Notes:
1. Am79534—E0 and E1 inputs; ring and test relay drivers sourced internally to BGND.
2. Am79535—E0 and E1 inputs; ring relay driver sourced internally to BGND; ground-key filter pin.
3. Current gain (K
1
) = 1000 for all parts.
Am79534/Am79535
Subscriber Line Interface Circuit
DISTINCTIVE CHARACTERISTICS
a73 Programmable constant-current feed
a73 Line-feed characteristics independent of
battery variations
a73 Programmable loop-detect threshold
a73 On-chip switching regulator for low-power
dissipation
a73 Pin for external ground-key noise-filter
capacitor available
a73 Ground-key detect
a73 Two-wire impedance set by single external
impedance
a73 Polarity reversal feature
a73 Tip Open state for ground-start lines
a73 Test relay driver optional
a73 On-hook transmission
BLOCK DIAGRAM
Two-Wire
Interface
HPA
HPB
DA
DB
BGND
VBAT
A(TIP)
B(RING)
Ground-Key
Detector
Signal Transmission
Power-Feed
Controller
Ring-Trip Detector
VCC VEE AGND
RINGOUT
C1
C2
E1
E0
DET
RSN
VTX
RD
RDC
Ring Relay Driver
Input Decoder
and Control
Off-Hook Detector
Test Relay Driver TESTOUT
C3
C4
GKFIL
Switching Regulator
VREG
L
CHS QBAT CHCLK
16854C-01
Publication# 16854 Rev: D Amendment: /0
Issue Date: October 1999