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data bulletin cmx469a ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 1200/2400/4800bps msk modem preliminary information features applications selectable data rates 1200/2400/4800 bps full-duplex msk rx and tx bandpass filters clock recovery and carrier detect capabilities pin selected xtal/clock inputs 1.008mhz or 4.032mhz radio and general applications data-over-radio pmr/cellular signaling portable data terminals narrowband coax data channels two way radio (mpt1327) signaling personal/cordless telephone the cmx469a is a full-duplex pin-selectable 1200/2400/4800bps minimum shift key (msk) modem for fm radio links. the mark and space frequencies are 1200/1800, 1200/2400, and 2400/4800hz respectively. tone frequencies are phase continuous; transitions occur at the zero crossing point. the use of a common xtal oscillator with a choice of two clock frequencies (1.008mhz or 4.032mhz) provides data-rate, transmit frequencies, and rx/tx synchronization. the transmitter and receiver operate entirely independently including individual section powersave functions. the cmx469a includes on-chip circuitry for carrier detect and rx clock recovery, both of which are made available at output pins. rx, tx and carrier detect circuits contain bandpass filters to provide high quality signals to their respective paths. the carrier detect time constant is set by an external capacitor, which may be selected to optimize performance in high-noise environments. high sensitivity and good bit-error-rate performance can be achieved even under adverse signal conditions. the cmx469a operates with a 3.0v to 5.5v supply and is available in the following packages: 24-pin tssop (cmx469ae2), 20-pin soic (cmx469ad3), and 22-pin pdip (cmx469ap6).
1200/2400/4800bps msk modem 2 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. contents section page 1. block diagram................................................................................................................ 3 2. signal list.................................................................................................................. ..... 4 3. external components.................................................................................................... 6 4. general description....................................................................................................... 7 4.1 transmitter ................................................................................................................. ......... 7 4.2 receiver .................................................................................................................... .......... 7 5. application .................................................................................................................. ... 8 5.1 synchronous modem design considerations ..................................................................... 8 5.2 test set up................................................................................................................. ......... 9 5.3 bit error rate.............................................................................................................. ......... 9 6. performance specifications........................................................................................ 11 6.1 electrical specifications................................................................................................... .. 11 6.1.1 absolute maximum limits................................................................................................... ...... 11 6.1.2 operating limits .......................................................................................................... ............. 11 6.1.3 operating characteristics ................................................................................................. ........ 12 6.1.4 timing.................................................................................................................... ................... 14 6.2 packages.................................................................................................................... ....... 17 mx-com, inc. reserves the right to change specifications at any time without notice.
1200/2400/4800bps msk modem 3 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 1. block diagram figure 1: block diagram
1200/2400/4800bps msk modem 4 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 2. signal list pin no. signal e2 p6 d3 name type description 1 1 1 xtal/clock input the input to the on-chip inverter, for use with either a 1.008mhz or a 4.032mhz xtal or external clock. clock frequency selection is by the clock rate input pin. the selection of this frequency will affect the operational data rate of this device. refer to table 3. as specified in the performance specifications, this input signal should be actively clocked (either driven from an external source or via an xtal circuit). 222 xtal output output of the on-chip inverter. 3 3 3 tx sync out output a squarewave, produced on-chip, to synchronize the input of logic data and transmission of the msk signal. see figure 8 and section 4.1. 5 5 4 tx signal out output when the transmitter is enabled, this pin outputs the (140-step pseudo sinewave) msk signal. see figure 8. with the transmitter disabled, this output is set to a high-impedance state. 7 6 5 tx data in input serial logic data to be transmitted is input to this pin. 876 enable tx input a logic 0 will enable the transmitter. see figure 8. a logic 1 at this input will put the transmitter into powersave while forcing tx sync out to a logic 1 and tx signal out to a high-impedance state. this pin is internally pulled to v dd . 9 8 7 bandpass out output the output of the rx bandpass filter. this output impedance is typically 10k w and may require buffering prior to use. 10 9 8 rx enable input the control of the rx function. the control of other outputs is provided in table 2 11 10 9 v bias power the output of the on-chip analog bias circuitry. held internally at v dd /2, this pin should be bypassed to v ss by a capacitor (c2). see figure 2 and rx enable notes. this bias voltage is maintained under all powersave conditions. 12 11 10 v ss power negative supply (gnd). 13 12 11 unclocked data out output the recovered asynchronous serial data output from the receiver. 14 13 12 clocked data out output the recovered synchronous serial data output from the receiver. data is latched out by the recovered clock, available at the rx sync out. see figure 9 and figure 11. 15 14 13 carrier detect output when an msk signal is being received this output is a logic 1. 16 15 14 rx signal in input the msk signal input for the receiver. this input should be coupled via a capacitor, c3. 18 17 15 rx sync out output a flywheel squarewave output. this clock will synchronize to incoming rx msk data. see figure 9 and figure 11.
1200/2400/4800bps msk modem 5 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. pin no. signal e2 p6 d3 name type description 19 16 16 2400 / 1200 bps select input a logic 1 on this pin selects the 1200bps 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 2400bps option. tone frequencies are: one-half cycle of 1200hz represents a logic 1, one cycle of 2400hz represents a logic 0. this pin has an internal 1m w pull-up resistor. operational data rate configurations are illustrated in table 3. 20 18 17 4800 bps select input a logic '1' on this pin combined with a logic '0' on the 2400 / 1200 bps select pin will select the 4800 option (1m w pulldown resistor). tone frequencies are: one-half cycle of 2400hz represents a logic '1', one full cycle of 4800hz represents a logic '0'. this state can only be achieved using a 4.032mhz xtal input. operational data rate configurations are illustrated in table 3. 21 19 18 clock rate input 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). 22 20 19 carrier detect time constant bi-directional part of the carrier detect integration function. the value of c4 connected to this pin will affect the carrier detect response time and therefore the noise performance. 24 22 20 v dd power positive supply. a single 2.7 to 5.0 volt supply is required. this pin should be bypassed to v ss by a capacitor (c5). 4, 6, 17, 23 4, 21 no internal connection, do not use. table 1: signal list rx enable = rx function clock data output carrier detect rx sync out 1 = enabled enabled * enabled enabled 0 = powersave 0 1 or 0 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 stabilize and provide a valid output. table 2: rx enable control functions xtal/clock frequency 1.008mhz 4.032mhz clock rate pin 00111 2400 / 1200 select pin 10100 4800 select pin 00001 data rate (bps) 1200 2400 1200 2400 4800 table 3: operational data rate configuration
1200/2400/4800bps msk modem 6 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 3. external components figure 2: recommended external components for e2 package figure 3: recommended external components for d3 package component notes value component notes value r1 1.0m w c5 1.0f c1 33.0pf c6 1 1.0f c2 1 1.0f c7 33.0pf c3 0.1f x1 3, 4, 5 1.008mhz or 4.032mhz c4 2 0.1f table 4: recommended external components
1200/2400/4800bps msk modem 7 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. recommended external component notes: 1. v bias may be bypassed to v ss and v dd using c2 and c6 when input signals are referenced to the v bias pin. for input signals references to v ss , bypass v bias to v ss 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. 4. for best results, a crystal oscillator design should drive the clock inverter input with signal levels of at least 40% of v dd , peak to peak. tuning fork crystals generally cannot meet this requirement. to obtain crystal oscillator design assistance, consult your crystal manufacturer. 4. general description the cmx469a has two sections, apart from the xtal oscillator circuit and clock dividers. these sections may be independently powersaved. 4.1 transmitter the transmitter is enabled by taking enable tx low. serial data applied to tx data input is sampled internally and an msk sequence is generated. after filtering, this is output at tx signal out and the transmit clock derived from this signal is output at tx sync out. the tx data must be valid at the time of the rising edge of the tx sync clock signal. therefore, the optimum time to change tx data is on the falling edge of the tx sync clock. 4.2 receiver the receiver is enabled by taking rx enable high. the signal applied to rx signal in is filtered and recovered as serial data from the unclocked data out. a flywheel synchronizer is used to extract a clock from the recovered serial data stream. the clock is available at rx sync out and the retimed serial data is available at clocked data out. the optimum time to sample the clocked data out is on the falling edge of the rx sync out clock signal. 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 out. a bandpass output is also available from the output of the first rx filter stage, but will require buffering before use.
1200/2400/4800bps msk modem 8 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 5. application 5.1 synchronous modem design considerations the cmx469a is an easily applied data pump, which can be used with many protocols. because it is an msk, or minimum shift keying, modem, it achieves a more noise resistant, higher data rate in a narrower bandwidth than other fsk (frequency shift keying) modems. this characteristic is especially important for wireless applications because it fundamentally determines the bandwidth of rf transmissions which are strictly limited and controlled by regulatory agencies. using msk signaling, the cmx469a data modem can achieve a 2400bps data rate within the typical 300-3000 hz voice band of many common radios. in order to achieve this advantage, an msk modem must precisely control the bit rate and timing of the modulated tx output signal bits. this control is asserted by the msk modem with a data clock signal, which is output by the modem to pace the tx data source (e.g. a microcontroller). the data clock signal, in effect, indicates when the tx data source should provide the next tx data bit to the modem. see figure 4. because this type of interface involves the use of a modem generated bit clock signal to control the timing of when new tx data bits must be supplied from the data source, the interface is called synchronous. another characteristic of a synchronous modem is that, to receive data, it must first learn the data bit timing of the rx signal stream before it can accurately demodulate rx data bits. accordingly, a synchronous modem undergoes a period of training or synchronization when it first begins to receive a stream of msk modulated signal. during this initial receive phase, the received signal is evaluated over several bit times as the modem locks on and achieves proper receive synchronization. the training sequence, called a preamble, is a specific data pattern which must be added to the front of a transmit data stream with the start of each new transmission. a specific preamble data pattern (e.g. 16 bits of alternating 0,1,0,1 for the cmx469a) is used to optimize the training accuracy while minimizing the number of preamble bits required. tx data tx sync (data clock) data bit tx source (e.g. c) 0 11 give me bit 2 msk tx out msk modem transmitting i took bit 2 data: 0 1 1 give me bit 3 i took bit 3 give me bit 1 i took bit 1 figure 4: synchronous transmit operation non-synchronous or asynchronous interfaces are commonly found in wired applications, which do not have the bandwidth efficiency requirements of wireless systems. a well-known example is the serial port of a personal computer. the serial port of the personal computer can transmit a 1200bps (or faster) data signal over a single tx signal without using an additional data clock signal to control the precise rate and timing of data bits being transmitted to a typical telephone line data modem. popular modem standards such as bell 202 and v.23 use fsk signaling to pass such asynchronous serial port data signals over telephone systems. another aspect of asynchronous interfaces and modems is that they can carry data streams, which are not at the exact, nominal data rate. for example, a 1200bps fsk modem will typically operate properly when supplied with transmit data streams of 1201bps or 1199bps. because of the differences in synchronous and asynchronous interfaces, they cannot successfully operate if directly connected. in other words, a personal computers rs232 serial port cannot directly interface to an msk modem. this is because: the asynchronous interface may provide data bits too fast or too slow compared to the precise rate required for msk signaling (a bit rate, or pacing, incompatibility). the timing of each specific data bit presented by an asynchronous interface will not be aligned with the precise bit timing required for msk signaling (a bit timing incompatibility). synchronous and asynchronous interface can be successfully interfaced for applications requiring the advantages of both. this typically involves the use of data buffering and retiming circuits to resolve the timing and pacing issues.
1200/2400/4800bps msk modem 9 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 5.2 test set up error detector milli- ammeter true rms voltmeter true rms voltmeter carrier detect out high detector milli- ammeter oscilloscope buffer (interface) circuit dd v dd v tx data i/p tx sync tx signal o/p rx signal in rx sync clocked data out carrier detect out preamble & pseudo-random data generator telephone channel simulator (with attenuator and 5khz/8khz bw noise generator) cmx469a transmitter (components as fig. 2) cmx469a receiver (components as fig. 2) figure 5: cmx469a test set-up 5.3 bit error rate 150 200 300 500 700 800 input signal level (mv ) rms bit error rate 250 100 50 1x10 -5 1x10 -4 1x10 -3 1x10 -2 1x10 -1 10db snr * 12db snr * 20db snr * * bit rate bandwidth figure 6: typical variation of bit error rate with input level
1200/2400/4800bps msk modem 10 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. bit error rate (log scale) snr (db) bit rate bandwidth (lin scale) 0 10 -5 10 -4 2 4 6 8 10 -3 10 -2 2x10 -2 1 2 34 5 6 78 9 10 11 12 13 14 15 16 ideal coherent ffsk cmx469a figure 7: rx bit-error-rate vs. signal-to-noise ratio
1200/2400/4800bps msk modem 11 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6. performance specifications 6.1 electrical specifications 6.1.1 absolute maximum limits exceeding these maximum ratings can result in damage to the device. general notes min. max. units supply (v dd -v ss ) -0.3 7.0 v voltage on any pin to v ss -0.3 v dd + 0.3 v current v dd -30 30 ma v ss -30 30 ma any other pin -20 20 ma d3 / p6 packages total allowable power dissipation at t amb = 25 c 800 mw derating above 25 c 13 mw/ c above 25 c operating temperature -40 85 c storage temperature -55 125 c e2 packages total allowable power dissipation at t amb = 25 c 320 mw derating above 25 c 5.3 mw/ c above 25 c operating temperature -40 85 c storage temperature -55 125 c 6.1.2 operating limits correct operation of the device outside these limits is not implied. notes min. max. units supply (v dd -v ss )2.75.5v operating temperature -40 85 c xtal frequency 1 1.008 4.032 mhz operating limits notes 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.
1200/2400/4800bps msk modem 12 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6.1.3 operating characteristics for the following conditions unless otherwise specified. v dd = 2.7v @ t amb = 25 c and v dd = 3.0v to 5.5v at t amb = -40 c to 85 c xtal/clock frequency = 4.032mhz, bit rate = 1200 baud, rx input level = 300mv rms , notes min. typ. max. units static values i dd (v dd = 5.0v) rx enabled, tx disabled - 2 3.6 ma rx and tx enabled 2 4.5 ma rx and tx disabled 2 650 a i dd (v dd = 3.0v) rx enabled, tx disabled 2 1.5 ma rx and tx enabled 2 2.0 ma rx and tx disabled 2 300 a logic 1 level 1 70% v dd logic 0 level 1 30% v dd digital output impedance 4.0 k w analog and digital input impedance 100 k w tx output impedance (v dd = 5.0v) 0.6 1.0 k w dynamic values receiver signal input dynamic range snr = 50db 3, 4 100 230 1000 mv rms bit error rate at snr = 12db 4, 5 1200bps 2.5 10 -4 2400bps 1.5 10 -3 4800bps 1.5 10 -3 bit error rate at snr = 20db 4, 5 1200/2400/4800bps <1.0 10 -8 receiver synchronization at snr = 12db probability of bit 16 being correct 7 99.5 % carrier detect 3 sensitivity 1, 7, 8 150 mv rms probability of cd being high after bit 16: with snr = 12db 9 99.5 % with 230mvrms noise and no signal 9 5 %
1200/2400/4800bps msk modem 13 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. notes min. typ. max. units transmitter output tx output level 1 775 mv rms output level variation 1200/1800hz 0 1.0 db 1200/2400hz 0 1.0 db 2400/4800hz 0 1.0 db output distortion 10 3.0 5.0 % 3rd harmonic distortion 10 2.0 3.0 % isochronous distortion 1200hz - 1800hz/1800hz - 1200hz 25.0 40.0 m s 1200hz - 2400hz/2400hz - 1200hz 20.0 30.0 m s 2400hz - 4800hz/4800hz - 2400hz 10.0 20.0 m s logic 1 carrier frequency 1200bps 6 1200 hz 2400bps 6 1200 hz 4800bps 6 2400 hz logic 0 carrier frequency 1200bps 6 1800 hz 2400bps 6 2400 hz 4800bps 6 4800 hz operating characteristics 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 bit error rate with input level 4. snr = signal-to-noise ratio in the bit-rate-bandwidth. 5. see figure 7: rx bit-error-rate vs. signal-to-noise ratio 6. dependent upon xtal tolerance 7. with an alternating (1010) pattern. 8. measured with a 150mv rms input signal (no noise). 9. a signal level of 230mv rms is used in c.d. probability measurements. noise bandwidth is 5khz (1200/2400 baud operation) or 8khz (4800 baud operation). see section 3, note 2 for details on optimizing noise immunity. 10. for an unmodulated carrier
1200/2400/4800bps msk modem 14 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6.1.4 timing 6.1.4.1 1200bps characteristics note min. typ. max. unit tx enable to tx sync rise time t sync 416 s tx delay, signal to disable time t eset 2.0 800 s data set-up time t dset 12.0 s data hold time t dh 2.0 s tx delay to o/p time t txd 1.2 s tx data rate period t tdr 833 s rx data rate period t rdr 800 865 s undetermined state 2.0 s internal rx delay t id 1.5 ms notes: 1. consider the xtal/clock tolerance. 2. all tx timings are related to the tx sync output. tx enable tx sync tx data 1200 bps tx output open circuit open circuit dc = don't care dv = data valid dv dc dv dc dv dc dc t eset t txd t dset dset t dh t tdr t tdr t sync figure 8: transmitter timing: 1200bps rx signal i/p 1200 bps rx sync o/p (1200hz) clocked data o/p 1 1 0 0 logic '1' t id t rdr undetermined state logic '0' logic '1' logic '0' figure 9: receiver timing diagram: 1200bps
1200/2400/4800bps msk modem 15 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6.1.4.2 2400bps characteristics note min. typ. max. unit tx enable to tx sync rise time t sync 208 s tx delay, signal to disable time t eset 2.0 400 s data set-up time t dset 12.0 s data hold time t dh 2.0 s tx delay to o/p time t txd 1.2 s tx data rate period t tdr 416 s rx data rate period t rdr 400 433 s undetermined state 2.0 s internal rx delay t id 1.5 ms notes: 1. consider the xtal/clock tolerance. 2. all tx timings are related to the tx sync output. tx enable tx sync tx data 2400 bps tx output open circuit open circuit dc = don't care dv = data valid dv dv dc dv dv dc dc dv dv dc dc dc dc t eset t txd t dset dset t sync t dh t tdr t tdr figure 10: transmitter timing: 2400bps rx signal i/p 2400 bps rx sync o/p (2400hz) clocked data o/p 1 1 0 0 logic '1' logic '1' t id t rdr undetermined state logic '0' logic '0' logic '1' logic '1' logic '0' logic '0' figure 11: receiver timing: 2400bps
1200/2400/4800bps msk modem 16 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6.1.4.3 4800bps characteristics note min. typ. max. unit tx enable to tx sync rise time t sync 104 s tx delay, signal to disable time t eset 2.0 200 s data set-up time t dset 12.0 s data hold time t dh 2.0 s tx delay to o/p time t txd 1.2 s tx data rate period t tdr 208 s rx data rate period t rdr 200 216 s undetermined state 2.0 s internal rx delay t id 1.0 ms notes: 1. consider the xtal/clock tolerance. 2. all tx timings are related to the tx sync output. tx enable tx sync tx data 4800 bps tx output open circuit open circuit dc = don't care dv = data valid dv dv dc dv dv dc dc dv dv dc dc dc dc t eset t txd t dset dset t sync t dh t tdr t tdr figure 12: transmitter timing: 4800bps rx signal i/p 4800 bps rx sync o/p (4800hz) clocked data o/p 1 1 0 0 logic '1' logic '1' t id t rdr undetermined state logic '0' logic '0' logic '1' logic '1' logic '0' logic '0' figure 13: receiver timing: 4800bps
1200/2400/4800bps msk modem 17 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6.2 packages note : all dimensions in inches (mm.) angles are in degrees package tolerances a b c e e1 h typ. max. min. dim. j j1 k l 0.360 (9.14) 0.480 (12.19) 0.128 (3.25) 1.100 (27.94) 0.185 (4.70) 0.420 (10.67) 0.390 (9.91) 0.420 (10.67) 0.020 (0.51) 0.020 (0.51) 0.040 (1.02) 0.066 (1.68) 1.080 (27.43) 0.330 (8.38) 0.100 (2.54) 0.045 (1.14) 0.065 (1.65) 0.015 (0.38) p 0.010 (0.25) t y 7 e y e1 t c p j1 k h j l b a pin 1 figure 14: 22-pin pdip mechanical outline: order as part no. cmx469ap6 e l x t w pin 1 a b p j y alternative pin location marking h c k z note : all dimensions in inches (mm.) angles are in degrees package tolerances a b c e h typ. max. min. dim. j p x w t y k l 0.105 (2.67) 0.093 (2.36) 0.419 (10.64) 45 7 0 10 0.050 (1.27) 0.046 (1.17) 0.510 (12.95) 0.299 (7.59) 0.050 (1.27) 0.016 (0.41) 0.390 (9.90) 0.020 (0.51) 0.003 (0.08) 0.009 (0.23) 0.0125 (0.32) 0.013 (0.33) 0.020 (0.51) 0.036 (0.91) 0.495 (12.57) 0.286 (7.26) z 5 5 figure 15: 20-pin soic mechanical outline: order as part no. cmx469ad3
1200/2400/4800bps msk modem 18 cmx469a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480191.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. pin 1 a b alternative pin location marking e l t p j y c h 0.303 (7.70) package tolerances typ. max. min. a b c e h dim. j p y t l 0.047 (1.20) ---------- 0.256 (6.50) 0 8 0.030 (0.75) 0.311 (7.90) 0.177 (4.50) 0.0256 (0.65) 0.020 (0.50) 0.248 (6.30) 0.006 (0.15) 0.002 (0.05) 0.003 (0.08) 0.008 (0.20) 0.007 (0.17) 0.012 (0.30) 0.169 (4.30) note : all dimensions in inches (mm.) angles are in degrees figure 16: 24-pin tssop mechanical outline: order as part no. cmx469ae2

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