1 zarlink semiconductor inc. zarlink, zl and the zarlink semiconductor logo are trademarks of zarlink semiconductor inc. copyright 1990-2006, zarlink semiconductor inc. all rights reserved. features ? performs ask (amplitude shift keyed) modulation and demodulation ? 32 khz carrier frequency ? up to 2 kbit/s full duplex data transfer rate ? on-chip oscillator ? on-chip tone caller for alerting functions ? adjustable tone caller frequencies ? selectable self-loop test mode ? 5v/2.5ma power supply ?iso 2 -cmos and switched capacitor technologies ? 18 pin dip applications ? simultaneous data and voice communication in pabxs ? 2 kbit/s data modem ? "smart" telephone sets description the mt8840 is a carrier over voice modem which allows simultaneous transfer of voice and data over a single pair of wires. data is transferred on an amplitude shift keyed (ask) 32 khz carrier. on-chip filters remove voice frequency signals from the received composite voice and data signal prior to demodulation. the modulating signal is a bit stream with a typical data rate of 2 kbit/s. in addition, the device contains a two tone warbler which functions as a telephone ringer. the device is fabricated in zarlink?s double-poly iso 2 - cmos technology utilizing switched-capacitor techniques. mar 2006 ordering information mt8840ae 18 pin pdip tubes mt8840as 18 pin soic tubes mt8840asr 18 pin soic tape & reel mt8840ae1 18 pin pdip* tubes mt8840asr1 18 pin soic* tape & reel * pb free matte tin 0 c to +85 c iso 2 -cmos mt8840 data over voice modem data sheet figure 1 - functional block diagram osc1 osc2 ck32 etc mtc fatc txdi rxdo det crx v dd v ss v ref loop tco txo rxe rxi timing and control tone caller modulator tx bandpass filter tx post- filter rx pre- filter r o u t i n agc g rx bandpass filter demodulator
mt8840 data sheet 2 zarlink semiconductor inc. figure 2 - pin connections pin description pin # name description 1 det demodulator detection level adju st input (analog). internal resistor divider applies 2.36 v in open circuit condition. connection of ex ternal resistor will vary detect level. 2 crx external agc time constant adjust input (analog). connect external capacitor to v ss . 3 rxi modulated receive signal input (analog). biased at v ref . 4 rxe receive enable input (digital) wi th internal pull up. active high. 5 loop self-test mode select input (digital) with internal pull down. active high. 6v ref internal reference supply voltage input (analog) . 7 txo modulated transmit carrier output (analog). 8 txdi transmit data input (digital). 9v ss negative power supply. 10 fatc tone caller center frequency adjust input (analog). 11 tco tone caller output (digital). 12 mtc mute tone caller input (digital) with internal pull down. active high. 13 etc enable tone caller input (digital) wi th internal pull down. active high. 14 ck32 32 khz data strobe output (digital). 15 osc1 clock input 3.579545 mhz crystal connected between these pins completes internal oscillator. 16 osc2 clock output to drive external devices. 17 rxdo receive data output (dig ital). synchronized to ck32. 18 v dd positive power supply. 1 2 3 4 5 6 7 8 9 10 18 17 16 15 14 13 12 11 det crx rxl rxe loop vref txo txdi vss vdd rxdo osc2 osc1 ck32 etc mtc tco fatc 18 pin plastic dip/soic
mt8840 data sheet 3 zarlink semiconductor inc. functional description the mt8840 contains the modulator and demodulator circ uitry for 32 khz ask signalling as well as a two-tone warbler (tone caller) to replace the fu nction of the mechanical telephone ringer. a 32 khz carrier is 100% amplitude modulated by the digital bit stream applied to input txdi. this results in an amplitude shift keyed (ask) 32 khz carrier. a logical high at txdi disables the carrier a nd a logical low enables it. the digitally modulated waveform is shaped by the tx bandpass filter and smoothed by the tx post filter. the signal then enters the routing block wh ere it is transferred to the txo output. the modulated 32 khz receive signal is applied to rxi. with a logical low applied to loop and a logical high applied to rxe, receive signals ar e routed to the rx prefilter. hi gh frequencies are removed by the rx prefilter to prevent aliasing in the switched ca pacitor rx bandpass filter. voice signals are removed by the bandpass filter which is followed by an agc circuit. this provides a dynamic range of 20 db for the receiver. an external 1 f capacitor connected from crx to v ss is required to control the agc attack and decay time constants. data is recovered from the received signal in the demodu lator. the minimum voltage level to which the demodulator responds may be adjusted by connecting a resistor from det to v dd or v ref . since det is the input to a comparator, noise should be kept to a minimum at this pin. the recovered receive data is synchronized to the leading edge of the 32 khz clock (availab le at ck32) before appearing at rxdo. when in loop around mode, the rx prefilter input is internally disconnected from the rxi input pin and connected to txo. the transmitter output is still available at txo. a two tone warbling audio signal is available at tco w hen the tone caller enable input (etc) is high. tco is internally clamped to v ref when the tone caller is disabled. the tone ou tput can be attenuated by 20 db if a logical high is applied to the tone caller mute input (mtc). applications figures 3 through 5 show how the mt8840 may be ut ilized to transfer data and voic e simultaneously over a single pair of wires in digital or analog pabxs and "smart " telephone sets. in all three figures a microprocessor sends/receives data to/from the mt8840 via a uart which conver ts the data format from parallel-to-serial or serial- to-parallel for the transmit and receive direct ions, respectively. in the receive direction the mt8840 has on- board filters to reject voice-band sign als leaving only the 32 khz carrier. this carrier is then demodulated to recover the received data. in the transmit direction the data to be sent is modulated and passed on to a summing circuit which sums the modulated 32 khz carrier and voiceband signa ls for transmission over the telephone line. in the pabx the filter/codec has filters which reject the 32 khz carrier from the received composite voice and data signal allowing only voiceband signals to pass through which ar e then pcm encoded for digital switching. however, in both the analog pabx and smart telephone set, lowpass filt ers could be included to bandlimit the received signal leaving only voice signals to be passed on to the switch array or handset earpiece.
mt8840 data sheet 4 zarlink semiconductor inc. figure 3 - digital pabx block diagram figure 4 - analog pabx block diagram micro- processor uart tx data rx data tx rx summing circuit 2w/4w converter telephone line pcm highway mt8840 filter/ codec (mt896x) tx rx micro- processor uart tx data rx data tx rx summing circuit 2w/4w converter telephone line (optional) low- pass filter analog switch array (mt8804) tx rx to another telephone extension slic mt8840
mt8840 data sheet 5 zarlink semiconductor inc. figure 5 - smart telephone set block diagram figure 6 - crystal oscillator connect ions for driving multiple mt8840s tx rx summing circuit telephone line mt8840 micro- processor uart tx data rx data low- pass filter handset (optional) 2w/4w converter when a single crystal is shared among a number of mt8840 devices, osc1 and osc2 should be a.c. coupled with a 1000 pf capacitor as shown above. this capacitor is not needed between the device with the crystal and the first driven device. a capacitor shoul d be used in the first stage whenever such a ch ain of devices is driven from a clock inst ead of a crystal. a 33 pf capacitor should b e connected between osc1 and vss to compensate for the load on osc2. v dd v ss osc1 osc2 mt8840 c=33pf mt8840 osc1 osc2 c=1000pf mt8840 osc1 osc2 c=1000pf ? ? ?
mt8840 data sheet 6 zarlink semiconductor inc. * exceeding these ratings may cause permanent damage. func tional operation under these conditions is not implied. absolute maximum ratings* parameter symbol min. max. unit 1 supply voltage v dd -v ss -0.3 +7.0 v 2 voltage on any pin v max v ss -0.3 v dd +0.3 v 3 current on any pin i max 20 ma 4storage temperature t s -65 +150 c 5 package power dissipation p diss 850 mw recommended operating conditions parameter symbol min. typ. max. unit 1 operating supply voltages v dd 4.75 5 5.25 v 2v ref 0.4v dd v 3 operating supply currents i dd 2.5 5.0 ma 4i ref 200 a 5 operating temperature t o 0+85 c 6 load capacitance (txo) c l 50 pf 7 load resistance (txo) r l 10 k ?
mt8840 data sheet 7 zarlink semiconductor inc. notes : 1. voltage specified is generated internally and m easured with no external components connected to det d.c. characteristics - v dd = 5.0 v 5% v ss =0v t = 0 - 85 o c (all voltages are referenced to v ss /gnd) characteristics sym. min. typ. max. unit test conditions 1 d i g i t a l i / o input current i in 10 av in = 0 to v dd 2 input low voltage v il 01.5v 3 input high voltage v ih 3.5 5.0 v 4 output low voltage v ol 0.4 v i ol = 0.4ma 5 output high voltage v oh 4.6 v i oh = 0.4ma 6 output drive current 7 n channel sink (except osc2) i ol 0.4 ma v ol = 0.4v 8osc2 0.1 ma 9 p channel source (except osc2) i oh 0.4 ma v oh = 4.6v 10 osc2 0.1 ma 11 a n a l o g i / o input current (rxi, fatc) i in 10 av in = 0 to 5.0v 12 input resistance (fatc) r in 500 k ? 13 (det to v dd )170k ? 14 (det to v ref )23k ? 15 input capacitance (rxi) c in 50 pf 16 (fatc) 10 pf 17 any digital input 5.0 7.5 pf 18 output resistance (txo) r o 100 ? 19 (tco) 3 k ? mtc = 0 20 (tco) 30 k ? mtc = 1 21 output offset voltage (txo) v o 25 200 mv 22 output voltage (det) v o 2.20 2.36 2.55 v see note 1
mt8840 data sheet 8 zarlink semiconductor inc. a.c. characteristics - v dd =5.0v 5% v ss =0v t=0 - 85 c (all voltages are referenced to v ss /gnd) characteristics sym. min. typ. max. unit test conditions 1 d i g i t a l i / o crystal/clock frequency f c 3.5759 3.5795 3.5831 mhz osc1, osc2 2 clock input (osc 1) 3rise time t lhci 100 ns 10% - 90% of (v dd - v ss ) 4fall time t hlci 100 ns 5 duty cycle dc ci 40 50 60 % 6 clock output (osc 2) 7rise time t lhco 100 ns c l = 30pf, 3.58mhz ext. 8fall time t hlco 100 ns clock to osc1 9 duty cycle dc co 50 % 10 capacitive load c lco 30 pf 11 clock output (ck32) f c32 32508 32541 32574 hz fc = 3.5795mhz 12 rise time t lh32 100 ns 10% - 90% of (v dd - v ss ) 13 fall time t hl32 100 ns c l = 100pf 14 duty cycle dc 32 50 % 15 capacitive load c l32 100 pf 16 t o n e c a l l e r warbler frequency (tco) f w 7.935 7.945 7.955 hz fc = 3.5795mhz 0.1% 17 low tone frequency f lt 352 390 428 hz fatc = 0, f c = 3.5795mhz 18 1036 1148 1260 hz fatc = v dd , f c = 3.5795mhz 19 high tone frequency f ht 440 487 535 hz fatc = 0, f c = 3.5795mhz 20 1295 1434 1574 hz fatc = v dd , f c = 3.5795mhz 21 harmonic relationship f ht /f lt 1.25 22 warbler output (tco) 23 rise time t lhwo 500 ns 100k ? load to v ref 24 fall time t hlwo 500 ns c l = 30pf, mtc = 0 25 duty cycle dc wo 50 % 26 output level (tco) v tcc v dd v pp mtc = 0 27 0.625 v pp mtc = 1 (100k ? load to v ref ) 28 m o d u l a t o r modulated frequency f mod 32541 hz 29 output level (txo) v txo 225 250 270 mv pp v dd = 5v 30 output level (txo) 31 variation vs. v dd v txo 100 % 32 transmit data input (txdi) 33 rise time t lhtxdi 100 ns 34 fall time t hltxdi 100 ns 35 data rate (txdi) f data 2 k/bits see note 1
mt8840 data sheet 9 zarlink semiconductor inc. notes: 1. all a.c. parameters are base d on a typical data rate of 2 kbit/s. 2. measured with no external resistor to det input . detection level internally set to 2.36 v typical. 36 d e m o d u l a t o r input impedance (rxi) z in 50 k ? 32 khz input frequency 37 valid input level - data (rxi) v rxi 40 400 mv pp see note 2 38 valid input level - data + voice v rxi 3.0 v pp 39 receive data output (rxdo) f data 2kbit/s 40 rise time 100 ns 10% - 90% of (v dd - v ss ) 41 fall time 100 ns c l = 100pf 42 capacitive load 100 pf 43 duty cycle 40 50 60 % 44 d e m o d inband noise rejection (s/n) 12 db input sig. (rxi) = 400mv pp 45 attenuation to voice signals 40 db f in = 0 - 5khz 46 detect filter q q 3.8 47 detector center frequency 32 khz a.c. characteristics - v dd =5.0v 5% v ss =0v t=0 - 85 c (all voltages are referenced to v ss /gnd) characteristics sym. min. typ. max. unit test conditions
www.zarlink.com information relating to products and services furnished herein by zarlink semiconductor inc. or its subsidiaries (collectively ?zarlink?) is believed to be reliable. however, zarlink assumes no liability for errors that may appear in this publication, or for liability otherwise arising from t he application or use of any such information, product or service or for any infringement of patents or other intellectual property rights owned by third parties which may result from such application or use. neither the supply of such information or purchase of product or service conveys any license, either express or implied, u nder patents or other intellectual property rights owned by zarlink or licensed from third parties by zarlink, whatsoever. purchasers of products are also hereby notified that the use of product in certain ways or in combination with zarlink, or non-zarlink furnished goods or services may infringe patents or other intellect ual property rights owned by zarlink. this publication is issued to provide information only and (unless agreed by zarlink in writing) may not be used, applied or re produced for any purpose nor form part of any order or contract nor to be regarded as a representation relating to the products or services concerned. the products, t heir specifications, services and other information appearing in this publication are subject to change by zarlink without notice. no warranty or guarantee express or implied is made regarding the capability, performance or suitability of any product or service. information concerning possible methods of use is provided as a guide only and does not constitute any guarantee that such methods of use will be satisfactory in a specific piece of equipment. it is the user?s responsibility t o fully determine the performance and suitability of any equipment using such information and to ensure that any publication or data used is up to date and has not b een superseded. manufacturing does not necessarily include testing of all functions or parameters. these products are not suitable for use in any medical products whose failure to perform may result in significant injury or death to the user. all products and materials are sold and services provided subject to zarlink?s conditi ons of sale which are available on request. purchase of zarlink?s i 2 c components conveys a licence under the philips i 2 c patent rights to use these components in and i 2 c system, provided that the system conforms to the i 2 c standard specification as defined by philips. zarlink, zl and the zarlink semiconductor logo are trademarks of zarlink semiconductor inc. copyright zarlink semiconductor inc. all rights reserved. technical documentation - not for resale for more information about all zarlink products visit our web site at
|
