Am79574
Subscriber Line Interface Circuit
DISTINCTIVE CHARACTERISTICS
s
Programmable constant resistance 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 option available
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
(TIP)
A
Ring Relay Driver
Test Relay Driver
RINGOUT
TESTOUT
C1
C2
C3
C4
E1
E0
DET
GKFIL
VTX
RSN
HPA
Ground-Key
Detector
Input Decoder
and Control
Two-Wire
Interface
HPB
Signal
Transmission
B(RING)
Power-Feed
Controller
DA
DB
VREG
L
VBAT
BGND
Off-Hook
Detector
RD
RDC
Ring-Trip Detector
Switching
Regulator
CHS QBAT CHCLK
VCC
VEE AGND
16855C-001
Notes:
1. Am79574—E0 and E1 inputs; ring and test relay drivers sourced internally to BGND.
2. Output amplifier current gain (K
1
) = 1000.
Publication#
16855
Rev:
E
Amendment: /0
Issue Date:
October 1999
AMD [ ADVANCED MICRO DEVICES ]
