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