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data bulletin MX651 ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. telephone subscriber pulse metering & anti fraud tone processor preliminary information features applications rapid 18khz tone encoder-decoder can transfer nrz data tx up to 166bps rx up to 62bps 12khz subscriber pulse metering detector meets european 12khz spm frequency specifications payphone applications card operated telephone installations component adjustable input sensitivity low power 3.3v/5.0v operation clock oscillator and dividers sample & hold sample & hold filtering and frequency detection 12khz channel digital amplifier modulator band pass filter v bias xtal xtal ext clkin nrz data txout rx/tx ampout in in detect 12khz detect 18khz v ss v dd filtering and frequency detection 18khz channel the MX651 is a low power integrated circuit which combines 12khz subscriber pulse metering (spm) detection with 18khz tone processing for anti-fraud purposes within a telephone system. suitable for battery or line powered systems, the MX651 is protected from crosstalk and false decoding by employing high accuracy switched capacitor filters. by using simple logic or m processor control the MX651 will: decode 12khz spm pulses (in the presence of high level voice and 18khz signaling) and provide a logic output. transmit an nrz amplitude modulated 18khz security tone to line. decode an incoming modulated 18khz security tone (in the presence of high level voice and 12 khz spm tones) and provide a logic output. the MX651 is available in a 16-pin soic (MX651dw) and a 16-pin pdip (MX651p) package.
telephone spm and anti fraud tone processor 2 MX651 - preliminary information ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. contents section ........................................................................................................................ ....................... page 1. block diagram ............................................................................................................... ................... 3 2. signal list ................................................................................................................. ........................ 4 3. external components ......................................................................................................... ............. 5 4. general description ......................................................................................................... ................ 6 4.1 overall function ........................................................................................................... ............................. 6 4.1.1 spm (12khz) detector ..................................................................................................... ..................................6 4.1.2 security tone (18khz) detector (rx mode only) ............................................................................ ..................6 4.1.3 security tone transmission (tx mode only)................................................................................ .....................6 4.2 description of blocks (reference figure 1) ............................................................................... ............. 6 4.2.1 input amplifier .......................................................................................................... ..........................................6 4.2.2 sample and hold (12khz channel) .......................................................................................... .........................6 4.2.3 filtering and frequency detection (12khz channel) ........................................................................ .................6 4.2.4 sample and hold (18khz channel) .......................................................................................... .........................6 4.2.5 filtering and frequency detection (18khz channel) ........................................................................ .................6 4.2.6 clock oscillator and dividers ............................................................................................ .................................7 4.2.7 (gate on-off) (tx only) .................................................................................................. ................................7 4.2.8 band pass filter (tx only)............................................................................................... ..................................7 5. application ................................................................................................................. ...................... 7 5.1 device sensitivity versus v dd - input amplifier gain ................................................................................ 7 5.2 alias responses - false decodes ............................................................................................ ................ 7 5.2.1 12khz channel ............................................................................................................ ......................................7 5.2.2 18khz channel ............................................................................................................ ......................................8 6. performance specifications.................................................................................................. .......... 8 6.1 electrical performance ..................................................................................................... ......................... 8 6.2 system timing .............................................................................................................. ........................... 11 6.2.1 timing diagrams.......................................................................................................... .....................................11 6.3 packaging .................................................................................................................. .............................. 12 mx com, inc. reserves the right to change specifications at any time and without notice.
telephone spm and anti fraud tone processor 3 MX651 - preliminary information ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. 1. block diagram oscillator clock dividers 71.591khz 357.955khz 17.898khz 17.898khz modulated on/off level detector zero crossing detector sample and hold high pass filter 2 fc = 16khz 71.591khz frequency measurement enable frequency measurement enable band pass filter fc = 18khz gate 357.955khz v dd v ss v ss rx/tx posin negin ampout nrz data 3.579545mhz xtal clkin xtal xtal powersave 18khz channel powersave tx circuitry 18khz channel 12khz channel 17.898khz sample and hold high pass filter 1 fc = 5khz level detector zero crossing detector 17.898khz digital amplitude modulator v bias txout (18khz ask signal) detect 18khz v dd r1 r3 r5 r4 c4 c3 c1 c2 c5 r2 v ss detect 12khz figure 1: block diagram
telephone spm and anti fraud tone processor 4 MX651 - preliminary information ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. 2. signal list pin no. signal type description 1 xtal input input to the on-chip oscillator inverter. 2 xtal output inverted output of the on-chip oscillator. 4 clkin input a logic input which may be used when an external clock signal is available in place of a crystal. the external 3.579545mhz signal is applied to this pin and xtal is tied to v dd . when not used, this pin should be tied to v dd . 5 rx / tx input a logic input which controls the operating mode of the device. in rx, the device detects the presence of 12khz and 18khz tones. in tx, the18khz detect function is disabled and 18khz is transmitted from the txout pin modulated on -off by the nrz data pin. 6 nrz data input a logic input used in tx mode to ask modulate the txout pin. a logic high corresponds to no tone and logic low corresponds to 18khz. 7 txout output the tx mode output. it is ask modulated by the nrz data input pin. it transmits 18khz or no tone depending upon the state of the nrz data input pin. this pin goes to a high impedance state when in rx mode. 8v ss power negative supply. 9v bias output a bias line for the internal circuitry, held at v dd /2 it also forms the analog ground for the input differential amplifier. this pin must be bypassed by a capacitor mounted close to the device pins (see figure 1). 10 ampout output output of the input amplifier. external components are used in conjunction with the amplifier to couple the line signal into the device. both inputs are available to allow a differential configuration because a two wire input is assumed. 11 negin input inverting input to the input amplifier. 12 posin input non-inverting input to the input amplifier. 13 detect 18khz output logic output of the 18khz channel. logic 0 when a 18khz tone (within specified frequency and amplitude limits) has been detected for a minimum length of time. 14 detect 12khz output logic output of the 12khz channel. logic 0 when a 12khz tone (within specified frequency and amplitude limits) has been detected for a minimum length of time. 16 v dd power positive supply. levels and voltages are dependent upon this supply. this pin should be bypassed to v ss by a capacitor (see figure 1). 3, 15 n/c no internal connection: leave open circuit.
telephone spm and anti fraud tone processor 5 MX651 - preliminary information ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. 3. external components 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 xtal xtal v dd v dd v ss v bias rx/tx txout r5 c5 nrz data n/c clkin n/c c4 c1 r3 r2 r1 r4 c2 c3 detect12 detect18 posin negin ampout MX651 r1, r3 see note 1 1.1m w @ 3.3v 1% 1.0m w @ 5.0v 1% r2, r4 see note 1 270k w @ 3.3v 1% 330k w @ 5.0v 1% c1, c2 see note 1 33pf @ 3.3v 10% 68pf @ 5.0v 10% c3, c4 0.1f 20% r5 51k w 1% c5 100pf 10% xtal see note 2 3.579545mhz figure 2: recommended external components external components notes 1. the device sensitivity is proportional to the power supply (v dd ) voltage. the input gain must compensate for this and also prevent input circuitry saturation. it is recommended that amplifier components (r1 to r4, c1 and c2) be used to set the gain between -10db (if v dd is 5.0v) and -13db (if v dd is 3.3v). 2. 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 type crystals generally cannot meet this requirement. to obtain crystal oscillator design assistance, consult your crystal manufacturer
telephone spm and anti fraud tone processor 6 MX651 - preliminary information ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. 4. general description 4.1 overall function the MX651 is a dual channel tone detector for use in european, french, and other payphone systems where 12khz spm and 18khz security tones are used. 4.1.1 spm (12khz) detector the spm detector channel responds to a low level (50mv) 12khz tone in the presence of a large security tone (16khz - 20khz) and speech. the device responds after a period of continuous valid tone and so recognizes a valid spm toneburst (minimum transmission duration, 40 - 50ms). this function is permanently enabled. 4.1.2 security tone (18khz) detector (rx mode only) this demodulates the 18khz ask signal in the presence of the spm signaling. 4.1.3 security tone transmission (tx mode only) an 18khz tone modulated on - off by the nrz data pin. a logic 0 gates the signal on so that 18khz is transmitted. a logic 1 gates the signal off so that no tone appears at the txout pin. 4.2 description of blocks (reference figure 1) 4.2.1 input amplifier this input amplifier is connected as a differential amplifier and is used to couple the signal into the device. it also attenuates the combined speech, spm tone and security tone to prevent its output saturating. the signal gain should be - 10db at 5.0v supply and -13db at 3.3v. (see figure 2 for recommended component values). 4.2.2 sample and hold (12khz channel) this samples the input signal at 17.898khz and creates images of the incoming frequencies. the 12khz spm is translated to 5.898khz and the security tone is translated to between 978hz and 1182hz. this simplifies the subsequent signal processing. 4.2.3 filtering and frequency detection (12khz channel) the output of the sample and hold circuit is passed to filter hpf1. this is a switched capacitor high pass filter which amplifies the frequency shifted spm tone (about 5.9khz) but rejects the frequency shifted security tone (about 1khz). the filter also rejects any speech signals present. the filter output is passed to the level detect and frequency measurement circuitry which determines the presence or absence of a valid spm signal on the line. a valid signal sends the "detect 12khz" pin to logic low. 4.2.4 sample and hold (18khz channel) this samples the input signal at 71.592khz. it is synchronized with the following high pass filter, which is a switched capacitor circuit with the same sampling rate. the sample and hold circuit stores the value of the input waveform value between sampling instants so that it is a suitable input for the filter. without the sample and hold circuit, speech or spm tone components which are large compared with the security tone would interfere with the level discrimination at the filter output. 4.2.5 filtering and frequency detection (18khz channel) the output of the sample and hold circuit is passed to filter hpf2. this is a switched capacitor high pass filter which amplifies the security tone (about 16.92khz - 19.08khz) but rejects the spm tone. the filter output signal is passed to the level detect and frequency measurement circuitry which determines the presence or absence of a valid security tone on the line. a valid signal sends the "detect 18khz" pin to logic 0.
telephone spm and anti fraud tone processor 7 MX651 - preliminary information ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. 4.2.6 clock oscillator and dividers these circuits generate the internal clocks by division of the oscillator reference frequency. the crystal is connected as shown in figure 2 without any need for other external components. when a crystal is used, the clkin pin should be left open circuit. alternatively, when a frequency of 3.579545mhz is externally available, the use of a crystal is unnecessary. the external frequency is applied to the clkin pin. in this case, the xtal pin should be tied to v dd . in tx, the dividers also generate a pulse train, frequency 18khz, which is passed to the tx circuitry (gate on - off and band pass filter) for digital modulation and filtering. 4.2.7 (gate on-off) (tx only) this circuit is a digital block. it performs on - off modulation of the 18khz pulse train generated from the crystal frequency by the digital dividers. it is controlled by the nrz data pin and is used to encode nrz data packets as pulsed 18khz (ask data). the modulated digital signal is passed to the tx filter for wave shaping. 4.2.8 band pass filter (tx only) this is a 4th order band pass filter with center frequency 18khz. it shapes the modulated digital pulse train from the previous block into a low distortion pulsed sinusoidal waveform. the resulting signal is the system acknowledgment security tone. it is transmitted by the subscriber equipment, via the telephone link, to the local exchange. 5. application 5.1 device sensitivity versus v dd - input amplifier gain the device sensitivity is proportional to v dd because internal voltage references are derived from the power supply. accordingly, input amplifier signal gain should be adjusted via external components. figure 2 shows components recommended for 5.0v and 3.3v operation. 5.2 alias responses - false decodes the MX651 is designed to work in telephone systems where certain ranges of input frequencies are expected and other ranges are not. the 12khz spm channel works in the presence of speech and a tone in the range 16khz - 20khz. the security tone detector functions in the presence of an interfering tone in the range 11khz - 13khz. a significant tone at other frequencies may interfere with correct decoding of valid transmissions and should be avoided. a small range of input frequencies could cause false decoding when no valid tone has been received. this is because of the frequency shifting property of the spm channel and the sampled data filters in both channels. the tone detectors in both the 12khz and 18khz channels will respond to other than normal tones. accordingly, such tones should be avoided. 5.2.1 12khz channel the 12khz tone detector response frequencies are described by the following two equations: f 12khz plus = [(n x 17.898khz) + 5.893khz] 0.185khz f 12khz minus = [(n x 17.898khz) - 5.893khz] 0.185khz n nominal plus detect frequency (khz) nominal minus detect frequency (khz) 0 5.893 n/a 1 23.791 12.005 2 41.689 29.903 sign
telephone spm and anti fraud tone processor 8 MX651 - preliminary information ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. note: a valid spm input, in the range 11.82khz - 12.18khz, is met when; n = 1 and the nominal minus sign (-) detect frequency is calculated. the other inputs represent false decodes. the response time and level sensitivity for a false decode is the same as that for a valid decode, e.g. 42ms - 45ms of 5708hz at 50mv could cause a false decode at the "detect 12khz" pin. 5.2.2 18khz channel the 18khz tone detector response frequencies are described by the following two equations: f 18khz plus = [(n x 71.591khz) + 18.0khz] 1.08khz f 18khz minus = [(n x 71.591khz) - 18.0khz] 1.08khz n nominal plus detect frequency (khz) nominal minus detect frequency (khz) 0 18 n/a 1 89.591 53.591 2 161.182 125.182 3 232.773 196.773 note: a valid security tone input is met when, n = 0 and the nominal plus sign (+) detect frequency is calculated. the other inputs represent false decodes. the response time and level sensitivity for a false decode is the same as that for a valid decode, e.g. 5.8ms of 52.511khz at 40mv could cause a false response at detect18khz pin. 6. performance specifications 6.1 electrical performance absolute maximum ratings exceeding these maximum ratings can result in damage to the device. correct operation of the device outside these limits is not implied. general min. max. units supply (v dd - v ss ) -0.3 7.0 v voltage on any pin (wrt v ss ) -0.3 v dd + 0.3 v current v dd -30 30 ma v ss -30 30 ma any other pins -20 20 ma dw / p packages total allowable power dissipation at t amb = 25c 800 mw derating above 25c 13 mw/c above 25c operating temperature -40 85 c storage temperature -55 125 c sign
telephone spm and anti fraud tone processor 9 MX651 - preliminary information ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. operating limits for the following conditions unless otherwise specified. min. max. units supply (v dd - v ss ) 3.0 5.5 v operating temperature -40 85 c xtal frequency 3.579008 3.580082 mhz operating characteristics for the following conditions unless otherwise specified: xtal frequency = 3.579545mhz, noise and distortion measured in 50khz bandwidth v dd = 3.3v to 5.5v @ t amb = 25c. notes min. typ. max. units dc parameters i dd 1 2.5 4.0 ma i dd 2 1.0 2.0 ma logic 1 input level 1, 3 3.5 v logic 0 input level 1, 3 1.5 v logic 1 output level at i oh = -120 m a 1 4.6 v logic 1 output level at i ol = 360 m a 1 0.4 v ac parameters tx output tx output impedance (tx mode) 4 1.0 2.5 k w tx output impedance (rx mode) 4 300 500 k w output frequency 17.82 18.18 khz output distortion 5 2 % signal level 5, 6 3.0 3.4 3.7 v p-p signal level 5, 7 2.0 2.2 2.4 v p-p response/de-response times 8 100 s rise/fall times 9 5 ms rx input 10 rx input impedance 10.0 m w rx input amp voltage gain 500 v/v 12khz (spm) channel performance 11 with interfering speech & security tone 12 input signal level 12 800 mv decode min signal level 12 50 mv no decode max signal level 12 25 mv response delay 12, 13 40 50 ms de-response delay 12, 13 40 50 ms detect bandwidth 12 11.82 12.18 khz not detect frequencies (below 12khz) 12 11.52 khz not detect frequencies (above 12khz) 12 12.48 khz
telephone spm and anti fraud tone processor 10 MX651 - preliminary information ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. notes min. typ. max. units 18khz (security tone) channel performance 14 with interfering speech & spm tone 15 input signal level 15 1.2 v decode min signal level 15 40 mv no decode max signal level 15 10 mv response/de-response times 15, 16 8 ms detect bandwidth 15 16.92 19.08 khz not detect frequencies (below 18khz) 15 16.25 khz not detect frequencies (above 18khz) 15 19.75 khz operating characteristics notes: 1. at v dd = 5.0v only, i dd specification does not include any current drawn from the device pins by external circuitry. 2. at v dd = 3.3v only, i dd specification does not include any current drawn from the device pins by external circuitry. 3. clkin input signal may be sinusoidal. 4. small signal impedance. 5. at output of smoothing network. 6. v dd = 5.0v. 7. v dd = 3.3v. 8. the time between a logic 1 - 0 transition at nrz data input and the tone amplitude at txout reaching 10% of its full value or between a 0 - 1 transition at nrz data input and the tone amplitude falling to 90% of its full value. 9. the time for the 18khz tone amplitude at txout to rise from 10% to 90% or to fall from 90% to 10% of its full value. 10. input amplifier signal gain set to -10db for v dd = 5.0v, -13db for v dd = 3.3v. 11. maximum 10% distortion for incoming spm tone, not including interfering speech or security tone (16khz - 20khz). minimum snr 22db for incoming spm tone before the input capacitor. 12. signal levels at the amplifier input, i.e. before the input capacitor. 12khz channel performance specified in the presence of the following interfering signals: (a) a 1.2v continuous tone in the frequency range 16khz - 20khz (b) an ordinary speech signal containing frequencies in the range 300hz - 3400hz of maximum instantaneous amplitude 8.0v p-p 13. the device responds after 40-50ms of continuous valid tone and de-responds after: a 40-50ms period of no-tone, tones less than 25mv or an out of band tone. 14. maximum 10% distortion for incoming security tone, not including interfering spm tone (11khz - 13khz). minimum 20db snr for incoming security tone. 15. signal level specified at the amplifier input, i.e. before the input capacitor. performance specified in the presence of an interfering 800mv continuous tone in the frequency range 11khz - 13khz. 16. the device responds after 8ms of continuous valid tone and de-responds after any of: an 8ms period of no-tone, tone of 10mv or less, or an out of band tone.
telephone spm and anti fraud tone processor 11 MX651 - preliminary information ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. 6.2 system timing notes min max unit rx 12khz response delay 40 50 ms de-response delay 40 50 ms 18khz response time 8 ms de-response time 8 ms tx transmit 0 time note 1, 2 5.1 ms transmit 1 time note 1, 2 5.1 ms note: 1. tx transmit times include both response/de-response times and rise/fall times. 2. the tx transmit 0 and transmit 1 time must exceed 5.1ms. 6.2.1 timing diagrams 12khz tone bursts "detect 12khz" pin deresponse delay response delay figure 3: spm (12khz) channel. toneburst and tonegaps < the response and de-response delays are ignored 18khz tone bursts "detect 18khz" pin deresponse time response time figure 4: security tone (18khz) channel. the response and de-response times are short to enable the device to recognize short on-off bursts (20ms each)
telephone spm and anti fraud tone processor 12 MX651 - preliminary information ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. rx / pin tx txout don't care don't care transmit 1 time transmit 0 time transmit 0 time high z high z nrz data figure 5: transmit mode. txout is modulated by the nrz data pin. an 18khz toneburst represents logic 0 and "no tone" represents logic 1. data packets with symbol periods 3 6ms can be transmitted. 6.3 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 6: soic mechanical outline: order as part no. MX651dw
telephone spm and anti fraud tone processor 13 MX651 - preliminary information ? 1997 mx com inc. www.mxcom.com tele: 800 638-5577 910 744-5050 fax: 910 744-5054 doc. # 20480137.003 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective companies. 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 7: pdip mechanical outline: order as part no. MX651p

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