MULTI-CHIP MODULE (MCM) DESCRIPTION
The Four x Four and Four x Three MCMs 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 a Multi-Chip Module (MCM) with the electrical connections as shown in Figure 1-1.

FEATURES
• Sixteen (16) or Twelve (12) Completely Independent T1 Framers in One Small 27mm x 27mm Package
• Each Multi-Chip 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 BGA package (27mm X 27mm)
• Low Power 3.3V CMOS with 5V Tolerant Input & Outputs