DS21Q42TN

Telecom Overview

The DS21Q42TN is an enhanced quad T1 framer manufactured by Analog Devices Inc./Maxim Integrated. It integrates four fully independent framing transceivers supporting T1, DS1, ISDN-PRI, and J1 standards. The device features dual two-frame elastic store slip buffers per framer for asynchronous backplane connections up to 8.192 MHz. It includes an integral HDLC controller with 64-byte buffers configurable for FDL or DS0 operation. The unit operates on a 3.3V supply with 5V tolerant I/O and is housed in a 128-pin TQFP package. The TN suffix indicates an extended operating temperature range of -40°C to +85°C.

Telecom Feature Summary

• Four fully independent T1 framing transceivers with separate transmit and receive functionality
• Integral HDLC controller with 64-byte buffers for FDL or DS0 configuration
• Supports D4, ESF, and SLC-96 multiframe formats with programmable output clocks
• IEEE 1149.1 JTAG boundary scan support for test access

Telecom Applications

• T1 line interface units (LIUs)
• Channel service units (CSUs)
• Digital signal cross-connect systems
• Fractional T1 multiplexers

Telecom Procurement Notes

Verify the specific ordering suffix against current manufacturer documentation to confirm the temperature grade and package type. Confirm availability status as legacy components may have limited production runs. Ensure compatibility with existing system voltage levels and bus protocols before integration.

Telecom Selection Notes

Select this component when multiple independent T1 framing channels are required within a single integrated circuit. The device supports both Intel and Motorola bus interfaces via its parallel control port. Consider the pin compatibility with the DS21Q44 if E1 functionality is also needed in similar designs.

Telecom Part Context

The DS21Q42 series represents an evolution of the DS21Q41B quad T1 framer, adding hardware signaling capabilities and full HDLC controllers. The DS21Q42TN specifically denotes the industrial temperature variant (-40°C to +85°C) packaged in a 128-pin Thin Quad Flat Package (TQFP).

Telecom Replacement Considerations

The DS21Q42T is the commercial temperature version of this device. The DS21Q44 is a pin-compatible enhanced quad E1 framer.