DESCRIPTION
The IDT821621 is a long haul Subscriber Line Interface Circuit. It implements the basic telephone line interface functions such as battery feeding, impedance matching, off-hook detection and ring-trip detection.
The IDT821621 allows battery feeding between −19 V and −58 V and has the capability for driving long loops. The architecture of operating the SLIC in different states according to different loop states minimizes the system power dissipation.
This long haul SLIC is pin-to-pin compatible with AMD7920. It provides a cost-effective solution for PBX and Central Office applications.

FEATURES
◆ SLIC operating states: Active, Ringing, Standby and Disconnect
◆ Low standby power consumption (35 mW)
◆ −19 V to −58 V battery operation
◆ On-hook transmission
◆ Two-wire impedance set by single external impedance
◆ Programmable constant-current feed
◆ Programmable loop-detect threshold
◆ Programmable ring-trip detect threshold
◆ +3.3 V / +5 V compatible power supply
◆ No −5 V supply required
◆ On-chip Thermal Management (TMG)
◆ Four on-chip relay drivers and relay snubbers, 1 ringing and 3 general purpose
◆ Package available: 32 pin PLCC