MH88634

® MH88634 Central Office Interface Circuit Preliminary Information Features Loop Start Trunk Interface 600 ohm input impedance, -2 variant Line state detection outputs: forward loop, reverse loop, ringing voltage, switch hook On-hook reception Transformerless 2W to 4W conversion One loop start relay driver +/- 5V operation Small footprint area (<4.75cm 2) MH88634-2 ISSUE 2 April 1995 Ordering Information 21 Pin SIL Package 0° C to 70° C Description The Mitel MH88634 Central Office Trunk Interface circuit provides a complete audio and signalling link between audio switching equipment and a central office. The functions provided by the MH88634 include 2-4 Wire conversion, 600 ohm input impedance and network balance. The device is fabricated as a thick film hybrid incorporating various technologies for optimum circuit design and very high reliability. Applications Interface to Central Office for: PABX Key Telephone Systems Channel Bank Voice Mail Terminal Equipment Digital Loop Carrier Optical Multiplexer RING TIP VDD VEE AGND RV FL RL SHK Dummy Ringer Status Detection XLA XLB XLC XLD LRC LRD Loop Termination 2-4 Wire Hybrid Loop Relay Driver Impedance Matching Network Balance Receive Gain Rx Transmit Gain Tx VRLY RGND Figure 1 - Functional Block Diagram 2-253 MH88634 TIP RING XLA XLD XLB XLC IC IC IC SHK Rx VEE Tx RV FL RL VDD AGND LRC VRLY LRD 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Preliminary Information ...