DS2176

Telecom Overview

The DS2176 is a low-power CMOS T1 receive buffer designed to synchronize loop-timed T-carrier data streams with system-side timing. It features a two-frame (386-bit) PCM buffer that samples incoming serial data on the falling edge of RCLK and outputs it on the rising edge of SYSCLK. The device supports both 1.544 MHz and 2.048 MHz backplane frequencies via the SCLKSEL pin. It extracts, buffers, and integrates ABCD robbed-bit signaling, presenting it on dedicated outputs A through D. The component operates at a supply voltage of 5.0V with a typical current draw of 10mA.

Telecom Feature Summary

• Synchronizes received T1 PCM data to host backplane frequencies using a two-frame buffer depth.
• Extracts and supervises robbed-bit signaling data embedded in the stream for ABCD channels.
• Freezes signaling updates during alarm or slip conditions to maintain data integrity.
• Integrates signaling data over multiple multiframes to minimize corruption from random noise hits.

Telecom Applications

• Digital trunk interfaces
• Drop and insert equipment
• Transcoders and digital cross-connects (DACs)
• Private network equipment
• PABX-to-computer interfaces

Telecom Procurement Notes

Verify the specific package variant required for the design, as the standard DS2176 uses a 24-pin DIP while the surface mount version is designated DS2176Q. Confirm the operating temperature range matches the application needs, noting that industrial grades are available as DS2176N. Ensure compatibility with the intended transceiver, such as the DS2180A, before finalizing procurement specifications.

Telecom Selection Notes

Select the DS2176 when interfacing loop-timed T1 data to system-timed parallel or serial backplanes. Choose the DS2176Q for surface mount requirements or the DS2176N for extended industrial temperature ranges. Ensure the system clock frequency aligns with the SCLKSEL configuration for either 1.544 MHz or 2.048 MHz operation. Verify framing mode requirements to configure FMS correctly for D4 or extended framing.

Telecom Part Context

The DS2176 belongs to the Maxim Integrated T1/CEPT interface family, functioning specifically as a receive buffer. It complements line interface units like the DS2156L by handling the synchronization between the physical layer and the digital multiplexing backplane. This component simplifies hardware designs by integrating buffering and signaling supervision into a single package.

Telecom Replacement Considerations

The DS2176QN/T&R is a reel-and-reel packaging variant of the same functional device. No direct functional replacements are documented in the provided datasheet; however, designers should verify if newer generation T1 receivers meet the specific signaling integration and freeze requirements of this legacy component.

Telecom FAQ

How does the DS2176 handle signaling updates during a slip condition?

During a slip condition, the DS2176 freezes signaling updates to prevent corrupted data from propagating. The SIGFRZ output goes high to indicate this state, and 'old' data is recirculated in the output registers until the next valid update occurs.

What is the function of the ALN pin?

The ALN (Align) pin forces the buffer to recenter on the next system side frame boundary. This is typically used during power-up or initialization. If the buffer depth is not optimum during this process, a slip will occur.

How is the signaling integration feature configured?

Signaling integration is configured using the SM0 and SM1 pins. These pins select the degree of integration (e.g., bypass, 2 multiframes, or 5 multiframes) and determine how many multiframes the signaling data must remain stable before appearing at the outputs.