data bulletin MX128 *electronics communications privacy act (title 18, us code 2510 et seq.) ?1998 mx-com inc. www. mxcom.com tel: 800 638-5577 336 744-5050 fax: 336 744-5054 doc. # 20480101.010 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective comp anies. cordless telephone scrambler features applications full-duplex audio processing on-chip filters carrier rejection >55db uses if (10.24 mhz) clock requires no extra crystal excellent audio quality low voltage 3.3v/5.0v operation ecpa* qualified voice protection battery powered portability cordless telephones wireless pbxs - + - + rx path tx path v v bias bias inversion carrier the MX128 is a full-duplex frequency inversion scrambler designed to provide secure conversations for 46/49 mhz cordless telephone users. the rx and tx audio paths consist of the following: 1. a switched-capacitor balanced modulator with high baseband and carrier rejection. 2. a 3.3 khz inversion carrier (injection tone). 3. a 3100 hz lowpass filter. 4. input op-amps with externally adjustable gain. the MX128 uses mixed signal cmos switched-capacitor filter technology and operates from a single supply in the range of 3.0v to 5.5v. the inversion carrier's frequency and filter switching clock are generated on-chip using an external 10.24 mhz or 3.58/3.6864 mhz crystal or clock input (selectable). the MX128 is available in the following package styles: 16-pin soic (MX128dw) and 16-pin pdip (MX128p).
cordless telephone scrambler 2 MX128 ?1998 mx-com inc. www. mxcom.com tel: 800 638-5577 336 744-5050 fax: 336 744-5054 doc. # 20480101.010 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective comp anies. contents section page 1. block diagram .......................................................................................................... 3 2. signal list ................................................................................................................. 4 3. external components .............................................................................................. 5 4. application ................................................................................................................ 6 4.1 application notes........................................................................................................... ......... 6 5. performance specification ...................................................................................... 7 5.1 electrical performance ...................................................................................................... ..... 7 5.2 packaging................................................................................................................... .......... 10 mx?com, inc. reserves the right to change specifications at any time and without notice.
cordless telephone scrambler 3 MX128 ?1998 mx-com inc. www. mxcom.com tel: 800 638-5577 336 744-5050 fax: 336 744-5054 doc. # 20480101.010 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective comp anies. 1. block diagram - + - + clocks and logic rx gain amp out rxin 12 11 2 1 15 14 6 5 4 8 9 16 13 v bias v dd v/2 dd v ss xtal/clock clr 10.24/3.58 mhz clock select xtal txin tx gain amp out rx channel tx channel 212 khz 3.3 khz rxout txout 0v v bias v bias figure 1: device block diagram
cordless telephone scrambler 4 MX128 ?1998 mx-com inc. www. mxcom.com tel: 800 638-5577 336 744-5050 fax: 336 744-5054 doc. # 20480101.010 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective comp anies. 2. signal list pin no. signal type description 1 xtal output this is the output of the clock oscillator inverter 2 xtal/clock input a 10.24 mhz, 3.58/3.6864 mhz, or an externally derived clock signal is injected at this pin. see figure 3 4 txout output this is the analog output of the transmit channel. it is internally biased at v dd /2 5 tx gain ampout output this is the output pin of the transmit channel gain adjusting op- amp. see figure 4 for gain setting components 6 txin input this is the analog signal input to the transmit channel. this input is to a gain adjusting op-amp whose gain is set by internal components. see figure 4. 8v ss power negative supply (gnd) 9v bias output this is an internally generated bias voltage output (v dd /2) 11 rxin input this is the analog signal input to the receive channel. this input is to a gain adjusting op-amp whose gain is set by internal components. see figure 4. 12 rx gain ampout output this is the output pin of the receive channel gain adjusting op- amp. see figure 4 for gain setting components 13 rxout output this is the analog output of the receive channel. it is internally biased at v dd /2 14 clr a logic 1 on this input selects the invert mode. a logic 0 selects the clear (not inverted) mode 15 clock select selects either 10.24 or 3.58/3.6864 mhz clock frequency. a logic 1 selects 10.24 mhz, and a logic 0 selects 3.58/3.6864 mhz. this input is internally pulled high 16 v dd power positive supply of 3.0v to 5.5 v 3, 7, 10 n/c no internal connections
cordless telephone scrambler 5 MX128 ?1998 mx-com inc. www. mxcom.com tel: 800 638-5577 336 744-5050 fax: 336 744-5054 doc. # 20480101.010 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective comp anies. 3. external components MX128 inset see inset below see inset below 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 16 15 14 13 12 11 10 9 xtal xtal/clock n/c txout tx gain amp out txin n/c xtal xtal/clock n/c txout tx gain amp out txin n/c r x c c c ss 1 1 2 3 1 dd bias v dd v clk sel clr rxout rx gain amp out rxin n/c v v clk sel clr rxout rx gain amp out rxin n/c v xtal/clock xtal 1 2 MX128 see fig. 4 see fig. 4 see fig. 4 see fig. 4 } } v 10.24 mhz 3.58/3.6864 mhz r1 1.0m 10% r1 1.0m 10% c1 0.47f 20% c1 0.47f 20% c2 22.0pf 20% c2 33.0pf 20% c3 22.0pf 20% c3 47.0pf 20% x1 10.24 mhz x1 note 1 3.58/3.6864 mhz figure 2: recommended external components external components note: 1. for best results, a crystal oscillator should drive the clock inverter input with signal levels of at least 40% of v dd peak - peak. tuning fork crystals generally cannot meet this requirement. to obtain crystal oscillator design assistance, consult your crystal manufacturer.
cordless telephone scrambler 6 MX128 ?1998 mx-com inc. www. mxcom.com tel: 800 638-5577 336 744-5050 fax: 336 744-5054 doc. # 20480101.010 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective comp anies. 4. application 12 120pf 100k 100k 100k 100k 100k 100k rxin rxout 11 13 .1uf .1uf 150pf 150pf 150pf 150pf 5 120pf 100k 100k txin txout 6 4 .1uf .1uf rf amp rf amp af amp af amp hybrid transformer telephone line de-emp pre- emp code detect code encode modulator fm detector if amp p m base 12 120pf 100k 100k rxin rxout 11 13 .1uf .1uf 5 120pf 100k 100k txin txout 6 4 .1uf .1uf rf amp rf amp af amp mic. af amp spkr de-emp pre- emp code detect code encode modulator keypad fm detector if amp dtmf generation p portable MX128 MX128 note: components shown set a gain of 0db. figure 3: block diagram of a typical application of the MX128 (cordless phone) 4.1 application notes formulas for calculating the carrier frequency, upper cutoff frequency and lower cutoff frequency with clock select pin high are as follows: carrier frequency = (3.2995khz / 10.24mhz) * xtal frequency upper cutoff frequency = (2.800khz / 10.24mhz) * xtal frequency lower cutoff frequency = (400hz / 10.24mhz) * xtal frequency formulas for calculating the carrier frequency, upper cutoff frequency and lower cutoff frequency with clock select pin low are as follows: carrier frequency = (3.2995khz / 3.415mhz) * xtal frequency upper cutoff frequency = (2.800khz / 3.415mhz) * xtal frequency lower cutoff frequency = (400hz / 3.415mhz) * xtal frequency
cordless telephone scrambler 7 MX128 ?1998 mx-com inc. www. mxcom.com tel: 800 638-5577 336 744-5050 fax: 336 744-5054 doc. # 20480101.010 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective comp anies. 5. performance specification 5.1 electrical performance absolute maximum ratings exceeding these maximum ratings can result in damage to the device. general min. max. units supply voltage (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 p/dw packages total allowable power dissipation at t amb = 25c 800 mw max. derating above 25c 10 mw/c above 25c operating temperature -40 85 c storage temperature -55 125 c operating limits correct operation of the device outside these limits is not implied. notes min. max. units supply (v dd - v ss )3.05.5v operating temperature -40 85 c clock frequency 10.24 mhz
cordless telephone scrambler 8 MX128 ?1998 mx-com inc. www. mxcom.com tel: 800 638-5577 336 744-5050 fax: 336 744-5054 doc. # 20480101.010 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective comp anies. operating characteristics for the following conditions unless otherwise specified: v dd = 3.3v at t amb = 25c clock frequency = 10.24mhz audio level 0db ref. @ 1khz = (v dd -1) x 150mv rms e.g. v dd = 3.3v 0db = 345mv rms. notes min. typ. max units static values supply current 2.0 3.0 ma input impedance digital 2 100 k amplifiers 2 1.0 10.0 m output impedance (rxout, txout) 1.0 k input logic 1 voltage 1 70% v dd input logic 0 voltage 1 30% v dd dynamic values analog signal input levels -16.0 3 db analog output noise 4 2.5 5.0 mv rms clear mode passband -3db cutoff frequencies low 300 hz high 3000 hz passband ripple (300-3000hz) rx channel 0 3.6 db tx channel 0 2.9 db passband ripple (500-2750hz) rx channel 0 2.2 db tx channel 0 2.0 db filter attenuation at 3.3 khz rx channel 30 db tx channel 30 db filter attenuation at 3.6 khz rx channel 45 db tx channel 45 db passband gain (@1khz ref.) rx channel -1.5 0.5 db tx channel -1.5 0.5 db switched-capacitor filter sampling 211.066 khz carrier frequency 3298 hz invert mode combined tx and rx response passband -3db cutoff frequencies low 400 hz high 2800 hz passband gain -3 0.5 db distortion (@1khz) 3 1.75 2.75 % passband gain (@1khz ref.) 5 -2.5 -1.5 0 db low frequency roll-off (<200 hz) 12 db/octave
cordless telephone scrambler 9 MX128 ?1998 mx-com inc. www. mxcom.com tel: 800 638-5577 336 744-5050 fax: 336 744-5054 doc. # 20480101.010 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective comp anies. notes min. typ. max units invert mode single channel response unwanted modulation products 3 rx channel -40 db tx channel -40 db carrier breakthrough 3 rx channel -55 db tx channel -55 db baseband breakthrough 3 rx channel -40 db tx channel -40 db operating characteristics notes: 1. batch sampled only 2. by characterization only 3. measured with input level 0db 4. short circuit rx or tx input, measure noise at corresponding analog output, in 30khz bandwidth 5. op amp gain 0db 6. clear mode only
cordless telephone scrambler 10 MX128 ?1998 mx-com inc. www. mxcom.com tel: 800 638-5577 336 744-5050 fax: 336 744-5054 doc. # 20480101.010 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective comp anies. 5.2 packaging pin 1 a b alternative pin location marking x p j y c k h e l t w 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) 0.041 (1.04) 0.413 (10.49) 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) 0.395 (10.03) 0.286 (7.26) z 5 5 figure 4: 16-pin soic mechanical outline: order as part no. MX128dw package tolerances note : all dimensions in inches (mm.) angles are in degrees typ. max. min. a b c e e1 h dim. j j1 p y t k l 0.200 (5.06) 0.262 (6.63) 0.390 (9.91). 7 0.150 (3.81) 0.810 (20.57) 0.135 (3.43) 0.100 (2.54) 0.121 (3.07) 0.300 (7.62) 0.290 (7.37) 0.325 (8.26) 0.015 (0.38) 0.070 (1.77) 0.008 (0.20) 0.015 (0.38) 0.014 (0.35) 0.023 (0.58) 0.040 (1.02) 0.065 (1.65) 0.056 (1.42) 0.064 (1.63) 0.740 (18.80) 0.240 (6.10) b a pin 1 e y e1 t k h j1 j c p l figure 5: 16-pin pdip mechanical outline: order as part no. MX128p
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