Analog Devices Inc./Maxim Integrated DS2176Q

Overview

DS2176Q from Maxim Integrated (now part of Analog Devices) is a low-power CMOS T1 receive buffer IC designed to synchronize loop-timed T1 PCM data streams (1.544 MHz) to system-side timing while extracting and supervising robbed-bit ABCD signaling. It features a 2-frame (386-bit) buffer, slip-compensated multiframe sync (SMSYNC), open-collector SLIP output active low for 65 SYSCLK cycles, and supports both 193S and 193E framing modes. It is used in digital cross-connects, PABX-to-computer interfaces, and transcoders.

For engineers reviewing the DS2176Q datasheet, DS2176Q pinout, DS2176Q application, or DS2176Q equivalent, key selection considerations include its 24-pin 300-mil DIP surface-mount package, dual-clock compatibility (1.544/2.048 MHz via SCLKSEL), signaling freeze control (SIGFRZ), and frame-boundary slip behavior with external recentering (ALN).

Technical Context

The DS2176Q implements a dual-clock domain architecture: RCLK (1.544 MHz) samples RSER on its falling edge, while SYSCLK (1.544 or 2.048 MHz) controls SSER, A/B/C/D, SMSYNC, and SLIP outputs on its rising edge. Buffer depth is monitored in real time via RMSYNC–SMSYNC phase relationship, enabling slip detection before overflow/underflow.

Signaling supervision uses configurable integration (SM0/SM1) and freeze logic: updates occur once per multiframe at SMSYNC rising edge unless inhibited by ALN, SIGH, or slip condition; SIGFRZ asserts high during freeze, and C/D outputs mirror prior multiframe A/B data in 193S mode.

Key Specifications

Pinout & Package

DS2176Q is housed in a 24-pin, 300-mil wide plastic DIP surface-mount package (JEDEC MS-001AC), with 0.300" × 0.600" footprint and 0.100" lead pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar T1 receive buffer and signaling supervision applications.

Compared with DS2175Q and MC145508P, the DS2176Q uniquely integrates 2-frame slip compensation, programmable signaling integration/freeze, and dual-clock-rate support in a single 24-pin package-reducing design complexity for T1 receive-side timing and signaling applications.

Availability

DS2176Q is available at Aetrix Electronics and suitable for digital cross-connect systems, PABX-to-computer interfaces, and T1 line card designs requiring stable component supply, long-term lifecycle support, and verified telecom-grade performance.

Supply support for DS2176Q includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (acquired by Analog Devices in 2021) is a U.S.-based semiconductor company specializing in precision analog, mixed-signal, and high-reliability interface solutions for communications, industrial, and computing markets.

The DS2176Q belongs to Maxim's T-carrier interface product line, engineered specifically for T1/E1 receive-side synchronization, robbed-bit signaling supervision, and seamless integration with transceivers like the DS2180A.

FAQ

What is the primary function of the DS2176Q in a T1 system?

The DS2176Q performs two core functions: synchronizing loop-timed T1 PCM data (1.544 MHz) to system-side timing using a 2-frame buffer, and extracting, buffering, and supervising robbed-bit ABCD signaling. It ensures deterministic slip behavior on frame boundaries and delivers slip-compensated multiframe timing via SMSYNC-making it essential for telecom infrastructure where timing integrity and signaling reliability are critical. The DS2176Q replaces multiple discrete components in traditional T1 receive path designs.

How does the DS2176Q handle different framing standards like 193S and 193E?

The DS2176Q supports both 193S and 193E framing through the FMS pin: tied low for 193S (A/B signaling in frames 6/12), tied high for 193E (A/B/C/D in frames 6/12/18/24). SM0/SM1 configure integration depth and freeze duration per framing mode. In 193S mode, outputs C and D replicate prior multiframe A and B data, preserving signaling continuity. The DS2176Q maintains strict compliance with both standards without external configuration logic.

What is the significance of the SLIP output on the DS2176Q?

The SLIP output on the DS2176Q is an active-low, open-collector signal held low for exactly 65 SYSCLK cycles whenever a buffer slip occurs-either due to underflow or overflow. This precise duration enables reliable detection in downstream logic without ambiguity. SLIP indicates loss of frame alignment and triggers alarm reporting or system recovery routines. Unlike generic status flags, SLIP's fixed timing and frame-boundary occurrence make it a deterministic diagnostic tool in the DS2176Q's architecture.

Can the DS2176Q operate with both 1.544 MHz and 2.048 MHz system clocks?

Yes-the DS2176Q supports both 1.544 MHz and 2.048 MHz SYSCLK frequencies via the SCLKSEL pin: tied low for 1.544 MHz (F-bit passed through SSER), tied high for 2.048 MHz (F-bit dropped, MSB of channel 1 appears one bit after SFSYNC). Internal logic adjusts slip thresholds and timing relationships accordingly. This dual-rate capability allows the DS2176Q to serve North American T1 and international E1 infrastructure without redesign-confirming its role as a flexible, region-agnostic T1 receive buffer.

How does the DS2176Q manage signaling updates during alarm or slip conditions?

The DS2176Q freezes ABCD signaling updates during alarm or slip conditions using internal logic that asserts SIGFRZ high and holds prior multiframe values at outputs A/B/C/D. Freeze duration is programmable via SM0/SM1 (1–2 multiframes normally; limited to 2 during slip/alarm to minimize delay). Updates resume unconditionally at the next SMSYNC rising edge unless externally inhibited by SIGN or SIGH. This behavior ensures signaling integrity in the DS2176Q without requiring external supervision circuitry.