CML Semiconductor FX469 1200/2400/4800 Baud FFSK Modem PRODUCT INFORMATION
Contents
1. Veias Vss O NOANA OUO N FX469J CARRIER DETECT TIME CONSTANT CLOCK RATE 4800 BAUD SELECT Rx SYNC O P 1200 2400 BAUD SELECT gt C3 Rx SIGNAL I P CARRIER DETECT OF CLOCKED DATA O P UNCLOCKED BATA O P gt Component Value Tolerance Notes 1 0MW 33 0pF 1 0uF 0 1uF 0 1uF 1 0uF 1 0uF 33 0pF 1 008MHz or 4 032MHz 10 20 10 20 on A R C C C C C C C X See Clock Rate Pin N Fig 2 External Components MILLI AMMETER PREAMBLE amp PSEUDO RANDOM DATA GENERATOR FX469 TRANSMITTER components as Fig 2 Tx SYNC 1 Vaiss May be decoupled to V and Vp using C and C when input signals are referenced to the Vps pin For input signals referenced to V decouple V to Vss using C only ss BIAS Use C when input signals are referenced to V to decouple V The value of C determines the Carrier Detect time constant A long time constant results in improved noise immunity but increased response time C may be varied to trade off response time for noise immunity C reduces Xtal voltage overshoot Refer to CML Xtal Application Note D XT 2 December 1991 BUFFER INTERFACE CIRCUIT 5kHz BW noise gen TRUE RMS OSCILLOSCOPE Fig 3 Suggested FX469 Test Set Up VOLTMETER MILLI AMMETER CLOCKED DATA O P FX469 fe RECEIVER ERROR DETECTOR TELEP2. 12dB 5 9 0 995 OdB Noise No Signal 9 0 05 Specification Characteristics See Note Min Typ Max Unit Transmitter Output Tx Output Level 775 mVrms Output Level Variation 1200 1800Hz or 1200 2400Hz or 2400 4800Hz 0 1 0 dB Output Distortion 3 0 5 0 3rd Harmonic Distortion 2 0 3 0 Logic 1 Carrier Frequency 1200 Baud 6 1200 Hz 2400 Baud 6 1200 Hz 4800 Baud 6 2400 Hz Logic 0 Carrier Frequency 1200 Baud 6 1800 Hz 2400 Baud 6 2400 Hz 4800 Baud 6 4800 Hz Isochronous Distortion 1200Hz 1800HZz 1800Hz 1200Hz 25 0 40 0 Us 1200Hz 2400HZ 2400Hz 1200Hz 20 0 30 0 Us 2400Hz 4800Hz 4800Hz 2400Hz 10 0 20 us Notes 1 With reference to V 5 0 volts 2 Xtal frequency type and tolerance depends upon system requirements 3 See Figure 5 variation of BER with Input Signal Level 4 SNR Signal to Noise Ratio in the Bit Rate Bandwidth 5 See Figure 2 6 Dependent upon Xtal tolerance 7 10101010101 01 pattern 8 Measured with a 150mVrms input signal no noise 1200 2400 baud operation 9 Reference 0dB level for C D probability measurements is 230mVrms 10 For 1200 and 2400 baud operation only when operating at 4800 baud the Carrier Detect output should be ignored BIT RATE BANDWIDTH T o oc O a fia m a 50 100 150 500 700 800 INPUT SIGNAL LEVEL mVrms Fig 6 Typical Variation of Bit Error Rate with
3. Input Level Application Information IDEAL COHERENT FFSK 10 Fig 7 Rx Bit Error Rate vs Signal to Noise Ratio Package Outlines The FX469 is available in the package styles outlined below Mechanical package diagrams and specifications are detailed in Section 10 of this document Pin 1 identification marking is shown on the relevant diagram and pins on all package styles number anti clockwise when viewed from the top FX469DW 20 in plastic S O I C D3 8 9 10 11 12 13 14 15 16 SNR dB BIT RATE BANDWIDTH lin scale Handling Precautions The FX469 is a CMOS LSI circuit which includes input protection However precautions should be taken to prevent static discharges which may cause damage FX469J 22 pin rdip DIL JB NOT TO SCALE 12 95mm 7 59mm Max Body Length Max Body Width NOT TO SCALE lt a Max Body Length Max Body Width 27 38mm 9 75mm Package Outlines FX469LG 24 pin quad plastic encapsulated FX469LS 24 lead plastic leaded chip bent and cropped LL carrier 12 NOT TO SCALE NOT TO SCALE a J Y If US HJ MS Max Body Length 10 25mm Max Body Length 10 40mm Max Body Width 10 25mm Max Body Width 10 40mm FX469P6 22 pin plastic DIL Ordering Information FX4 pi O 1 C 69DW 20 pin suriace mount S O 1 C NOT TO SCALE FX469J 22 pin cerdip DIL FX469LG 24 pin quad plastic encapsulated bent and cropped il FX469LS 24 lea
4. 2576 FX 469D S t ny FA CML Semiconductor Products PRODUCT INFORMATION 1200 2400 4800 Baud FX469 FFSK Modem Features Selectable Data Rates 1200 2400 and 4800 Baud Full Duplex FFSK Rx and Tx Bandpass Filters Clock Recovery and Carrier Detect Facilities Rx and Tx Enable Functions Tx GENERATOR Tx FILTER Tx DATA I P Publication D 469 6 April 1998 Pin Selected Xtal Clock Inputs 1 008MHz or 4 032MHz Radio and General Applications Data Over Radio PMR and Cellular Signalling Portable Data Terminals Personal Cordless Telephone Tx SIGNAL O P gt ML H Tx ENABLE i y Tx SYNC O P gt CLOCK RATE XTAL CLOCK poe ee CLOCK OSCILLATOR owioer XTAL 1200 2400 BAUD SELECT J 4800 BAUD SELECT os RETRIGGERABLE Rx ENABLE Ax FILTER LIMITER MONOSTABLE gt BANDPASS O DATA LIMITER HETER UNCLOCKE FX469 Rx SIGNAL I P Ory gt aS F a DIGITAL 7 gt FILTER x DATA OIP NY RECTIFIER CLOCKE DIGITAL PLL DATA O gt K RECTIFIER NOISE FILTER Rx SYNC O I gt CARRIER DETECT O gt e WN e gt xX a S N COMPARATOR CARRIER DETECT TIME CONSTANT Fig 1 Functional Block Diagram Brief Description The FX469 is a single chip GMOS LS
5. HONE CHANNEL SIMULATOR with attenuator components as Fig 2 CARRIER DETECT O P HIGH DETECTOR TRUE RMS VOLTMETER gt ie toy toseT lt Tx DATA DC Don t Care DV Data Valid t gt ee OPEN CIRCUIT a a OPEN CIRCUIT 1200 BAUD Tx OUTPUT OPEN CIRCUIT F 7 C OPEN CIRCUIT 2400 BAUD Tx OUTPUT Fig 4 Transmitter Timing Characteristics Note Min Typ Max Unit Tx Delay Signal to Disable Time tiser 3 2 0 800 uS Data Set Up Time br 1 2 0 us Data Hold Time toy 2 0 us Tx Delay to O P Time tan z 1 2 s us Tx Data Rate Period 3 833 E us Rx Data Rate Period fioa 3 800 865 us Undetermined State 2 0 us Internal Rx Delay ty 1 5 ms 1 Consider the Xtal Clock tolerance 2 All Tx timings are related to the Tx Sync Output 3 1200 baud example Rx SIGNAL P 2400 4800 BAUD LOGIC 1 i LOGIC 0 Rx i SIGNAL I P 1200 BAUD Rx SYNC O P 1200Hz Undetermined State BATA OP Locic Loaic 0 Fig 5 Rx Timing Diagram ps Specification Absolute Maximum Ratings Exceeding the maximum rating can result in device damage Operation of the device outside the operating limits is not implied Supply voltage 0 3 to 7 0V Input voltage at any pin ref V OV 0 3 to V 0 3V Sink source current Supply pins 30mA other pins 20mA Total device dissipation T 25 C 800mW Max Derating 10mW C Operating temperature ra
6. I circuit which operates as a full cuplex pin selectable 1200 2400 or 4800 baud FFSK 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 Employing a camon Xtal oscillator with a choice of two clock frequencies 1 008MHz or 4 032MHz to provide baud rate transmit frequencies and Rx and Tx synchronization the transmitter and receiver operate entirely independently including individual section powersave functions The FX469 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 each contain a bandpass filter to ensure the provision of ootimm signal conditions both in the modem and for the Tx modulation circuitry The FX469 demonstrates a high sensitivity and good bit error rate under adverse signal conditions the carrier detect time constant is set by an extemal capacitor whose value should be arranged as required to further enhance this product s perfomance in high noise environments This low power device requires few extemal components and is available in small outline plastic S O 1 C and cerdip DIL packages Pin Number Function FX469 DW LG LS J P6 1 1 1 Xtal Clock The input to the on chip inverter for use with either a 1 008MHz or a 4 0832MHz Xtal or external clock Clock frequency selec
7. d plastic leaded chip carrier 2 FX469P6 22 pin plastic DIL Max Body Length 27 94mm Max Body Width 9 14mm CML does not assume any responsibility for the use of any circuitry described No circuit patent licences are implied and CML reserves the right at any time without notice to change the said circuitry
8. nge FX469DW LG LS P6 30 C to 70 C plastic FX469J 30 C to 85 C cerdip Storage temperature range FX469DW LG LS P6 40 C to 85 C plastic FX469J 55 C to 125 C cerdip Operating Limits All device characteristics are measured under the following conditions unless otherwise specified Vbo 5 0V Tane 25 C Audio Level 0dB ref 300mVrms Xtal Clock 4 032MHz Signal to Noise Ratio measured in the Bit Rate Bandwidth Baud Rate 1200 baud Characteristics See Note Min Typ Max Unit Static Values Supply Voltage 4 5 5 0 5 5 V Supply Current Rx Enabled Tx Disabled 3 6 mA Rx and Tx Enabled 4 5 mA Rx and Tx Disabled 650 uA Logic 1 Level 1 4 0 5 V Logic 0 Level 1 1 0 V Digital Output Impedance 4 0 kw Analogue and Digital Input Impedance 100 kw Tx Output Impedance 0 6 1 0 kw On Chip Xtal Oscillator Rn 10 0 Mw Bint 5 0 15 0 kw Inverter d c Voltage Gain 10 0 20 0 V V Gain Bandwidth Product 4 1 MHz Xtal Frequency 2 a 1 008 MHz Xtal Frequency 2 4 032 5 MHz Dynamic Values Receiver Signal Input Dynamic Range SNR 50dB 3 4 100 230 1000 mVrms Bit Error Rate SNR 12dB 4 1200 Baud 2 5 104 2400 Baud 1 5 10 4800 Baud 1 5 108 SNR 20dB 4 1200 2400 4800 Baud lt 1 0 108 Receiver Synchronization SNR 12dB 7 Probability of Bit 16 Being Correct 0 995 Carrier Detect 5 10 Sensitivity 7 8 150 mVrms Probabilty of C D Being High After Bit 16 SNR
9. on ClockDataO P Carrier Detect Rx Sync Out 4 Enabled Enabled Enabled Enabled 0 Powersave 0 0 1 or 0 9 11 10 Visas The output of the on chip analogue bias circuitry Held internally at V p 2 this pin should be decoupled to V by a capacitor C See Figure 2 This bias voltage is maintained under all powersave conditions 10 12 11 Vs Negative supply rail GND Pin Number Function FX469 DW LG LS_ J P6 11 13 12 Unclocked Data O P The recovered asynchronous serial data output from the receiver 12 14 13 Clocked Data O P The recovered synchronous serial data output from the receiver Data is latched out by the recovered clock available at the Rx Sync O P See Figure 5 13 15 14 Carrier Detect O P When an FFSK signal is being received this output is a logic 1 14 16 15 Rx Signal I P The FFSK signal input for the receiver This input should be coupled via a capacitor C 15 18 17 Rx Sync O P A flywheel squarewave output This clock will synchronize to incoming Rx FFSK data See Figure 5 16 19 16 1200 2400 Baud Select 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 represen
10. tion is by the Clock Rate input pin The selection of this frequency will affect the operational Data Rate of this device Refer to Baud Selection information on the next page Operation of any CML microcircuit without a Xtal or clock input may cause device damage To minimise damage in the event of a Xtal drive failure it is recommended that the power rail V is fitted with a current limiting device resistor or fast reaction fuse 2 2 2 XtalN Output of the on chip inverter 3 3 3 Tx Sync O P A squarewave produced on chip to synchronize the input of logic data and transmission of the FFSK signal See Figure 4 4 5 5 Tx Signal O P When the transmitter is enabled this pin outputs the 140 step pseudo sinewave FFSK signal See Figure 4 With the transmitter disabled this output is set to a high impedance state 5 7 6 Tx Data I P Serial logic data to be transmitted is input to this pin 6 8 7 Tx EnableN A logic 0 will enable the transmitter See Figure 4 A logic 1 at this input will put the transmitter into powersave whilst forcing Tx Sync Out to a logic 1 and Tx Signal Out to a high impedance state This pin is internally pulled to Vp 7 9 8 Bandpass O P The output of the Rx Bandpass Filter This output impedance is typically 10kw and may require buffering prior to use 8 10 9 Rx Enable The control of the Rx function The control of other outputs is given below Rx Enable RxFuncti
11. ts a logic 0 This function is also used in part to select the 4800 baud option This pin has an internal 1Mw pullup resistor Operational Data Rate Configurations are illustrated in the table below Xtal Clock Frequency 1 008MHz 4 032MHz Clock Rate pin 0 0 1 1200 2400 Select pin 1 0 1 4800 Select pin 0 0 0 Baud Rate 1200 2400 1200 2400 4800 17 20 18 4800 Baud Select A logic 1 on this pin combined with a logic 0 on the 1200 2400 Baud Select pin will select the 4800 option 1Mw pulldown resistor Tone frequencies are one half cycle of 2400Hz represents a logic 1 one cycle of 4800Hz represents a logic 0 This state can only be achieved using a 4 032MHz Xtal input 18 21 19 Clock Rate 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 008MHZz 19 22 20 Carrier Detect Time Constant Part of the carrier detect integration function The value of C connected to this pin will affect the carrier detect response time and hence noise performance See Figure 2 Note 3 20 24 22 Vbo Positive supply rail A single 5 volt supply is required 4 6 17 4 No internal connection do not use Application Information XTAL CLOCK _y XTAL Tx SYNC O P Tx SIGNAL O P Tx DATA P Tx ENABLE BANDPASS O P Rx ENABLE
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CML Semiconductor FX469 1200/2400/4800 Baud FFSK Modem PRODUCT INFORMATION