Document ID# 081195 Date: Sep 19, 2007
Rev: E Version: 2
Distribution: Public Document
NOTE: On August 3, 2007, Zarlink Semiconductor acquired the products and
technology of Legerity Holdings.
™
Le7942B
Subscriber Line Interface Circuit
VE580 Series
DISTINCTIVE CHARACTERISTICS
Programmable constant-current feed
Receive current gain = 500
Programmable loop-detect threshold
Low standby power
Performs polarity reversal
Ground-key detector
Pin for external ground-key noise filter capacitor
Test relay driver option
Compatible with Le7942 Device
Tip Open state for ground-start lines
–19 V to –58 V battery operation
Ideal for PBX and KTS applications
On-chip switching regulator for low-power
dissipation
Can be used with or without the on-chip switching
regulator
On-hook transmission
BLOCK DIAGRAM
VTX
VREG
VBAT
15474A-001
Signal
Transmission
Input Decoder
and Control
Ground-Key
Detector
Ring Relay Driver
Test Relay Driver
C1
C2
C3
C4
E1
GKFIL
RSN
Off-Hook
Detector
Power-Feed
Controller
Ring-Trip
Detector
Switching
Regulator
TESTOUT
RINGOUT
RD
RDC
L
Two-Wire
A(TIP)
HPA
HPB
B(RING)
BGND
DA
DB
CHS CHCLK
VCC VEE
AGND/DGND
CAS
DET
QBAT
Interface
A Voice Solution
