Am7945
Subscriber Line Interface Circuit
DISTINCTIVE CHARACTERISTICS
s
Programmable constant-current feed
s
Current gain = 200
s
Programmable loop-detect threshold
s
Low power Standby state
s
Ground-key detector
s
Tip Open state for ground-start lines
s
–19 V to –56.5 V battery operation
s
On-chip Thermal Management (TMG) feature
s
Two-wire impedance set by single external
impedance
s
On-hook transmission
s
On-chip ring relay driver and relay snubber
circuit
s
Ideal for low cost PABX and key telephone
systems
BLOCK DIAGRAM
TMG
A(TIP)
Ring Relay
Driver
RINGOUT
C1
C2
HPA
Two-Wire
Interface
HPB
Signal
Transmission
B(RING)
Off-Hook
Detector
Ground-Key
Detector
Input Decoder
and Control
C3
E0
E1
DET
RSN
VTX
RD
Power-Feed
Controller
DA
DB
VBAT
BGND
Ring-Trip
Detector
RDC
CAS
VCC
VEE
AGND/DGND
Publication#
18408
Rev:
D
Amendment:
/0
Issue Date:
October 1999
AMD [ ADVANCED MICRO DEVICES ]
