4 x 4 16 Channel T1 Framer / 4 x 3 12 Channel T1 Framer

Please check latest availability status for a specific part variant.


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.

All of the functions available on the DS21Q42 are also available in the MCM packaged version. However, in order to minimize package size, some signals have been deleted or combined. These differences are detailed in Table 1-1. In the 4 x 3 (FT) version, the fourth quad framer is not populated and hence all of the signals to and from this fourth framer are absent and should be treated as No Connects (NC). Table 2-1 lists all of the signals on the MCM and it also lists the absent signals for the 4 x 3.

The availability of both a 12-channel and a 16-channel version allow the maximum framer density with the lowest cost. For example, in a T3 application, two devices (one DS21FF42 and one DS21FT42) provide 28 framers without the additional cost and power consumption of any unused framers that appear in an octal approach.
DS21FF42, DS21FT42: Functional Diagram DS21FF42, DS21FT42: Functional Diagram Enlarge+

Key Features

  • 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


  • High-Density Line Cards
  • Multiplexers/Demultiplexers
  • Routers/Switches
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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