircuits Limited
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
CONTENTS Section 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Page Features and Applications.......................................................................2 Brief Description .......................................................................................2 Block Diagram ...........................................................................................4 Signal List...................................................................................................5 External Components ...............................................................................7 General Description ..................................................................................8 Application Notes......................................................................................9 Performance Specification.....................................................................10 1.7.1 Electrical Performance..............................................................10 1.7.2 Packaging....................................................................................16
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
1.2
Block Diagram
Figure 1 Block Diagram
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
1.3
D3
Signal List
CMX469A E2 P6 Signal Description
Pin No. 1
Pin No. 1
Pin No. 1
Name
Type
CLOCK/XTAL
I/P
The input to the on-chip inverter, for use with either a 1.008MHz or a 4.032MHz Xtal or an external clock. Clock frequency selection is by means of the CLOCK RATE pin. This affects the operational data rate of the device. Operation of any CML microcircuit without a Xtal or clock input may cause device damage. The output of the on-chip inverter. A squarewave, produced on-chip, to synchronize the input of logic data and transmission of the FFSK/MSK signal. When the transmitter is enabled, this pin outputs the FFSK/MSK signal. With the transmitter disabled, this pin is set to a high-impedance state. The serial logic data to be transmitted is input to this pin. A logic `0' will enable the transmitter. A logic `1' at this input will put the transmitter into powersave whilst forcing Tx SYNC OUTPUT to a logic `1' and Tx SIGNAL OUTPUT to a high-impedance state. This pin is internally pulled to VDD.
2 3
2 3
2 3
XTALN Tx SYNC O/P
O/P O/P
4
5
5
Tx SIGNAL O/P
O/P
5 6
7 8
6 7
Tx DATA I/P Tx ENABLEN
I/P I/P
7
9
8
BANDPASS O/P Rx ENABLE VBIAS
O/P
The output of the Rx Bandpass Filter. This output impedance is typically 10k and may require buffering prior to use. The control of the Rx function The output of the on-chip analogue bias circuitry. Held internally at VDD/2, this pin should be decoupled to VSS by a capacitor (C2). This bias voltage is maintained under all powersave conditions.
8 9
10 11
9 10
I/P BI
10 11 12
12 13 14
11 12 13
VSS UNCLOCKED DATA O/P CLOCKED DATA O/P
PWR O/P O/P
Negative supply rail (GND). The recovered asynchronous serial data output from the receiver. The recovered synchronous serial data output from the receiver. Data is latched out by the recovered clock, available at the Rx SYNC O/P.
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
CMX469A D3 E2 P6 Signal Description
Pin No. 13 14 15 16
Pin No. 15 16 18 19
Pin No. 14 15 17 16
Name CARRIER DETECT O/P Rx SIGNAL I/P Rx SYNC O/P 1200/2400 BAUD SELECT
Type O/P I/P O/P I/P When an FFSK/MSK signal is being received this output is a logic `1'. The FFSK/MSK signal input for the receiver. This input should be coupled via a capacitor, C3. A flywheel squarewave output. This clock will synchronize to incoming Rx FFSK/MSK data. A logic `1' on this pin selects the 1200 baud option. Tone frequencies are: one cycle of 1200Hz represents a logic `1,' one-and-a-half cycles of 1800Hz represents a logic `0.' A logic `0' on this pin selects the 2400 baud option. Tone frequencies are: one-half cycle of 1200Hz represents a logic `1,' one cycle of 2400Hz represents a logic `0.' This function is also used, in part, to select the 4800 baud option. This pin has an internal 1M pullup resistor.
17
20
18
4800 BAUD SELECT
I/P
A logic `1' on this pin combined with a logic `0' on the 1200/2400 BAUD SELECT pin will select the 4800 baud option (1M pulldown resistor). Tone frequencies are: one-half cycle of 2400Hz represents a logic `1,' one cycle of 4800Hz represents a logic `0.' Operation at 4800 baud is only achieved by using a 4.032MHz Xtal or clock. A logic input to select and allow the use of either a 1.008MHz or 4.032MHz Xtal/clock. Logic `1' = 4.032MHz, logic `0' = 1.008MHz. This input has an internal pulldown resistor (1.008MHz). Part of the carrier detect integration function. The value of C4 connected to this pin will affect the carrier detect response time and hence noise performance. Positive supply rail. A single 2.7 to 5.0 volt supply is required. This pin should be decoupled to VSS by a capacitor (C5).
18
21
19
CLOCK RATE
I/P
19
22
20
CARRIER DETECT TIME CONSTANT
BI
20
24
22
VDD
PWR
4, 6, 17, 23 Notes:
4, 21
No internal connection, do not use.
I/P = Input
O/P = Output
BI = Bidirectional
PWR = Power
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
1.4
External Components
Component R1 C1 C2 C3 C4 C5 C6 C7 X1
Value 1.0M 33.0pF 1.0F 0.1F 0.1F 1.0F 1.0F 33.0pF 1.008MHz or 4.032MHz
Notes: 1. VBIAS may be decoupled to VSS and VDD using C2 and C6 when input signals are referenced to the VBIAS pin. For input signals referenced to VSS, decouple VBIAS to VSS using C2 only. 2. The performance of the Carrier Detect function will be affected by the nature of the noise spectrum in the received channel. The value of C4 determines the Carrier Detect Time Constant. A long time constant results in improved noise immunity but increased response time. C4 may be varied to trade-off response time for noise immunity. 3. A 4.032MHz Xtal/clock is required for 4800 Baud operation. Figure 2 Recommended External Components
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
1.5
General Description
The CMX469A has two sections, apart from the Xtal oscillator circuit and clock dividers. These sections may be independently powersaved. Transmitter The transmitter is enabled by taking Tx EnableN low. Serial data applied to Tx Data Input is sampled internally and an FFSK/MSK sequence is generated. After filtering, this is output at Tx Signal O/P and the transmit clock derived from this signal is output at Tx Sync O/P. Receiver The receiver is enabled by taking Rx Enable high. The signal applied to Rx Signal I/P is filtered and recovered as serial data from the Unclocked Data O/P. A flywheel synchroniser is used to extract a clock from the recovered serial data stream. The clock is available at Rx Sync O/P and the retimed serial data is available at Clocked Data O/P. The integrated peak values of the Rx amplitude are compared with out-of-band noise levels and used to make a signal-to-noise assessment, which is available at Carrier Detect O/P. A Bandpass O/P is also available from the output of the first Rx filter stage, but will require buffering before use.
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
1.6
Application Notes
Rx Enable The control of the relevant outputs with reference to the Rx Enable input is described below: Rx Enable `1' `0' Rx Function Enabled Powersave Clock Data O/P Enabled `0' Carrier Detect O/P Enabled `1' or `0' Rx Sync Out Enabled `1' or `0'
After enabling the Receiver, a time of at least 8 bit periods plus 2ms should be allowed for the Carrier Detect circuit to stabilise and give a valid output. Operational Data Rate Configurations Operational Data Rate Configurations are as described below: Xtal/Clock Frequency Clock Rate 1200/2400 Select 4800 Select Baud Rate `0' `1' `0' 1200
1.008MHz `0' `0' `0' 2400 `1' `1' `0' 1200
4.032MHz `1' `0' `0' 2400 `1' `0' `1' 4800
Test Set Up
Figure 3 Suggested CMX469A Test Set-Up
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
1.7
1.7.1
Performance Specification
Electrical Performance
Absolute Maximum Ratings Exceeding these maximum ratings can result in damage to the device. Min. -0.3 -0.3 -30 -20 Max. 7.0 VDD + 0.3 +30 +20 Units V V mA mA
Supply (VDD - VSS) Voltage on any pin to VSS Current into or out of VDD and VSS pins Current into or out of any other pin
D3 Package Total Allowable Power Dissipation at Tamb = 25C ... Derating Storage Temperature Operating Temperature E2 Package Total Allowable Power Dissipation at Tamb = 25C ... Derating Storage Temperature Operating Temperature P6 Package Total Allowable Power Dissipation at Tamb = 25C ... Derating Storage Temperature Operating Temperature
Min.
-55 -40 Min.
Max. 800 13 +125 +85 Max. 320 5.3 +125 +85 Max. 800 13 +125 +85
Units mW mW/C C C Units mW mW/C C C Units mW mW/C C C
-55 -40 Min.
-55 -40
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
Operating Limits Correct operation of the device outside these limits is not implied. Notes Supply (VDD - VSS) Operating Temperature Xtal Frequency Min. 2.7 -40 4.028 Max. 5.5 +85 4.036 Units V C MHz
1
Note 1: A Xtal frequency of 1.008MHz (1200/2400 baud only) or 4.032MHz is required for correct operation. A frequency tolerance of 0.1% is recommended, but ultimately the tolerance selected will depend upon system requirements.
Operating Characteristics For the following conditions unless otherwise specified: VDD = 2.7V at Tamb = 25C and VDD = 3.0V to 5.5V at Tamb = -40C to +85C, Xtal/Clock Frequency = 4.032MHz, Bit Rate = 1200 baud, Rx Input Level = 300mVrms. Notes Static Values IDD Rx Enabled, Tx Disabled (VDD = 5.0V) (VDD = 5.0V) IDD Rx and Tx Enabled (VDD = 5.0V) IDD Rx and Tx Disabled IDD Rx Enabled, Tx Disabled (VDD = 3.0V) (VDD = 3.0V) IDD Rx and Tx Enabled (VDD = 3.0V) IDD Rx and Tx Disabled Logic `1' Level Logic `0' Level Digital Output Impedance Analogue and Digital Input Impedance Tx Output Impedance (VDD = 5.0V) Dynamic Values Receiver Signal Input Dynamic Range SNR = 50dB Bit Error Rate at SNR = 12dB 1200 Baud 2400 Baud 4800 Baud Bit Error Rate at SNR = 20dB 1200/2400/4800 Baud Receiver Synchronization at SNR = 12dB probability of bit 16 being correct 2 2 2 2 2 2 1 1 Min. 70% 100 Typ. 3.6 4.5 650 1.5 2.0 300 4.0 0.6 Max. 30% 1.0 Units mA mA A mA mA A VDD VDD k k k
3, 4 4, 5
100 -
230 2.5 1.5 1.5 <1.0 0.995
1000 -
mVrms 10-4 10-3 10-3 10-8
4, 5 7 -
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
Notes Carrier Detect Sensitivity Probabilty of CD being High after bit 16: with SNR = 12dB with 230mVrms Noise and No Signal Transmitter Output Tx Output Level Output Level Variation for 1200/1800Hz or 1200/2400Hz or 2400/4800Hz Output Distortion 3rd Harmonic Distortion Isochronous Distortion 1200Hz - 1800Hz/1800Hz - 1200Hz 1200Hz - 2400Hz/2400Hz - 1200Hz 2400Hz - 4800Hz/4800Hz - 2400Hz Logic `1' Carrier Frequency 1200 Baud 2400 Baud 4800 Baud Logic `0' Carrier Frequency 1200 Baud 2400 Baud 4800 Baud 3 1, 7, 8 9 9
Min.
Typ.
Max.
Units
-
0.995 0.05
150
mVrms
1
0
775 3.0 2.0 25.0 20.0 10.0 1200 1200 2400 1800 2400 4800
+/-1.0 5.0 3.0 40.0 30.0 20.0 -
mVrms dB % % s s s Hz Hz Hz Hz Hz Hz
10 10
-
6 6 6 6 6 6
-
Notes: 1. Measured at V
DD
= 5.0 volts. Signal levels and thresholds are proportional to V
DD.
2. Excludes any current drawn by external components, but includes current drawn by the crystal components. 3. See Figure 6 (Typical Variation of BER with Input Signal Level). 4. SNR = Signal-to-Noise Ratio in the Bit-Rate Bandwidth. 5. See Figure 7 (Typical Rx BER vs Signal-to-Noise Ratio). 6. Dependent upon Xtal tolerance. 7. With an alternating (1010...) pattern. 8. Measured with a 150mVrms input signal (no noise). 9. A signal level of 230mVrms is used in C.D. probability measurements. Noise bandwidth is 5kHz (1200/2400 baud operation) or 8kHz (4800 baud operation). See Section 1.4, Note 2 for details on optimising noise immunity. 10. For an unmodulated carrier.
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
Interface Timing Diagrams
tESET
Tx ENABLE
Tx SYNC
t DSET
Tx DATA
DC DV = = Don't Care Data Valid
t DH
t TDR
DV DC DV
tTDR
DC
DC
DV
DC
t TxD
OPEN CIRCUIT OPEN CIRCUIT
1200 BAUD Tx OUTPUT
2400 BAUD Tx OUTPUT
OPEN CIRCUIT
OPEN CIRCUIT
TX DATA must be valid at the time of the rising edge of TX SYNC. Therefore the optimum time to change TX DATA is on the falling edge of TX SYNC. Figure 4 Transmitter Timing
Rx SIGNAL I/P 2400/4800 BAUD
LOGIC '1'
LOGIC '0'
Rx SIGNAL I/P 1200 BAUD
t ID
1
Rx SYNC O/P (1200Hz)
0
t RDR
1
Undetermined State
CLOCKED DATA O/P
0
LOGIC '1'
LOGIC '0'
The optimum time to sample the CLOCKED DATA O/P is on the falling edge of RX SYNC O/P. Figure 5 Receiver Timing
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
1.7.1
Electrical Performance (continued)
Interface Timings
tESET
tDSET tDH tTXD tTDR tRDR
Notes
2
1
Min.
2.0
2.0 2.0 -
Typ.
1.2 833 1.5 -
Max.
800
-
Units
s
s s s
Tx Delay, Signal to Disable Time
Data Set-Up Time Data Hold Time Tx Delay to O/P Time Tx Data Rate Period Rx Data Rate Period Undetermined State (see Figure 5)
2 2
800 -
865 2.0 -
s s s ms
tID
Internal Rx Delay
Notes:
1. Consider the Xtal/Clock tolerance. 2. 1200 Baud example.
1
x 10 -1
*
BIT RATE BANDWIDTH
1
BIT ERROR RATE
x 10 -2
10 d
12
B
SN R
SN R
*
dB
*
1
x 10
-3
dB 20 SN R
1
x 10 -4
*
1
x 10 -5 50 100 150 200 250 300 500
INPUT SIGNAL
700
LEVEL
800
(mVrms)
Figure 6 Typical Variation of Bit Error Rate with Input Level
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
Figure 7 Typical Rx Bit Error Rate vs Signal-to-Noise Ratio
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
1.7.2
Packaging
Figure 8 D3 Mechanical Outline: Order as part no. CMX469AD3
Figure 9 E2 Mechanical Outline: Order as part no. CMX469AE2
(c) 2001 Consumer Microcircuits Limited
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D/469A/2
1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
Figure 12 P6 Mechanical Outline: Order as part no. CMX469AP6
Handling precautions: This product includes input protection, however, precautions should be taken to prevent device damage from electro-static discharge. CML does not assume any responsibility for the use of any circuitry described. No IPR or circuit patent licences are implied. CML reserves the right at any time without notice to change the said circuitry and this product specification. CML has a policy of testing every product shipped using calibrated test equipment to ensure compliance with this product specification. Specific testing of all circuit parameters is not necessarily performed.
Oval Park - LANGFORD MALDON - ESSEX CM9 6WG - ENGLAND
Telephone: +44 (0)1621 875500 Telefax: +44 (0)1621 875600 e-mail: sales@cmlmicro.co.uk http://www.cmlmicro.co.uk
CML Microcircuits
COMMUNICATION SEMICONDUCTORS
CML Product Data
In the process of creating a more global image, the three standard product semiconductor companies of CML Microsystems Plc (Consumer Microcircuits Limited (UK), MX-COM, Inc (USA) and CML Microcircuits (Singapore) Pte Ltd) have undergone name changes and, whilst maintaining their separate new names (CML Microcircuits (UK) Ltd, CML Microcircuits (USA) Inc and CML Microcircuits (Singapore) Pte Ltd), now operate under the single title CML Microcircuits. These companies are all 100% owned operating companies of the CML Microsystems Plc Group and these changes are purely changes of name and do not change any underlying legal entities and hence will have no effect on any agreements or contacts currently in force. CML Microcircuits Product Prefix Codes Until the latter part of 1996, the differentiator between products manufactured and sold from MXCOM, Inc. and Consumer Microcircuits Limited were denoted by the prefixes MX and FX respectively. These products use the same silicon etc. and today still carry the same prefixes. In the latter part of 1996, both companies adopted the common prefix: CMX. This notification is relevant product information to which it is attached.
Company contact information is as below:
CML Microcircuits (UK)Ltd
COMMUNICATION SEMICONDUCTORS
CML Microcircuits (USA) Inc.
COMMUNICATION SEMICONDUCTORS
CML Microcircuits (Singapore)PteLtd
COMMUNICATION SEMICONDUCTORS
Oval Park, Langford, Maldon, Essex, CM9 6WG, England Tel: +44 (0)1621 875500 Fax: +44 (0)1621 875600 uk.sales@cmlmicro.com www.cmlmicro.com
4800 Bethania Station Road, Winston-Salem, NC 27105, USA Tel: +1 336 744 5050, 0800 638 5577 Fax: +1 336 744 5054 us.sales@cmlmicro.com www.cmlmicro.com
No 2 Kallang Pudding Road, 09-05/ 06 Mactech Industrial Building, Singapore 349307 Tel: +65 7450426 Fax: +65 7452917 sg.sales@cmlmicro.com www.cmlmicro.com
D/CML (D)/1 February 2002

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