MULTICHIP MODULE DESCRIPTION
The 4 x 4 and 4 x 3 multichip modules (MCM) offer a high-density packaging arrangement for the DS21Q42 T1 Enhanced Quad Framer. Either three (DS21FT42) or four (DS21FF42) silicon die of these devices is packaged in an MCM with the electrical connections as shown in Figure 1-1.

FEATURESP
■ 16 or 12 completely independent T1 framers in one small 27mm x 27mm, 1.27mm pitch BGA package
■ Each multichip module (MCM) contains four (FF) or three (FT) DS21Q42 die
■ Each quad framer can be concatenated into a single 8.192MHz backplane data stream
■ IEEE 1149.1 JTAG-Boundary Scan Architecture
■ DS21FF42 and DS21FT42 are pin compatible with DS21FF44 and DS21FT44, respectively, to allow the same footprint to support T1 and E1 applications
■ 300-pin MCM 1.27mm pitch BGA package (27mm x 27mm)
■ Low-power 3.3V CMOS with 5V tolerant input and outputs

APPLICATIONS
■ DSLAMs
■ Multiplexers/Demultiplexers
■ Switches
■ High-Density Line Cards