View ds21q352 datasheet:

DALLAS SEMICONDUCTOR Preliminary Quad T1/E1 Transceiver (5V) DS21Q552/DS21Q554 Quad T1/E1 Transceiver (3.3V) DS21Q352/DS21Q354 FEATURES P • Four (4) Completely Independent T1 or E1 Transceivers In One Small 27mm x 27mm Package • Each Transceiver Contains a Short & Long Haul Line Interface Plus a Full Featured Framer with Alarm Detection/Generation, Elastic Stores, Hardware Based Signaling Support, Per DS0 Channel Control and HDLC Controller • Each Multi-Chip Module (MCM) Contains Four Die of: DS21352 (DS21Q352) DS21552 (DS21Q552) DS21354 (DS21Q354) DS21554 (DS21Q554) • Selection Guide: Supply Device T1 3.3V DS21Q352 T1 5V DS21Q552 E1 3.3V DS21Q354 E1 5V DS21Q554 • See the Specific DS21352/DS21552 and DS21354/DS21554 Data Sheets for Details on their Feature Set and Op