Intelligent Access
™
Voice Solutions
Am79R251
Intelligent Subscriber Line Interface Circuit (ISLIC
™
)
DISTINCTIVE CHARACTERISTICS
s
Monitor of two-wire interface voltages and
currents supports
— Voice transmission
— Through chip ring generation
— 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
s
Supports internal and external ringing
— High voltage operation supports long loops
s
+5 V and battery supplies
s
Dual battery operation for system power saving
— Automatic battery switching
— Intelligent thermal management
s
Compatible with inexpensive protection
networks
— Accommodates low tolerance fuse resistors or
PTC thermistors
s
Metering capable
— 12 kHz and 16 kHz
— Smooth polarity reversal
s
Tip-open state supports ground start signaling
s
Integrated test load switches/relay drivers
BLOCK DIAGRAM
RSN
AD
SA
HPA
HPB
SB
BD
Attenuator
VSAB
Two-Wire
Interface
Longitudinal
Control
Gain/Level Shift
Signal
Transmission
VTX
VLB
VREF
Signal
Conditioning
IMT
ILG
TMN
TMP
TMS
VBP
VBL
Thermal
Management
Control
Fault
Meas
CREF
Switch
Driver
VBH
R2
R3
RYE
Relay
Drivers
Relay Control
P1
Input Decoder and
Control Registers
P2
P3
LD
R1
Relay
Driver 1
BGND
GND
VCC
Pub. #
22480
Rev:
C
Amendment:
/0
Issue Date:
December 1999
AMD [ ADVANCED MICRO DEVICES ]
