DS21455+

Telecom Overview

The DS21455+ is a quad monolithic T1/E1/J1 transceiver manufactured by Analog Devices Inc./Maxim Integrated. It integrates four independent transceivers, each comprising a line interface unit (LIU), framer, HDLC controllers, and a TDM backplane interface. The device operates on a single 3.3V supply with 5V tolerant I/O and features an 8-bit parallel control port compatible with Intel or Motorola bus protocols. It supports software-selectable operation for T1, E1, and J1 standards within a 256-pin BGA package measuring 27mm x 27mm. Operating temperatures range from -40°C to +85°C for the DS21455N+ variant.

Telecom Feature Summary

• Integrates four fully independent transceivers capable of software configuration for T1, E1, or J1 network interfaces.
• Includes crystal-less jitter attenuators and dual two-frame elastic-store slip buffers for asynchronous backplane connections up to 16.384MHz.
• Features internal programmable termination resistors for 75Ω, 100Ω, and 120Ω T1 and E1 interfaces alongside CMI coder/decoder capabilities.
• Supports IEEE 1149.1 JTAG boundary scan and provides dual HDLC controllers per channel for enhanced protocol handling.

Telecom Applications

• Routers
• Channel Service Units (CSUs)
• Data Service Units (DSUs)
• Multiplexers (Muxes)
• T1/E1 Test Equipment

Telecom Procurement Notes

Verify component authenticity through authorized distributors or direct manufacturer channels. Confirm RoHS compliance status and lead-free packaging specifications prior to integration. Ensure proper handling procedures are followed due to moisture sensitivity classification. Validate that the specific suffix matches the required temperature range and pinout configuration for the target application design.

Telecom Selection Notes

Select the DS21455+ when a quad-channel solution replacing legacy DS21Q55 modules is required. Choose the N+ suffix variant for extended industrial temperature ranges (-40°C to +85°C). Ensure the host processor supports the necessary 8-bit parallel interface timing for Intel or Motorola modes. Verify board space constraints accommodate the 256-pin BGA footprint during the layout phase.

Telecom Part Context

This component belongs to the Maxim Integrated DS2145x family of quad transceivers. It serves as a direct replacement for the older DS21Q55 quad MCM device while offering improved controller interface performance. The DS21458 shares software compatibility but utilizes a smaller CSBGA package. Both variants support Signaling System 7 and AIS-CI/RAI-CI generation.

Telecom Replacement Considerations

The DS21455+ is documented as a direct replacement for the DS21Q55. Designers should account for the architectural difference where the DS21455 uses a single JTAG controller for all four transceivers, unlike the per-transceiver architecture of the DS21Q55.