1 t r a n s f o r m e r l e s s 2 - w i r e t o 4 - w i r e c o n v e r s i o n b a t t e r y a n d r i n g i n g f e e d t o l i n e . o f f - h o o k a n d d i a l p u l s e d e t e c t i o n . r i n g g r o u n d o v e r - c u r r e n t p r o t e c t i o n . c o n s t a n t c u r r e n t f e e d w i t h c o n s t a n t v o l t a g e f o l d o v e r . r e l a y d r i v e r . p o w e r d e n i a l . w i d e o p e r a t i n g r a n g e . p i n f o r p i n c o m p a t i b l e 6 0 0 r a n d 9 0 0 r v a r i a n t s . a p p l i c a t i o n s l i n e i n t e r f a c e f o r : p a b x i n t e r c o m s k e y t e l e p h o n e s y s t e m s c o n t r o l s y s t e m s d e s c r i p t i o n t h e s l i c p r o v i d e s a c o m p l e t e i n t e r f a c e b e t w e e n a s w i t c h i n g s y s t e m a n d a s u b s c r i b e r l o o p . f u n c t i o n s p r o v i d e d i n c l u d e b a t t e r y f e e d a n d r i n g i n g f e e d t o t h e s u b s c r i b e r l i n e , 2 - w i r e t o 4 - w i r e h y b r i d i n t e r f a c i n g , c o n s t a n t c u r r e n t f e e d w i t h c o n s t a n t v o l t a g e f o l d b a c k , a n d d i a l p u l s e d e t e c t i o n . t h e d e v i c e i s f a b r i c a t e d u s i n g t h i c k l m h y b r i d t e c h n o l o g y i n a 2 0 - p i n s i n g l e i n - l i n e p a c k a g e . f i g u r e 1 - f u n c t i o n a l b l o c k d i a g r a m c u r r e n t a n d v o l t a g e s e n s i n g r e l a y d r i v e c i r c u i t c o n s t a n t c u r r e n t f e e d o v e r c u r r e n t p r o t e c t i o n 2 - w i r e t o 4 - w i r e c o n v e r s i o n l o o p s u p e r v i s i o n p o w e r c o n s t a n t m a n a g e m e n t v o l t a g e f o l d b a c k t f t i p r i n g r f r v v r l y r c r d c d l p g n d v b a t p d v c c v e e a g n d v r v x c a p s h k o r d e r i n g i n f o r m a t i o n m h 8 8 6 1 2 b v - k 2 0 p i n s i l p a c k a g e ( 6 0 0 r ) m h 8 8 6 1 2 b v - 4 k 2 0 p i n s i l p a c k a g e ( 9 0 0 r ) 0 c t o 7 0 c m h 8 8 6 1 2 b v - k s u b s c r i b e r l i n e i n t e r f a c e c i r c u i t ( s l i c ) a d v a n c e i n f o r m a t i o n d s 5 0 6 6 i s s u e 2 j a n u a r y 1 9 9 9
MH88612BV-K advance information 2 figure 2 - pin connections note 1: c4 in figure 3 can be added permanently to this pin for certain dial pulse applications. pin description pin # name description 1tf tip feed. connects to external diode for protection 2 lpgnd loop ground . is the system ground reference with respect to v b at. normally connected to agnd. 3vr voice receive (input). the 4 wire analog signal to the device. 4ic internal connection. no connection should be made to this pin 5 vee negative power supply voltage (-5v). 6 agnd analog ground. connects to system ground (earth). 7pd power denial (input) . a logic high will isolate the battery voltage to tip/ring. 8vx voice transmit (output) . the 4-wire analog signal from the device. 9 tip tip lead . connects to the "tip" lead of the telephone line. 10 ring ring lead. connects to the "ring" lead of the telephone line. 11 rf ring feed (input). normally connected to ring relay for negative battery feed voltage and ringing voltage input. 12 vcc positive power supply voltage (+5v). 13 rc relay control (input) . active high. 14 rd relay drive. open collector sinks current when rc is at logic high. 15 rv ring feed voltage. normally connected to pin 11 (rf) through a normally closed relay and to external diode protection. 16 vrly relay voltage supply (+5v). 17 cd clamping diode . normally connected to agnd. 18 vbat negative battery feed supply voltage (-48v). battery supply for the subscriber line. typically -48vdc is applied to this pin. 19 cap ring trip filter capacitor. normally connected via an external capacitor to ground to prevent false ring trip. must be open circuit to allow dial pulse detection. 20 shk switch hook detect (output). a logic level 1 will indicate that the subscriber line is in the off-hook state. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 tf lpgnd vr ic vee agnd pd vx tip ring rf vcc rc rd rv vrly cd vbat cap shk
advance information MH88612BV-K 3 functional description the slic performs a transformerless 2-wire to 4- wire conversion of the analog signal. the 2-wire circuit is the balanced line going to the subscriber loop, while the 4-wire circuit is the audio signal going to and from devices such as the voice codec or switching circuit. the slic also provides a switch hook (shk) status output which goes high when the telephone is set off-hook. constant current feed the MH88612BV-K family employs complex feedback circuits to supply a constant current feed or, if necessary, constant voltage feed to the line. with a nominal -48v battery the device will supply a constant current of typically 25ma to a line up to 1100 w . for longer lines there is insuf?cient battery voltage so the device automatically switches to constant voltage mode where tip and ring will stay at their minimum and maximum voltage levels and the supplied current will be reduced accordingly. the maximum line resistance supported is 2000 w including the telephone set. switch hook detection the shk pin will go to logic 1 to indicate that a telephone connected to the line has gone off-hook (on-line). off-hook will not be indicated if the loop resistance (including the telephone set) is too high for the device to support. the shk output will toggle to indicate dial pulses on the line. if the capacitor on cap (pin 19) has not been switched out of circuit the dial pulses will be distorted. ringing and ring trip detection in figure 3 a ringing signal (e.g.90 vrms and -48vdc) is applied to the line by disconnecting pin 15 (rv) from pin 11(rf), and connecting the ringing voltage at pin 11 (rf) by use of the relay k1. the slic can detect an off-hook condition during ringing but there is a large ac component which must be ?ltered out to give a true off-hook condition at shk. a 1.0 m f capacitor connected from pin 19 (cap) to ground will provide adequate attenuation when ringing is applied. once an off-hook condition has been detected a logic low should be applied to pin 13 (rc) which will deactivate the relay (k1) to disconnect the ringing voltage from pin 11 and reconnect to pin 15. at that time the slic will revert to constant current feed operation. for applications requiring dial pulse detection the capacitor connection to ground c1 should be controlled such that the capacitor is disconnected during pulse dialling. if the signalling method is unknown, a capacitor of approximately 56nf should be permanently ?tted between cap (pin 19) and ground. this should be in addition to the capacitor mentioned in the above paragraph. during off-hook conditions (on-line), the capacitor (c1) should not have a low impedance path to ground. this can be achieved using a transistor (q1) and resistor (r2) as shown in figure 3, with r2 providing a high impedance path for c1. when ringing is applied (rc = 5v) the transistor will short circuit r2 which will give c1 a low impedance path to ground and provide the required ?ltering. other methods can be used to switch out c1, such as a relay or a codec system drive output (with a similar con?guration as above). for applications using dtmf signalling, c1 can be permanently connected to ground. current limit the tip or ring of the telephone line may accidentally be shorted to ground. in such a case, current will only ?ow through the feed resistor. this high current will be sensed and reduced by the current limit circuit to a lower value to protect the internal circuitry. power denial the power denial function is a feature of the mh88612 which allows for powering down of the subscriber loop. a logic high voltage applied to the power denial input effectively removes the battery voltage from the loop driver circuitry. the resulting i loop is negligible and power consumption is minimised. the power denial function is useful for disabling a loop which may have a ground fault.
MH88612BV-K advance information 4 . figure 3 - typical application circuit vr vx shk pd cap agnd vee vcc vbat cd rd rc vrly ring tip tf lpgnd rv rf vbat 3 8 20 7 19 c1 6 5 12 18 -5v +5v -48v 17 14 16 13 10 9 1 2 15 11 d3 d1 d2 d4 tip ring +5v k1 r1 + - MH88612BV-K k1 r2 ~ 90 vrms - + 48v component list r1 200 w + 10%, 1/4w r2 470k w + 5%, 1/4w c1 1.0 m f, + 10%, 25v electrolytic capacitor k1 relay e/m, 5v or 6v, 1 form c protection circuit c2 c3 r3, r4 10k w + 5%, 1/4w c2, c3 0.1 m f, + 20%, 50v ceramic de-coupling capacitors d1,d2, d3, d4 diode recti?er 200v, 1a, in4003 q1 general purpose switching transistor protection circuit - depending on the application the protection circuit may need to provide over-voltage and/or over-current protection. in certain circumstances no protection will be required. q1 r3 rc (pin 13) r4 c4 c4 10nf - 56nf 20% 16v capacitor = earth = ground
advance information MH88612BV-K 5 * exceeding these values may cause permanent damage. functional operation under these conditions is not implied. ?typical ?gures are at 25?c with nominal 5v supplies and are f or design aid only. ? dc electrical characteristics are over recommended operating supply voltages. ?typical ?gures are at 25?c with nominal 5v supplies and are f or design aid only. absolute maximum ratings* parameter symbol min max units 1 dc supply voltage lpgnd = agnd v cc v ee v bat v rly -0.3 -9 -60 -0.3 9 0.3 0.3 40 v v v v 2 storage temperature t s -40 100 c 3 package power dissipation pd 2 w recommended operating conditions characteristics sym min typ ? max units test conditions 1 operating supply voltage v cc v ee v bat v rly 4.75 -5.25 -54 5.0 -5.0 -48 5 5.25 -4.75 -42 v v v v 2 relay driver current i rly 100 ma 3 t o 070 c dc electrical characteristics ? - voltages are with respect to gnda unless otherwise stated. characteristics sym min typ ? max units test conditions 1 supply current v cc v ee v bat i cc i ee i bat 7.5 -5.1 3 800 ma ma m a ma pd = logic high pd = logic low, idle 2 power consumption p c 160 1600 mw mw standby v bat = -48v active (off hook) 3 constant current line feed i loop 23 15 25 16.5 27 19 ma ma r loop <1100 w r loop 2000 w v bat = -48v 4 operating loop resistance r loop 2000 w v bat = -48v @ i loop = 16ma, r loop includes telephone set 5 ring ground over-current protection 45 ma v bat = 48v 6 off-hook detect output low voltage (on-hook) output high voltage (off-hook) v ol v oh 2.7 0.4 v v active high logic i ol = 8ma i ol = -100ma 7 rc, pd control input input low volt (no activation) input high volt (activation) v il v ih 2.0 0.7 v v active high logic lsttl compatible 8 rc, pd control input input low current (no activation) input high current (activation) i il i ih 50 0.5 m a ma 9 pd control input input low current input high current i il i ih 0.5 0.3 ma ma
MH88612BV-K advance information 6 ?typical ?gure are at 25 c and are for design aid only. ac electrical characteristics characteristics sym min typ ? max units test conditions 1 ringing voltage frequency v ring f ring 17 90 25 v rms hz superimposed on v bat = -48v 2 ringer equivalence number ren 2 3 ring trip detect time 200 300 ms 4 input ac impedance 2-wire zin 600 900 w w MH88612BV-K mh88612bv-4k 5 input impedance at vr 100 k w 6 output impedance at vx 10 w 7 gain 2-wire to vx gain relative to gain @ 1khz -1.3 -0.3 -1.0 -0.7 +0.3 db input + 3dbm, 1khz across tip and ring 300-3400 hz 8 gain vr to 2-wire gain relative to gain @ 1khz -1.3 -0.3 -1.0 -0.7 +0.3 db db input 0.5vrms 1khz at vr z load = 600 w 300 - 3400 hz 9 2-wire return loss over 300-3400hz 20 30 db input 0.5vrms, 1khz across tip and ring z load = 600 w 10 transhybrid loss thl 20 30 db 300-3400 hz z load = 600 w 11 longitudinal to metallic balance 40 46 55 55 db db 300-600hz 600-3400hz 12 total harmonic distortion at vx at tip and ring thd 0.1 0.1 1.0 1.0 % % input + 3dbm, 1khz across tip and ring input 1.0vrms 1khz at vr 13 common mode rejection ratio 2-wire to vx cmrr 40 50 db input 0.5vrms, 1khz 14 idle channel noise nc +14 dbrnc @ 2 wire and vx c- message weighted 15 power supply rejection ratio v cc v ee v bat psrr 26 26 26 db db db 100 mv pp ripple, 1khz on v cc /v ee /v bat , measure at vx and across tip and ring
advance information MH88612BV-K 7 figure 4 - mechanical data 1 0.50 max (12.70 max) 0.02 + 0.005 (0.51 + 0.13) 0.10 + 0.01 (1.27 + 0.51) 0.05 + 0.02 0.18 + 0.02 (4.57 + 0.51) (2.54 + 0.25) * * 0.12 max (3.05 max) 0.01 + 0.002 (0.25 + 0.05) 0.08 max (2.03 max) 2.02 max (51.30 max) notes: 1) not to scale 2) dimensions in inches. (dimensions in millimetres) * dimensions to centre of pin. 3) pin tolerances are non-accumulative. 4) recommended soldering conditions: wave soldering max. temp: 260?c for 10 secs.
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