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Pub. # 080248
Rev: C
Amendment: /0
Issue Date: December 1999
Intelligent Access
ä Voice Solutions
DISTINCTIVE CHARACTERISTICS
Monitor of two-wire interface voltages and
currents supports
— Voice transmission
— Programmable DC feed characteristics
— Independent of battery
— Current limited
— Selectable off-hook and ground-key thresholds
— Subscriber line diagnostics
— Leakage resistance
— Loop resistance
— Line capacitance
— Bell capacitance
— Foreign voltage sensing
— Power cross and fault detection
+5 V and battery supplies
Dual battery operation for system power saving
— Automatic battery switching
— Intelligent thermal management
Compatible with inexpensive protection
networks
— Accommodates low tolerance fuse resistors or
PTC thermistors
Metering capable
— 12 kHz and 16 kHz
— Smooth polarity reversal
Tip-open state supports ground start signaling
Ring relay driver for external ringing
Integrated test load switches/relay drivers
BLOCK DIAGRAM
Two-Wire
Interface
AD
SA
BD
SB
HPB
HPA
TMN
TMP
VBL
VBH
R2
R3
RYE
R1
BGND
VCC
GND
LD
P3
P2
P1
IMT
ILG
VREF
VSAB
VLB
VTX
RSN
Signal
Transmission
Gain/Level Shift
Longitudinal
Control
Attenuator
Thermal
Management
Control
Fault
Meas.
Signal
Conditioning
Switch
Driver
Relay
Drivers
Relay
Driver 1
Input Decoder and
Control Registers
Relay Control
TMS
CREF
Am79231
Intelligent Subscriber Line Interface Circuit (ISLIC™)
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