™
Le7920
Subscriber Line Interface Circuit
VE580 Series
The Le7920 Subscriber Line Interface Circuit implements the
basic telephone line interface functions, and enables the
design of low cost, high performance, POTS line interface
cards.
DISTINCTIVE CHARACTERISTICS
Control states: Active, Ringing, Standby,
and Disconnect
Low standby power (35 mW)
–19 V to –58 V battery operation
On-hook transmission
Two-wire impedance set by single external
impedance
Programmable constant-current feed
Programmable loop-detect threshold
Programmable ring-trip detect threshold
No –5 V supply required
Current Gain = 500
On-chip Thermal Management (TMG) feature
Four on-chip relay drivers and relay snubbers, 1
ringing and 3 general purpose (32 PLCC)
BLOCK DIAGRAM
TMG
Relay
Driver
Relay
Driver
Relay
Driver
A(TIP)
Ring Relay
Driver
RYOUT3
RYOUT2
RYOUT1
RINGOUT
D1
D2
D3
C1
C2
DET
HPA
Input Decoder
and Control
Two-Wire
Interface
HPB
B(RING)
Signal
Transmission
Off-Hook
Detector
Power-Feed
Controller
VTX
RSN
RD
RDC
CAS
Ring-Trip
Detector
DA
DB
VBAT
BGND
VCC
VBREF
AGND/DGND
Document ID#
080146
Date:
Rev:
J
Version:
Distribution:
Public Document
Sep 19, 2007
2
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
