Analog Devices Inc./Maxim Integrated DS2175S+T&R

Overview

DS2175S+T&R from Maxim Integrated (now part of Analog Devices) is a low-power CMOS elastic-store memory IC designed for T1/CEPT rate synchronization between asynchronous PCM data streams. It provides 2-frame buffering, frame-boundary-aligned slip control, and supports both 1.544 MHz (T1) and 2.048 MHz (CEPT) clock domains with independent receive/system clock selection. Used in digital cross-connects and PABX-to-computer interfaces.

For engineers reviewing the DS2175S+T&R datasheet, DS2175S+T&R pinout, DS2175S+T&R application, or DS2175S+T&R equivalent, key selection considerations include its dual-rate clock select inputs (RCLKSEL/SCLKSEL), open-collector SLIP output with 65-cycle pulse width, real-time buffer depth monitoring via RMSYNC–SMSYNC timing, and compatibility with DS2180A/DS2181A transceivers.

Technical Context

The DS2175S+T&R implements an elastic store using dual-frame (48–64 byte) synchronous RAM to absorb short-term frequency jitter between T1 and CEPT networks. Its slip logic ensures all frame slips occur strictly on frame boundaries, with FSD reporting direction (high = delete, low = repeat) and SLIP signaling occurrence as active-low open-collector pulse.

It operates in two primary modes: serial backplane (S/P = high) where SSER updates on SYSCLK rising edge, and parallel backplane (S/P = low) using look-ahead timing to deliver channel data 8 clocks early. Clock domain independence is enforced by separate RCLKSEL and SCLKSEL inputs tied to VSS or VDD.

Key Specifications

Pinout & Package

DS2175S+T&R is packaged in a 16-pin SOIC (300 mil) with gull-wing leads, footprint-compatible with industry-standard 16-pin DIP but offering improved thermal performance and board density.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS2175N and DS2185, the DS2175S+T&R offers the lowest-cost, minimal-footprint solution for commercial-temperature T1/CEPT rate adaptation-ideal for volume production where thermal margins are controlled and transceiver functions remain discrete.

Availability

DS2175S+T&R is available at Aetrix Electronics and suitable for digital cross-connect systems, PABX-to-computer interfaces, and T1/CEPT trunk line cards requiring stable component supply and long-term obsolescence management.

Supply support for DS2175S+T&R 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, now part of Analog Devices, is a semiconductor company specializing in precision analog, mixed-signal, and power management ICs for communications, computing, and industrial markets.

The DS2175S+T&R belongs to Maxim's telecom timing and interface product line, engineered specifically for T1/CEPT network synchronization in primary-rate digital transmission equipment such as DACS and digital trunks.

FAQ

What is the operating temperature range of the DS2175S+T&R?

The DS2175S+T&R is rated for commercial operation from 0°C to +70°C. This range is validated per the Absolute Maximum Ratings and Recommended Operating Conditions tables in the official datasheet. For applications requiring –40°C to +85°C operation, the DS2175N variant is specified and pin-compatible. The DS2175S+T&R should not be deployed outside its rated temperature envelope without thermal derating analysis.

How does the DS2175S+T&R handle F-bit and E-bit positioning in mixed-rate configurations?

In 1.544 MHz receive (RCLKSEL = 0) to 1.544 MHz system (SCLKSEL = 0) mode, the DS2175S+T&R passes the F-bit position from RSER to SSER. In 2.048 MHz to 1.544 MHz mode, it forces the F-bit to "1". In all 2.048 MHz system-side modes (SCLKSEL = 1), no F-bit exists and the E-bit is forced high. These behaviors are hardwired and require no configuration register writes - they are determined solely by RCLKSEL and SCLKSEL logic levels.

Can the DS2175S+T&R be used in parallel backplane applications, and what timing adjustments are needed?

Yes, the DS2175S+T&R supports parallel backplanes when S/P is tied to VSS. In this mode, it uses look-ahead timing to present channel data 8 SYSCLK cycles earlier than the SFSYNC rising edge - a feature documented in Figures 4 and 5 of the datasheet. To convert SSER to parallel format, an external HC595 shift register is required. No additional control signals or timing compensation logic is needed beyond correct S/P and clock domain setup.

What is the function of the ALN input, and how does it affect buffer operation?

The ALN input is a negative-edge-triggered align control that recenters the DS2175S+T&R's elastic store buffer at the next system-side frame boundary. When asserted, it forces the buffer depth to one frame - which may induce a slip if the current depth differs. This allows deterministic initialization during power-up or system reset without waiting for natural slip events. ALN does not clear slip status flags; SLIP and FSD retain their state until the next slip occurs.

Is the DS2175S+T&R pin-compatible with the DS2180A or DS2181A transceivers?

No, the DS2175S+T&R is not pin-compatible with the DS2180A or DS2181A transceivers - it is functionally complementary, not interchangeable. The DS2175S+T&R is an elastic store synchronizer, while DS2180A/DS2181A are T1/CEPT line interface transceivers. However, the datasheet explicitly states compatibility: DS2175S+T&R interfaces directly with DS2180A (T1) and DS2181A (CEPT) outputs, sharing common voltage levels, timing conventions, and framing protocols.