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Datasheet File OCR Text: |
obsolescence notice this product is obsolete. this information is available for your convenience only. for more information on zarlink?s obsolete products and replacement product lists, please visit http://products.zarlink.com/obsolete_products/
1 features programmable gain, network balance and impedance transformerless 2-4 wire conversion constant current with constant voltage fallback for long loop capability pin compatible with mh88632, mh88620 and MH88628 unbalanced detection (tip, ring ground sensing) auto ring trip with zero crossing on-hook transmission (ani) capability compatible with requirements of ccitt, doc/fcc and csa/ul excellent power dissipation (sil vertical mounting) 12/16khz meter pulse injection control solid state tip/ring reversals ringing ampli?r applications on/off premise pbx line cards did (direct inward dial) line cards central of?e line cards description the zarlink MH88628 slic provides all of the functions required to interface 2-wire off premise subscriber loops to a serial tdm, pcm, switching network of a modern pbx. the MH88628 is manufactured using thick-?m hybrid technology which offers high voltage capability, reliability and high density resulting in signi?ant printed circuit board area savings. a complete c.o. line card can be implemented with very few external components. shk ns n2 natt ud tf2 tf1 tip rf2 rf1 ring n1 lca vdd vrly vee agnd unbalanced detection decoder circuit driver circuitry and speech circuit ringing external signal input loop current set switch-hook threshold set switch-hook detect impedance network ring filter 2-4 wire conversion gain adjust vbat lgnd amplifier rngd rd sel1 sel2 acri dcri esi ese z600 z1 z900 z2 grx1 grx0 rx gtx1 gtx0 tx matched feed resistors issue 5 april 1995 ordering information MH88628 40 pin sil package 0 c to 70 c figure 1 - functional block diagram MH88628 central of?e slic preliminary information MH88628 preliminary information 2 figure 2 - pin connections pin description pin # name description 1 tip tip lead. connects to the ?ip lead of subscriber line. 2 ring ring lead . connects to the ?ing lead of the subscriber line. 3 tf1 tip feed 1. access point for balanced ringing. normally connects to tf2. 4 tf2 tip feed 2. access point for balanced ringing. normally connects to tf1. 5 rf1 ring feed 1. access point for balanced ringing. normally connects to rf2. 6 rf2 ring feed 2. access point for balanced ringing. normally connects to rf1. 7 lgnd battery ground . vbat return path. connected to system s energy dumping ground. 8 lca current limit set (input). the current limit is set by connecting an external resistor to ground. for 30ma default current, this pin is tied to gnd. 9 vbat battery voltage . typically -48vdc is applied to this pin. 10 dcri dc ringing voltage input . a continuous 120vdc is applied to this input. 11 rgnd relay driver ground connection. 12 vrly relay supply voltage connection . 13 rd ring drive (output). connects to ring relay coil. 14 sel1 select 1 (input). refer to table 5 15 sel2 select 2 (input). refer to table 5. 16 esi external signal input. 12/16khz meter pulse input. 17 ese external signal enable. applies the external signal to the line. 18 agnd analog ground. vdd and vee return path. 19 natt network balance at+t node. connects to n1 for a network balance impedance of at&t compromise (350 ? + 1k ? // 210nf); the device s input impedance must be set to 600 ? . this node is active only when ns is at logic high. this node should be left open circuit when not used. 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 n2 z900 z1 z2 tx rx gtx0 gtx1 grx0 grx1 acri z600 ns shk ud ic ic ic vee vdd tip ring tf1 tf2 rf1 rf2 lgnd lca vbat dcri rgnd vrly rd sel1 sel2 esi ese agnd natt n1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 preliminary information MH88628 3 20 n1 network balance node 1(input). 0.1 times the impedance between pins n1 and n2 must match the device s input impedance, while 0.1 times the impedance between pins n1 and agnd is the device s network balance impedance. this node is active only when ns is at logic high. this node may be terminated when not used (i.e., ns at logic low). 21 n2 network balance node 2 (output). see n1 for description. 22 z900 line impedance 900 ? node. connects to z1 for a line impedance of 900 ? . this node should be left open circuit when not used. 23 z1 line impedance node 1 (input) . 0.1 times the times the impedance between pins z1 and z2 is the device s line impedance. this node must always be connected. 24 z2 line impedance node 2 (output). 0.1 times the times the impedance between pins z1 and z2 is the device s line impedance. this node should be left open circuit when not used. 25 tx transmit (output) . 4-wire (agnd) referenced audio output. 26 rx receive (input) . 4-wire (agnd) referenced audio input. 27 gtx0 transmit gain node 0 . connects to gtx1 for 0db transmit gain. 28 gtx1 transmit gain node 1 . a resistor to agnd provides transmit gain adjustment. 29 grx0 receive gain node 0. connects to grx1 for 0db gain. 30 grx1 receive gain node 1. a resistor to agnd provides receive gain adjustment. 31 acri ac ringing voltage input. a 1.5vrms 20hz signal is applied to this input. 32 z600 line impedance 600 ? node (output). connects to z1 for a line impedance of 600 ? . this pin should be left open circuit when not used. 33 ns network balance setting (input). the logic level at ns selects the network balance impedance. a logic 0 enables an internal balance equivalent to the input impedance (z in ). while a logic 1 enables an external balance 0.1 times the impedance between pins n1 and agnd balanced to 0.1 times the impedance between pins n1 and n2. the impedance between n1 and n2 must be equivalent to 10 times the input impedance (z in ). 34 shk off-hook indication (output). a logic low output indicates when the subscriber equipment has gone off-hook. 35 ud unbalance detect (output). a log ic low output indicates when the dc current ?w in the tip and ring leads is unbalanced, indicating that the subscriber equipment has grounded the ring lead. 36,37,38 ic internal connection. these pins are internally connected and must be left open 39 vee negative supply voltage. -5v dc. 40 vdd positive supply voltage. +5v dc. pin description (continued) pin # name description MH88628 preliminary information 4 absolute maximum ratings* * exceeding these values may cause permanent damage. functional operation under these conditions is not implied. recommended operating conditions * typical ?ures are at 25 c with nominal + 5v supplies for design aid only. dc electrical characteristics dc electrical characteristics are over recommended operating conditions unless otherwise stated. * typical ?ures are at 25 c with nominal + 5v supplies and are for design aid only. parameter sym min max units comments 1 supply voltage v bat v dd v ee v dcri +0.3 -0.3 +0.3 -0.3 65 6 -6 140 v v v v with respect lgnd 2 storage temperature t s -40 +125 c parameter sym min typ* max units comments 1 supply voltage v bat v dd v ee -44 4.75 -4.75 -48 +5.0 -5.0 -60 5.25 -5.25 v v v 2 operating temperature t op 02070 c 3 ac ring generator voltage frequency 17 90 33 vrms hz 4 dcri input dc voltage v dcri 110 120 130 vdc characteristics sym min typ* max units test conditions 1 operating loop current var in loop current from nominal i loop i loop i loop i loop 16 45 30 2 ma ma ma ma r loop =0 ? 2300 ? vbat =-48v r loop =0 ? , lca -gnd 2 operating currents i bat i bat i dd i ee 32 2 25 25 ma ma ma ma r loop =0 (off hook), lca=gnd r loop = open (on- hook) on-hook or off-hook on-hook or off- hook 3 power dissipation pd o pd 1 2 300 w mw active standby/idle 4 shk ud low level output voltage high level output voltage v ol v oh 3.7 0.5 v v i ol = 400 a i oh = 40 a 5 sel1 sel2 ese ns low level input voltage high level input voltage v il v ih 2.4 0.8 v v 6 high level input current low level input current i ih i il 20 20 a a v ih =5.0v v il =0.0v preliminary information MH88628 5 ac electrical characteristics ? * typical ?ure are at 25 c with nominal + 5v supplies and are for design aid only. ac electrical characteristics are over recommended operating conditions unless otherwise stated. notes: impedance set by external network of 600 ? or 900 ? default. external network for test purposes consists of 2200 ? + 8200 ? // 11.5nf between pins z1 and z2, the equivalent zin has 1/10 th the impedance and is equivalent o 220 ? +820 ? // 115nf. test condition uses a zin value of 600 ? , 900 ? and the above external network. test conditions use a transmit and receive gain set to 0db default and a zin value of 600 ? unless otherwise stated. ?ef indicates reference impedance which is equivalent to the termination impedance. ?et indicates network balance impedance. refer to table 1, 2 for tx, rx gain adjustment. characteristics sym min typ* max units test conditions 1 tx gain 0 db e xternally adjustable 2 rx gain 0 db e xternally adjustable 3 ringing capability 5 ren 4 on-hook transmission signal input level gain 6 2.0 v rms db v bat =-48v t-r load = 10k ? min. 5 external signal output level 1.75 2.25 v rms v bat = -48v, t-r load= 200 ? lca=0v, zo-600 ? , gain=0db 6 shk rise time fall time t r t f 1 1 ms ms dial pulse detection 7 2-wire termination impedance 600/ 900 ? selectable 8 off-hook detect threshold 10 ma 9 2-wire return loss 20 20 20 db db db 300 to 500hz 500 to 2500hz 2500 to 3400hz 10 longitudinal balance longitundinal to metallic 58 53 db db 200-1000hz 1khz - 3k4hz 11 longitudinal current capability 40 ma 20ma per lead 12 idle channel noise rx to t-r t-r to tx n cr n cx 8 12 dbrnc dbrnc 13 transhybrid loss thl 22 40 db 200-3400hz 14 unbalanced detect threshold i ub 10 ma 15 analog signal overload level at tip and ring 4 dbm t-r=600 ? , v bat =-48v 16 ringing signal voltage 90 vrms 17 ringing frequency 17 33 hz 18 ring trip delay 100 ms 19 absolute gain, variation + 0.1 db 0db at t-r, 1khz 20 relative gain, reference to 1khz + 0.05 db 300-3400hz 21 power supply rejection ratio v bat v dd v ee psrr 24 24 24 db 1khz, 100mvpp MH88628 preliminary information 6 functional description the slic uses a transformerless electronic 2-wire to 4-wire conversion which can be connected to a codec to interface the 2 wire subscriber loops to a time division multiplexed (tdm) pulse code modulated (pcm) digital switching network. for analog applications, the tx and rx of the 2-4 wire converter can be connected directly to an analog crosspoint switch such as the mt8816. powering of the line is provided through precision battery feed resistors. the MH88628 also contains control, signalling and status circuitry which combines to provide a complete functional solution which simpli?s the manufacture of line cards. this circuitry is illustrated in the functional block diagram in fig. 1. the MH88628 is designed to be pin compatible with zarlink s mh88632 and mh88625. this allows a common pcb design with common gain, input impedance and network balance. approvals fcc part 68, ccitt, doc cs-03, ul 1459, can/ csa 22.2 no.225-m90 and ansi/eia/tia-464-a are system level safety standards and performance requirements. as a component of a system, the MH88628 is designed to comply with the applicable requirements of these speci?ations. battery feed the loop current for the subscriber equipment is sourced through a pair of matched 200 ? resistors connected to the tip and ring. the two wire loop is biased such that the ring lead is 2v above vbat (typically -46v) and the tip lead is 2v below lpgd (typically -2v) during constant voltage, constant current mode. the slic is designed for a nominal battery voltage of -48vdc and can provide the maximum loop current of 45ma under the condition. the MH88628 is designed to operate down to a minimum of 16ma dc, with a battery voltage of -44v. the tip and ring output drivers can operate within 2v of v bat and lgnd rails. this permits a maximum loop range of 2300 ?. loop current setting the MH88628 slic is a constant current with constant voltage fallback design. this design feature provides for long loop capability regardless of the constant current setting. refer to graph 1. the lca (loop current adjust) pin is an input to an internal resistor divider network which generates a bias voltage. the loop current is proportional to this voltage. the loop current can be set between 20 and 45ma by various connections to the lca pin as illustrated in table 5 and figure 8. the loop current during a fault condition will be limited to a safe level. primary over-current protection is inherent in the current limiting feature of the 200 ? battery feed resistors. refer to graph 1. receive and transmit audio path the audio signal of the 2-wire side is sensed differentially across the external 200 ? feed resistors and is passed on to a second differential ampli?r stage in the 2w/4w conversion block. this block sets the transmit gain on the 4-wire side and cancels signals originating from the receive input before outputting the signal. programmable transmit and receive gain transmit gain (tip-ring to tx) and receive gain (rx to tip-ring) are programmed by connecting external resistors (rrx and rrt) from grxi to agnd and from gtx1 to agnd as indicated in figure 3 and tables 1 and 2. the programmable gain range is from -12db to +6db; this wide range will accommodate any loss plan. alternatively, the default receive gain of 0db and transmit gain of 0db can be obtained by connecting grx0 to grx1 and gtx0 to gtx1. in addition, a receive gain of +6db and transmit gain of +6db can be obtained by not connecting resistors rrx and rtx. for correct gain programming, the MH88628 |