Analog Devices Inc./Maxim Integrated DS2175S

Overview

DS2175S from Dallas Semiconductor (now Maxim Integrated) is a low-power CMOS elastic-store memory IC designed for T1 (1.544 MHz) and CEPT (2.048 MHz) telecommunication interface synchronization. It serves as a rate buffer between asynchronous PCM data streams, provides 2-frame buffer depth, supports slip detection and recentering via ALN, and operates across industrial temperature range (–40°C to +85°C) in 16-pin SOIC package.

For engineers reviewing the DS2175S datasheet, DS2175S pinout, DS2175S application, or DS2175S equivalent, key selection considerations include frame-synchronous slip control, independent receive/system clock selection (RCLKSEL/SCLKSEL), real-time buffer depth monitoring via RMSYNC/SMSYNC timing, and compatibility with DS2180A/DS2181A transceivers in digital cross-connects and PABX-computer interfaces.

Technical Context

The DS2175S implements a dual-clock elastic store architecture that synchronizes incoming PCM data (sampled on RCLK falling edge at RSER) to the system backplane clock (SYSCLK rising edge updates SSER). Its 2-frame buffer depth varies by mode: 48 bytes for mixed-rate conversions (e.g., T1↔CEPT) and 64 bytes for same-rate operation (2.048 MHz ↔ 2.048 MHz).

Slip handling is deterministic and frame-boundary–locked: SLIP outputs an active-low open-collector pulse lasting 65 SYSCLK cycles; FSD reports direction (low = repeat, high = delete); ALN enables negative-edge–triggered buffer recentering; SMSYNC and RMSYNC edge spacing directly indicates real-time buffer depth for proactive slip avoidance.

Key Specifications

Pinout & Package

DS2175S is housed in a 16-pin SOIC package (300-mil width), with dimensions per datasheet revision: body width 0.290–0.300 in, thickness 0.089–0.095 in, lead pitch 0.050 in (BSC), and gull-wing lead profile optimized for reflow soldering.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar elastic store synchronization applications.

Compared with DS2175S, DS2175N extends operational range without changing functionality, while DS2185 offers measurable improvements in power and jitter performance with full pin and logic compatibility - making it the preferred upgrade path for future-proofing.

Availability

DS2175S is available at Aetrix Electronics and suitable for digital cross-connect systems, PABX-computer interfaces, and T1/CEPT line card designs requiring stable component supply, long-term obsolescence management, and traceable sourcing.

Supply support for DS2175S 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

Dallas Semiconductor, acquired by Maxim Integrated in 2001, specialized in precision analog, timing, and telecom interface ICs with emphasis on high-reliability industrial and communications applications.

The DS2175S belongs to the T1/CEPT elastic store product line, engineered specifically for frame-synchronous rate conversion in digital telephony infrastructure - targeting digital trunks, DACS, and PABX interface equipment.

FAQ

What is the primary function of the DS2175S in T1/CEPT systems?

The DS2175S functions as a frame-synchronous elastic store memory that bridges asynchronous T1 (1.544 MHz) and CEPT (2.048 MHz) data streams. It uses a 2-frame buffer to absorb short-term clock jitter, ensures slips occur only on frame boundaries, and provides hardware-controlled recentering via the ALN pin - all critical for maintaining data integrity in digital telephony infrastructure where DS2175S is deployed.

How does the DS2175S handle F-bit and E-bit framing in mixed-rate operation?

In T1-to-T1 mode, the DS2175S passes the F-bit through unchanged. In CEPT-to-T1 mode, it forces the F-bit to "1"; in T1-to-CEPT mode, it suppresses the F-bit and forces the E-bit to "1". This behavior is automatic and determined by RCLKSEL and SCLKSEL settings - no external logic is needed, simplifying system design around the DS2175S.

Can the DS2175S be used in both serial and parallel backplane architectures?

Yes - the DS2175S supports both via the S/P pin: tied low for parallel backplanes (with look-ahead timing for HC595 shift register interfacing), tied high for serial backplanes. The SCHCLK output provides channel boundary timing useful in serial-to-parallel conversion, making DS2175S adaptable to diverse telecom board layouts without redesign.

What is the significance of the RMSYNC and SMSYNC signals in DS2175S operation?

RMSYNC establishes receive-side frame/multiframe boundaries, while SMSYNC is a slip-compensated system-side multiframe output. The time difference between their rising edges directly reflects real-time buffer depth - enabling host firmware to monitor fill level and anticipate slips before they occur, a capability central to robust DS2175S system integration.

Is the DS2175S pin-compatible with other devices in the DS21xx family?

The DS2175S shares pinout and logic compatibility with DS2175N (industrial temp variant) and is backward-compatible with DS2185 (successor). However, it is not pin-compatible with DS2180A or DS2181A transceivers - those serve complementary roles (line interface) rather than elastic store buffering, and DS2175S interfaces directly with them but does not replace them.