Analog Devices Inc./Maxim Integrated DS2175SN+

Overview

DS2175SN+ from Maxim Integrated (now part of Analog Devices) is a low-power CMOS elastic-store memory IC designed for T1/CEPT rate buffering and synchronization between asynchronous PCM data streams. It supports 1.544 MHz (T1) and 2.048 MHz (CEPT) clock domains, provides 2-frame buffer depth, slip detection and reporting, and operates across industrial temperature range (–40°C to +85°C). It is used in digital cross-connects, PABX-to-computer interfaces, and drop-and-insert equipment.

For engineers reviewing the DS2175SN+ datasheet, DS2175SN+ pinout, DS2175SN+ application, or DS2175SN+ equivalent, key selection considerations include frame-synchronized slip control, dual-rate clock select (RCLKSEL/SCLKSEL), open-collector SLIP output with FSD direction reporting, real-time buffer depth monitoring via RMSYNC/SMSYNC timing, and compatibility with DS2180A/DS2181A transceivers.

Technical Context

The DS2175SN+ implements an elastic store using dual-rate, frame-aligned 2-frame buffering (48 or 64 bytes depending on mode) to synchronize T1 and CEPT data streams without requiring external support logic. Its slip control logic ensures all slips occur strictly on frame boundaries, with ALN-triggered recentering and latched FSD output indicating slip direction (buffer full vs. empty).

It features independent receive (RCLK/RCLKSEL) and system (SYSCLK/SCLKSEL) clock domain selection, serial/parallel backplane support via S/P input, and outputs including SCHCLK (channel clock), SMSYNC (slip-compensated multiframe sync), and SSER (system serial data updated on SYSCLK rising edge).

Key Specifications

Pinout & Package

DS2175SN+ is housed in a 16-pin SOIC (300 mil) package, pin-compatible with the 16-pin DIP variant (DS2175N). The device uses single 5 V supply and requires no external biasing components.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar elastic store and T1/CEPT rate buffering applications.

Compared with DS2175N+, DS2175SN+ provides identical functionality in a smaller SOIC footprint suitable for high-density line cards; compared with DS2185+, it retains full clock domain independence and simpler layout, making it preferable for designs requiring precise control over RCLK/SYSCLK sourcing and slip behavior.

Availability

DS2175SN+ is available at Aetrix Electronics and suitable for digital cross-connect systems, PABX-to-computer interfaces, and drop-and-insert multiplexers requiring stable component supply, long-term lifecycle support, and industrial-temperature qualification.

Supply support for DS2175SN+ 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 semiconductor company specializing in precision analog, mixed-signal, and high-reliability ICs for communications, industrial, and computing applications.

The DS2175SN+ belongs to Maxim's telecom timing and interface product line, engineered specifically for T1/CEPT synchronization in carrier-grade digital transmission equipment where deterministic slip behavior and frame-aligned buffering are critical.

FAQ

What is the primary function of the DS2175SN+ in T1/CEPT systems?

The DS2175SN+ serves as an elastic-store memory IC that synchronizes asynchronous T1 (1.544 MHz) and CEPT (2.048 MHz) PCM data streams on frame boundaries. It uses a 2-frame buffer with comprehensive slip control logic to absorb short-term jitter, report slip events via SLIP and FSD outputs, and maintain data integrity across rate domains - all without external support logic. Its role is fundamental to reliable digital trunk interfacing and cross-connect operation.

Does the DS2175SN+ support both T1 and CEPT clock rates simultaneously?

Yes, the DS2175SN+ supports independent configuration of receive and system clock domains: RCLKSEL selects 1.544 MHz or 2.048 MHz for RCLK, and SCLKSEL selects the same for SYSCLK. This enables four combinations - T1→T1, CEPT→CEPT, T1→CEPT, and CEPT→T1 - with appropriate F-bit or E-bit handling per mode. The DS2175SN+ does not generate clocks but synchronizes data between them using its elastic store architecture.

How does the DS2175SN+ indicate and handle frame slips?

The DS2175SN+ signals frame slips via two dedicated outputs: SLIP (active-low open-collector pulse held low for 65 SYSCLK cycles) and FSD (latched logic level indicating direction - low = buffer emptied/data repeated, high = buffer filled/data deleted). Slips occur only on frame boundaries, and the buffer is automatically recentered to one-frame depth. ALN input allows manual recentering at any time, triggering a slip only if depth adjustment is needed.

Can the DS2175SN+ be used in parallel backplane applications?

Yes, the DS2175SN+ supports parallel backplanes via the S/P input: when tied to VSS, it enters parallel mode and generates a look-ahead timing signal (SCHCLK) that presents channel data 8 clocks early. This allows direct interfacing with shift registers like the HC595 to convert SSER serial output into parallel format. No additional timing logic is required, simplifying system-level design for channelized TDM architectures.

What is the significance of RMSYNC and SMSYNC timing in DS2175SN+ operation?

RMSYNC (receive multiframe sync) and SMSYNC (system multiframe sync) define frame/multiframe boundaries on their respective sides. The time interval between their rising edges directly reflects real-time buffer depth - enabling continuous monitoring without polling. Impending slips can be predicted by observing RMSYNC–SMSYNC drift, and SMSYNC's 65-SYSCLK pulse width provides a stable reference for depth calculation. This capability is unique to the DS2175SN+ and critical for proactive network timing management.