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CMX612 calling line identifier with vmwi ? 2002 consumer microcircuits limited d/612/3 february 2002 advance information features applications cli, cidcw and vmwi system operation cli and cidcw adjunct boxes class (fsk) and sdt (stuttered dial tone) cli and cidcw feature phones low power operation 0.5ma at 2.7v computer telephone integration zero - po wer detector for ring or line reversal low cas tone falsing in cidcw mode call logging systems voice - mail equipment bellcore, etsi, bt and mercury compatible 1.1 brief description the CMX612 is a low power cmos integrated circuit for the reception of physical layer signals used in british telecom?s ca lling line identification service (clip), bellcore?s calling identity delivery system (cid), the cable communications association?s caller display services (cds) and similar evolving systems. it also meets the requirements of emerging caller identity with call waiting services (cidcw). in addition, it provides visual message waiting indicator (vmwi) detection in both class (fsk) and (sdt) stuttered dial tone modes. two different signal inputs are provided to the device, to support tip/ring and hybrid conne ctivity. the device includes a ?zero - power? ring or line reversal detector, a dual - tone (2130hz plus 2750hz) tone alert signal detector, a dual - tone (350hz plus 440hz) stuttered dial tone detector and a 1200 - baud fsk v23/bell202 compatible asynchronous dat a demodulator with a data retiming circuit which removes the need for a uart in the associated m controller. it is suitable for use in systems to bt specifications sin227 and sin242, bellcore gr - 30 - core and sr - tsv - 002476, cca tw/p&e/312, etsi ets 300 659 p arts 1 and 2, ets 300 778 parts 1 and 2 and mercury communications mnr 19.
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 2 d/612/3 contents section page 1.0 features and applications ................................ .......................... 1 1.1 brief description ................................ ................................ ............ 1 1.2 block diagram ................................ ................................ ................. 3 1.3 signal list ................................ ................................ ......................... 4 1.4 external components ................................ ................................ ... 6 1.5 general description ................................ ................................ ...... 7 1.5.1 mode control logic ................................ ................................ 7 1.5.2 input signal amplifier ................................ ............................. 7 1.5.3 bandpass filter ................................ ................................ ....... 8 1.5.4 level detector ................................ ................................ ......... 8 1.5.5 fsk demodulator ................................ ................................ .... 9 1.5.6 fsk data retiming ................................ ................................ .. 9 1.5.7 tone alert de tector ................................ ............................... 10 1.5.8 dial tone detector ................................ ................................ 11 1.5.9 ring or line polarity reversal detector .............................. 12 1.5.10 xtal osc and clock dividers ................................ ................. 13 1.6 application not es ................................ ................................ ........ 14 1.6.1 'on - hook' operation ................................ ............................. 14 1.6.2 'off - hook' operation ................................ ............................. 17 1.6.3 vmwi operation ................................ ................................ .... 19 1.7 performance specification ................................ ....................... 21 1.7.1 electrical performance ................................ .......................... 21 1.7.2 packaging ................................ ................................ .............. 26 note: this product is in development: changes and additions will be made to this specification. items marked tbd or left blank will be incl uded in later issues. information in this data sheet should not be relied upon for final product design.
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 3 d/612/3 1.2 block diagram figure 1 : block diagram
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 4 d/612/3 1.3 signal list package e3 package p6 signal description pin no. pin no. name type 1 1 xtaln o/p the output of the on - chip xtal oscillator inverter. 2 2 xtal i/p the input to the on - chip xtal oscillator inverter. 3 3 rd i/p(s) input to the ring or line polarity reversa l detector. 4 4 rt bi open - drain output and schmitt trigger input forming part of the ring or line polarity reversal detector. an external resistor to v dd and a capacitor to v ss should be connected to rt to filter and extend the rd input signal. 5 5 inpu t select i/p(s) controls the selection of the two input signal amplifiers. a low level selects input 1 and a high level selects input 2. 6 6 aop1 bi the output of on - chip input signal amplifier 1 and an input to the signal selection multiplexer. 7 7 in v1 i/p the inverting input to on - chip input signal amplifier 1. 8 8 ninv1 i/p the non - inverting input to on - chip input signal amplifier 1. 9 10 v bias o/p internally generated bias voltage, held at ? v dd when the device is not in ?zero - power? mode. should be decoupled to v ss by a capacitor mounted close to the device pins. 10 11 v ss power negative supply rail (signal ground). 11 12 ninv2 i/p the non - inverting input to on - chip input signal amplifier 2. 12 13 inv2 i/p the inverting input to on - chip input signal amplifier 2. 13 14 aop2 bi the output of on - chip input signal amplifier 2 and an input to the signal selection multiplexer. 14 15 mode 2 i/p(s) input used to select the operating mode. see section 1.5.1. 15 16 mode 1 i/p(s) as per mode 2 descript ion.
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 5 d/612/3 package e3 package p6 signal description pin no. pin no. name type 16 17 irqn o/p an open - drain active low output that may be used as an interrupt request/wake - up input to the associated m c. an external pull - up resistor should be connected between this output and v dd . 17 18 det o/p a logic level output driven by the ring or line polarity reversal detector, the tone alert detector, the dial tone detector or the fsk level detect circuits, d epending on the operating mode. see section 1.5.1. 18 19 rxck i/p(s) an input which may be used to clock received data bits out of the fsk data retiming block. 19 21 rxd o/p a logic level output carrying either the raw output of the fsk demodulator or re - timed 8 - bit characters depending on the state of the rxck input. see section 1.5.6. 20 22 v dd p ower the positive supply rail. levels and thresholds within the device are proportional to this voltage. should be decoupled to v ss by a capacitor mounted clo se to the device pins. 9, 20 not used. do not connect to these pins. notes: i/p = input i/p(s) = schmitt trigger input o/p = output bi = bidirectional
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 6 d/612/3 1.4 external components r1 470k w c1, c2 18pf r2 see section 1.5.8 c3, c4 0.1 m f r3, r4, r5 470k w c5 0.33 m f r6, r7 470k w c6, c7 680pf r8 470k w for v dd = 3.3v c8, c9 0.1 m f r9 680k w for v dd = 5.0v (see section 1.5.2) 240k w for v dd = 3.3v 200k w for v dd = 5.0v (see section 1.5. 2) c11, c12 c13 c14 330pf 10nf 100nf r10 160k w r11 - r14 100k w r15 600 w x1 3.579545mhz r16 120k w d1 - d4 1n4004 r17 100k w r18 100k w 20% resistors 1%, capacitors 20% unless otherwise stated. figure 2 : recommended external components for typical application it is re commended that the printed circuit board is laid out with a ground plane in the CMX612 area to provide a low impedance ground connection to the v ss pin and to the decoupling capacitors c8 and c9.
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 7 d/612/3 1.5 general description 1.5.1 mode control logic the CMX612's operating mode and the source of the det and irqn outputs are determined by the logic levels applied to the mode 1 and mode 2 input pins; mode 1 mode 2 mode det o/p from irqn o/p from 0 0 tone alert detect tone alert signal detection. cas tones present. valid ?off - hook? cas or ring or line polarity reversal detection. ringing signal present. 0 1 fsk receive fsk level detection. fsk present. fsk data retiming [1] or ring or line polarity reversal detection. ringing signal present. 1 0 'zero - power' ring or line polarity reversal detection. ringing signal present. ring or line polarity reversal detection. ringing signal present. 1 1 dial tone detect dial tone sig nal detection. both tones present. valid dial tone detected. [1] if enabled. in 'zero - power' mode, power is removed from all of the internal circuitry except for the ring or line polarity reversal detector and the det and irqn outputs. 1.5.2 input signal amplifiers these amplifiers can be used to convert the balanced fsk, tone alert and vmwi signals received over the telephone line to an unbalanced signal of the correct amplitude for the fsk receiver, to ne alert and dial tone detector circuits. figure 3a : input signal amplifier, balanced input configuration the design equations for this circuit are; differential voltage gain v aop / v(b - a) = r8/r6 r6 = r7 = 470k w r10 = 160k w r9 = r8 x r10 / (r8 - r10) the target differential voltage gain depends on the expected signal levels between the a and b wires and the CMX612's internal threshold levels, which are proportional to the supply voltage.
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 8 d/612/3 the cm x612 has been designed to meet the applicable specifications with r8 = 430k w at v dd = 3.0v nominal, rising to 680k w at v dd = 5.0v, and r9 should be 240k w at v dd = 3.0v and 200k w at v dd = 5.0v as shown in section 1.4 and figure 3c. the input signal amplifiers may also be used with an unbalanced signal source as shown in figure 3b. the values of r6 and r8 are as for the balanced input case. figure 3b : input si gnal amplifier, unbalanced input configuration 0 100 200 300 400 500 600 700 800 900 1000 3 3.5 4 4.5 5 r8 and r9 : k ohms r8 r9 nominal v dd (v) figure 3c : input signal amplifier, optimum values of r8 and r9 vs. v dd 1.5.3 bandpass filters these are used to attenuate out of band noise and int erfering signals which might otherwise reach the fsk demodulator, tone alert detector, dial tone detector and level detector circuits. the characteristics of these filters differ in fsk, tone alert and dial tone modes. most of the filtering is provided by switched capacitor stages clocked at 57.7khz or 9.62khz depending on mode of operation. 1.5.4 level detector this block operates by measuring the level of the signal at the output of the bandpass filter, and comparing it against a threshold which depends on whether fsk receive, tone alert detect or dial tone detect mode has been selected. in tone alert detect mode the output of the level detector block provides an input to the tone alert signal detector. in dial tone detect mode the output of the level detector block provides an input to the dial tone signal detector.
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 9 d/612/3 in fsk receive mode the CMX612 det output will be set high when the level has exceeded the threshold for sufficient time. amplitude and time hysteresis a re used to reduce chattering of the det output in marginal conditions. note that in fsk receive mode this circuit may also respond to non - fsk signals such as speech. see section 1.7.1 for definitions of teon and teoff figure 4 : fs k level detector operation 1.5.5 fsk demodulator this block converts the 1200 baud fsk input signal to a logic level received data signal which is output via the rxd pin as long as the data retiming function is not e nabled (see section 1.5.6). this output does not depend on the state of the fsk level detector output. note that in the absence of a valid fsk signal, the demodulator may falsely interpret speech or other extraneous signals as data. 1.5.6 fsk data retim ing the data retiming block extracts the 8 data bits of each character from the received asynchronous data stream, and presents them to the m c under the control of strobe pulses applied to the rxck input. the timing of these pulses is not critical and they may easily be generated by a simple software loop. this facility removes the need for a uart in the m c without incurring an excessive software overhead. the block op erates on a character by character basis by first looking for the mark to space transition which signals the beginning of the start bit, then, using this as a timing reference, sampling the output of the fsk demodulator in the middle of each of the followi ng 8 received data bits, storing the results in an internal 8 - bit shift register. when the eighth data bit has been clocked into the internal shift register, the CMX612 examines the rxck input. if this is low then the irqn output will be pulled low and t he first of the stored data bits put onto the rxd output pin. on detecting that the irqn output has gone low, the m c should pulse the rxck pin high 8 times. the high to low transition at the end of the first 7 of these pulses will be used by the CMX612 to shift the next data bit from the shift register onto the rxd output. at the end of the eighth pulse the fsk demodulator output will be reconnected to the rxd output pin. the irqn output will be cleared the first time the rxck input goes high. thus to use the data retiming function, the rxck input should be kept low until the irqn output goes low; if the data retiming function is not required the rxck input should be kept high. the only restrictions on the timing of the rxck wavef orm are those shown in figure 5a and the need to complete the transfer of all eight bits into the m c within 8.3ms (the time of a complete character at 1200 baud).
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 10 d/612/3 td = internal CMX612 delay; max. 1 m s tclo = rxck low time; min 1 m s tchi = rxck high time; min 1 m s figure 5a : fsk operation with data retiming note that, if enabled, the data retiming block will interpret the fsk channel seizure signal (a sequence of alternating mark and space bits) as valid received characters, with values of 55 (hex). similarly it may interpret speech or other signals as random characters. if the data retiming facility is not required, the rxck input to the CMX612 sh ould be kept high. the asynchronous data from the fsk demodulator will then be connected directly to the rxd output pin, and the irqn output will not be activated by the fsk signal. this case is illustrated in figure 5b. figure 5b : fsk operation with out data retiming (rxck always high) 1.5.7 tone alert detector this block is enabled when the CMX612 is set to tone alert detect mode. it will then monitor the received signal for the presence of simultaneous 213 0hz and 2750hz tones of sufficient level and duration. two digital bandpass filters, centred around 2130hz and 2750hz, are used within the block to give additional rejection of interfering signals. the CMX612 det output will be set high while a tone aler t signal is detected. at the end of the tone alert signal the detector will derespond in 5ms typically. since the deresponse time is governed by a statistical process, there will be occasions when the maximum figure of 17ms is exceeded. when the det out put goes low at the end of the tone alert signal, then if the det output had been high for a time within the cas qualifying time tqcas limits (see section 1.7.1) , then the irqn output will be pulled low and will remain low until the CMX612 is switched out of tone alert detect mode. note that the tqcas timing has been optimised for the detection of 75 to 85ms tone alert (cas) signals used in off -
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 11 d/612/3 hook applications, the longer (88 to 110ms) tone alert signal employed by bt for on - hook applications will not ne cessarily cause irqn to go low. see section 1.7.1 for definitions of tton, ttoff and tqcas figure 6 : tone alert detector operation 1.5.8 dial tone detector this block is enabled when the cmx 612 is set to dial tone detect mode. it will then monitor the received signal for the presence of simultaneous 350hz and 440hz tones of sufficient level and duration. two digital bandpass filters, centred around 350hz and 440hz, are used within the block to give additional rejection of interfering signals. the CMX612 det output will be set high while a dial tone signal is detected. at the end of the dial tone signal the detector will derespond in 24ms typically. since the deresponse time is governed by a statistical process, there will be occasions when the maximum figure of 33ms is exceeded. when the det output goes high the irqn output will be pulled low and will remain low until the CMX612 is switched out of dial tone detect mode. note that the dial t one detect timing has been optimised for the detection of >90ms signals. shorter dial tone signals will not necessarily be detected. see section 1.7.1 for definitions of tdon and tdoff figure 7 : dial tone detector operation
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 12 d/612/3 1. 5.9 ring or line polarity reversal detector these circuits are used to detect the line polarity reversal and ringing signals associated with the calling line identification protocol. figure 8 illustrates their use in a typical application. figure 8 : ring or line polarity reversal operation when no signal is present on the telephone line, rd will be at v ss and rt pulled to v dd by r5 so the output of the schmitt trigger 'b' will be low. the ring signal is usually applied at the subscriber's exchange as an ac voltage inserted in series with one of the telephone wires and will pass through either c3 and r3 or c4 and r4 to appear at the top end of r1 (point x in figure 8) in a rectified and attenuated form. the signal at point x will be further attenuated by the potential divider formed by r1 and r2 before being applied to the CMX612 input rd . if the amplitude of the signal appearing at rd is greater than the input thre shold (vthi) of schmitt trigger 'a' then the n transistor connected to rt will be turned on, pulling the voltage at rt to v ss by discharging the external capacitor c5. the output of the schmitt trigger 'b' will then go high, activating the det and/or irqn outputs depending on the states of the mode 1 and mode 2 inputs. the minimum amplitude ringing signal that is certain to be detected is:
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 13 d/612/3 ( 0.7 + vthi x [r1 + r2 + r3] / r2 ) x 0.707 vrms where vthi is the high - going threshold voltage of the schmitt trigger a (see section 1.7). with r1, r3 and r4 all at 470k w , as figure 2, setting r2 to 68k w will guarantee detection of ringing signals of 40vrms and above for v dd over the range 2.7 to 5.5v. a line polari ty reversal may be detected using the same circuit but there will be only one pulse at rd. the bt specification sin242 says that the circuit must detect a +15v to - 15v reversal between the two lines slewing in 30ms. for a linearly changing voltage at the i nput to c3 (or c4), then the voltage appearing at the rd pin will be: dv/dt x c3 x [ 1 - exp( - t/t) ] x r2 where t = c3 x (r1 + r2 + r3) and dv/dt is the input slew rate. for dv/dt = 500v/sec (15v in 30ms), r1, r3 and r4 all 470k w and c3, c4 both 0.1 m f as figure 2, then setting r2 to 390k w will guarantee detection at v dd = 5.5v. if the time constant of r5 and c5 is large enough then the voltage on rt will remain below the threshold of the 'b' schmitt trigger keeping the det and/or irqn outputs active for the duration of a ring cycle. the time for the voltage on rt to charge from v ss towards v dd can be derived from the formula v rt = v dd x [1 - exp( - t/(r5 x c5)) ] as the schmitt tr igger high - going input threshold voltage (vthi) has a minimum value of 0.56 x v dd , then the schmitt trigger b output will remain high for a time of at least 0.821 x r5 x c5 following a pulse at rd. using the values given in figure 2 (470k w and 0.33 m f) gives a minimum time of 100 ms (independent of v dd ), which is adequate for ring frequencies of 10hz or above. if necessary, the c can distinguish between a ring and a reversal by timing the length of the irq n or det output. 1.5.10 xtal osc and clock dividers frequency and timing accuracy of the CMX612 is determined by a 3.579545mhz clock present at the xtal pin. this may be generated by the on - chip oscillat or inverter using the external components c1, c2 and x1 of figure 2, or may be supplied from an external source to the xtal input, in which case c1, c2 and x1 should not be fitted. the oscillator is turned off in 'zero - power' mode. if the clock is provid ed by an external source which is not always running, then the mode 1 input must be set high and the mode 2 input must be set low when the clock is not available. failure to observe this rule may cause a significant rise in the supply current drawn by cmx6 12 as well as generating undefined states of the rxd, det and irqn outputs.
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 14 d/612/3 1.6 application notes 1.6.1 'on - hook' operation the systems described in this section operate w hen the telephone set is not in use (on - hook) to display the number of a calling party before the call is answered. british telecom system figure 9a illustrates the line signalling and CMX612 i/o signals for the bt on - hook calling line id system as defi ned in bt specifications sin227 and sin242 part 1. a similar system is described in ets 300 659 - 1 section 6.1.2c. and ets 300 778 - 1. the tone alert signal consists of simultaneous 2130hz and 2750hz tones, the 'chan seize' signal is a '1010..' fsk bit sequ ence. not shown are the requirements for ac and dc loads, including a short initial current wetting pulse, to be applied to the line 20ms after the end of the tone alert signal and to be maintained during reception of the fsk signal. note that, for simplic ity of presentation, the data retiming function is not used in figure 9a (rxck is kept high). figure 9a : bt on - hook system signals bellcore system figure 9b illustrates the line signalling and CMX612 i/o signals for the bellcore on - hook caller id system as defined in bellcore documents gr - 30 - core and sr - tsv - 002476 and also in ets 300 659 - 1 section 6.1.1. and ets 300 778 - 1. as for the bt system, the 'chan seize' signal is a '1010..' fsk bit sequence. the bellcore specifications do not require ac or dc line terminations while the fsk data is being received, however ets 300 659 - 1 and ets 300 778 - 1 allow for the possibility of an ac termination being applied. note that, for simplicity of presentation, the data retiming function is not used in figure 9b (rxck is kept high).
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 15 d/612/3 figure 9b : bellcore on - hook system signals other on - hook systems ets 300 659 - 1 and ets 300 778 - 1 also allow for systems where the fsk transmission is preceded by a dual tone alerting signal similar to that used by bt but witho ut a line reversal (section 6.1.2a) or by a ringing pulse alerting signal (section 6.1.2b). the u.k. cca (cable communications association) specification tw/p&e/312 precedes the fsk signals by a 200 to 450ms ring burst. the use of ac and dc line terminati ons during fsk reception is optional. mercury communications ltd. specification mnr 19 allows for either the bt system or that specified by cca. as these are all slight variants on the bt and bellcore systems, they can also be handled by the CMX612.
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 16 d/612/3 figure 9c : flow chart for on - hook operation of CMX612
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 17 d/612/3 1.6.2 'off - hook' operation the cidcw (calling identity on call waiting) system described in this section operates when the telephone s et is in use (off - hook) to display the number of a waiting caller without interrupting the current call. bellcore documents gr - 30 - core and sr - tsv - 002476, bt specifications sin227 and sin242 part 2 and ets 300 - 659 - 2 all describe similar systems in which a successful cidcw transaction consists of a sequence of actions between the cpe (customer premises equipment - e.g. a telephone) and the central office as indicated in figure 10a. a. normal conversation with both near and far end voice present. b. centr al office mutes far end voice, sends cas and becomes silent. c. cpe recognises cidcw initiation and mutes near end voice and keypad. d. cpe sends dtmf ack to central office to signal its readiness to receive fsk data. e. central office recognises ack and s ends fsk caller id data to cpe. f. cidcw transaction is complete. cpe unmutes near end voice and the central office unmutes far end voice, returning to normal conversation. figure 10a : cidcw transaction from near end cpe perspective the cas signal is transmitted by the central office to initiate a cidcw transaction and consists of an 80ms burst of simultaneous 2130hz and 2750hz tones. cas detection is very important because a ?missed? signal causes caller id information to be lost and a false signal de tection produces a disruptive tone which is heard by the far end caller. because the cas signals must be detected in the presence of conversations which both mask and masquerade as the tone signals, this function is difficult to accomplish correctly. beca use the numbers of false responses (talk - offs) and missed signals (talk - downs) are related to the speech levels at the CMX612 input, and because the level of near end speech from the local handset is normally greater than that of far end speech coming from the central office, a further improvement in overall performance can be obtained by taking the CMX612?s audio input from the receive side of the telephone set hybrid where this is possible. the internal algorithms used by the CMX612 to drive the det and irqn outputs in tone alert detect mode have been optimised for the detection of off - hook cas signals in the presence of speech when used according to the following principles: 1. if it is possible to mute the local speech from the microphone rapidly (with in 0.5ms) without introducing noise (i.e. where the cidcw equipment is built into the telephone set) then this should be done whenever the CMX612 is in tone detect mode and the det output is high. doing this will markedly reduce the number of false respons es generated by local (near end) speech. note that the det output is not used for any other purpose in an off - hook application when the CMX612 is set to tone alert detect mode.
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 18 d/612/3 2. the irqn output going low when in tone alert detect mode indicates that a ca s has been detected. the local handset and keypad should then be muted as required by the bellcore specification and the CMX612 switched to fsk receive mode to be ready to receive the fsk data, doing this will also clear the irqn output. 3. the CMX612?s d et output should be monitored for a period of 50ms after changing to fsk receive mode, before sending the ack signal, and the transaction abandoned if the det output goes high during this time, which would be the case if a false cas detect had been caused by far end speech. figure 10b : flow chart for off - hook operation of CMX612
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 19 d/612/3 1.6.3 vmwi operation vmwi is an indicator for a group of services that is offered by telephone companies to their cu stomers. for example, it allows voice messages to be stored for later retrieval by the subscribing customer (voice - mail notification). messages may be entered into a mailbox by any of the following methods: 1. a call placed to the customer?s line is unanswer ed after a certain number of rings and is then forwarded to the voice - mail system (forward on do not answer). 2. a call placed to the customer?s line receives a busy signal and is then forwarded to the voice - mail system (forward on busy). 3. a message is forward ed to the customer?s voice - mail box by a party directly through the voice - mail system, without the customer?s line ever being called. in each case, the presence of messages waiting in the customer?s voice - mail box is indicated to the customer by generatio n of a vmwi signal. in bellcore systems, the identification of a vmwi signal can be performed by detecting either a stuttered dial tone (off - hook) or an fsk signal (on - hook). sdt mode when there is a message waiting in a customer?s voice - mail box, the tel ephone company?s central office (co) switch may apply a special dial tone to the customer?s line when it is taken off - hook. the special dial tone is called stuttered dial tone and is generally characterised as follows: 1. steady dial tone frequencies (350hz + 440hz). 2. steady dial tone amplitude up to - 12dbv per tone applied from the central office (co) switch to the line. 3. a cadenced signal of 100ms on, 100ms off, repeated between 3 and 10 times and then steady dial tone. according to the us - fcc alameda order, the customer premises equipment (cpe) will make a stuttered dial tone check either: 1. when the subscriber takes the phone off - hook to make a call or 2. within 4 minutes of an unanswered call or 3. within 30 seconds of a completed call. the telephone is taken of f - hook to make a stuttered dial tone check. the cpe then puts the CMX612 from ?zero - power? mode into dial tone detect mode. if both dial tones are detected, then the det output will be set high and the irqn output will be set low. the det output may then be polled every 40 - 80ms to check if it has been cleared. the det output will only be cleared if one or both tones are removed. if this occurs within 100ms, a counter may be incremented in the cpe (external to the CMX612) and the irqn output should then b e cleared. this may be done by taking the CMX612 out of dial tone detect mode into ?zero - power? mode and back into dial tone detect mode. on receiving another interrupt, the polling routine described above should be repeated. if the counter reaches an app ropriate value (e.g. 10) within an appropriate time (e.g. 2.3 seconds) then stuttered dial tone has been detected and a visual message indicator will then be lit by the cpe. other algorithms to detect stuttered dial tone (e.g. continuous polling of the det output once an interrupt has been received) are also possible.
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 20 d/612/3 class (fsk) mode when there is a message waiting in a customer?s voice - mail box, the telephone company?s central office (co) switch may send on - hook fsk data to the customer?s line. this can be received by the CMX612 and used to indicate waiting voice - mail (voice - mail notification) and other class services, by using the fsk receive mode. figure 11 : flow chart for vmwi - sdt operation of CMX612
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 21 d/612/3 1.7 performance specificatio n 1.7.1 electrical performance 1.7.1.1 absolute maximum ratings exceeding these maximum ratings can result in damage to the device. min. max. units s upply (v dd - v ss ) - 0.3 7.0 v voltage on any pin to v ss - 0.3 v dd + 0.3 v current into or out of v dd and v ss pins - 30 +30 ma current into or out of any other pin - 20 +20 ma e3 package min. max. units total allowable power dissipation at tam b = 25c 300 mw ... derating 5 mw/c storage temperature - 55 +125 c operating temperature - 40 +85 c p6 package min. max. units total allowable power dissipation at tamb = 25c 800 mw ... derating 13 mw/c storage temperat ure - 55 +125 c operating temperature - 40 +85 c 1.7.1.2 operating limits correct operation of the device outside these limits is not implied. notes min. max. units supply (v dd - v ss ) 2.7 5.5 v operating temperature 2 - 40 +85 c xtal fre quency 1 3.575965 3.583125 mhz notes: 1. an xtal frequency of 3.579545mhz 0.1% is required for correct tone alert and fsk detection. 2. operating temperature range - 10c to +60c at v dd < 3.0v.
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 22 d/612/3 1.7.1.3 operating characteristics details in this se ction represent design target values and are not currently guaranteed . for the following conditions unless otherwise specified: v dd = 2.7v at tamb = - 10 to +60c and v dd = 3.0v to 5.5v at tamb = - 40c to +85c, xtal frequency = 3.579545mhz 0.1%, 0db v corresponds to 1.0vrms. notes min. typ. max. units dc parameters i dd (in ?zero - power? mode) at v dd = 5.0v 1, 2 0.02 tbd a i dd (not in ?zero - power? mode) at v dd = 3.0v 1 0.5 tbd ma i dd (not in ?zero - power? mod e) at v dd = 5.0v 1 1.0 tbd ma logic ?1? input level (rxck and xtal inputs) 70% v dd logic ?0? input level (rxck and xtal inputs) 30% v dd logic input leakage current (vin = 0 to v dd ) - 1.0 +1.0 a excluding xtal input outpu t logic ?1? level (l oh = 360a) v dd - 0.4v v output logic ?0? level (l ol = 360a) 0.4 v irqn o/p ?off? state current (vout = v dd ) 1.0 a schmitt trigger input thresholds, see fig 12 high going (vthi) 0.56v dd 0.56v dd +0.6v v low going (vtlo) 0.44v dd - 0.6v 0.44v dd v tone alert detector ?low? tone nominal frequency 2130 hz ?high? tone nominal frequency 2750 h z start of tone alert signal to det high time 55.0 ms (fig 6 tton) end of tone alert signal to det and irqn low time (fig 6 ttoff) 0.5 5.0 17.0 ms det high time to ensure irqn goes low 8.0 45.0 ms (fig 6 tqcas) to ensure detection: 3 ?low? tone frequency tolerance 0.5 % ?high? tone frequency tolerance 0.5 % level (total) 4 - 40.0 - 2.2 dbv 2750hz tone level wrt 2130hz tone level - 6.0 +6.0 db signal to noise ratio 5 20.0 db dual tone burst duration for det output 75.0 ms dual tone burst duration to ensure irqn goes low 75.0 85.0 ms to ensure non - detection: 6 ?low? tone frequency tolerance 75.0 hz ?high? tone frequency tolerance 95.0 hz level (total) 4 - 46.0 dbv dual tone burst duration 45.0 ms
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 23 d/612/3 notes min. typ. max. units fsk receiver transmission rate 1188 1200 1212 baud v23 mark (logical 1) frequency 1280 1300 1320 hz v23 space (logical 0) frequency 2068 2100 2132 hz bell202 mark (logical 1) frequency 1188 1200 1212 hz bell202 space (logical 0) frequen cy 2178 2200 2222 hz valid input level range 4 - 40.0 - 8.0 dbv acceptable twist (mark level wrt space level) v23 - 6.0 +6.0 db bell202 - 10.0 +10.0 db acceptable signal to noise ratio v23 5 20 .0 db bell202 5 30.0 db level detector ?on? threshold level 4 - 40.0 dbv level detector ?off? to ?on? time (fig 4 teon) 25.0 ms level detector ?on? to ?off? time (fig 4 teoff) 8.0 ms input signal amplifier input impedance 7 10.0 m w voltage gain 500 v/v xtal input ?high? pulse width 8 100 ns ?low? pulse width 8 100 ns dial tone detector ?low? tone nominal frequency 350 hz ?high? tone nominal frequency 440 h z start of dial tone signal to det high time 60.0 ms (fig 7 tdon) end of dial tone signal to det and irqn low time (fig 7 tdoff) 3.0 24.0 33.0 ms det high time (100ms tone duration) 1.3 40 .0 60.0 ms to ensure detection: 3 ?low? tone frequency tolerance 7.0 hz ?high? tone frequency tolerance 7.0 hz level (per tone) 4 - 31.2 - 12.2 dbv 350hz tone level wrt 440hz tone level - 6.0 +6.0 db signal to noise ratio 5 20.0 db dual tone burst duration for det output 9 80.0 ms dual tone burst duration to ensure irqn goes low 9 80.0 ms to ensure non - detection: 6 ?low? tone frequency tolerance - 45.0 +30.0 hz ?high? tone frequency tolerance - 30.0 +40.0 hz level (total) 4 - 36.0 dbv dual tone burst duration 30.0 ms
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 24 d/612/3 notes: 1. at 25 c, not including any current drawn from the CMX612 pins by external circuitry other than x1, c1 and c2. 2. rd, rxck, mode 2 inputs at v ss , mode 1 input at v dd . see also figur e 13. 3. all conditions must be met to ensure detection. 4. for v dd = 3.3v with equal level tones and with the input signal amplifier external components as section 1.4. the internal threshold levels are proportional to v dd . to cater for other supply vol tages or different signal level ranges the voltage gain of the input signal amplifier should be adjusted by selecting the appropriate external components as described in section 1.5 5. flat noise in 300 - 3400hz band for v23, 200 - 3200hz for bell202. 6. meeting any of these conditions will ensure non - detection. 7. open loop, small signal low frequency measurements. 8. timing for an external input to the clock/xtal pin. 9. tone duration between 80ms and 90ms will normally give 100% detection. however, under cer tain conditions (e.g. exact 4:5 ratio between tone frequencies and adverse twist conditions) up to 0.3% of tones may not be detected. above 90ms, detection is 100%.
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 25 d/612/3 0 0.5 1 1.5 2 2.5 3 3.5 4 3 3.5 4 4.5 5 5.5 v dd (v) vin (v) vthi vtlo figure 12 : schmitt trigger typical input voltage thresholds vs. v dd 0.0001 0.001 0.01 0.1 1 10 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 temperature ( o c) i dd (a) figure 13 : typical 'zero power' i dd vs. temperature (v dd = 5.0v)
calling line identifier with vmwi CMX612 ? 2002 consumer microcircuits limited 26 d/612/3 1.7.2 packaging figure 14 : 20 - pin tssop (e3) mechanical outline: order as part no. CMX612e3 figure 15 : 22 - pin dil (p6) mechanical outline: order a s part no. CMX612p6
calling line identifier with vmwi CMX612 handling precautions: this product includes input protection, however, precautions should be taken to prevent device damage from electro - static discharge. cm l 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 o f 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 t elephone: +44 (0)1621 875500 telefax: +44 (0)1621 875600 e - mail: sales@cmlmicro.co.uk http://www.cmlmicro.co.u k

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