Analog Devices Inc./Maxim Integrated DS2175

Overview

DS2175 from Maxim Integrated (formerly Dallas Semiconductor) 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 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 DS2175 datasheet, DS2175 pinout, DS2175 application, or DS2175 equivalent, key selection considerations include its dual-rate clock select logic (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 in telecom infrastructure designs.

Technical Context

The DS2175 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 operates exclusively on frame boundaries, with ALN-triggered recentering and FSD-reported slip direction (buffer empty/deleted vs. full/repeated).

It supports parallel and serial backplane interfacing via S/P input, generates SCHCLK for channel boundary timing, and uses RMSYNC/SFSYNC to establish multiframe alignment without requiring continuous sync pulses-internal counters maintain frame position once initialized.

Key Specifications

Pinout & Package

DS2175 is available in 16-pin DIP (300 mil) and 16-pin SOIC (300 mil) packages. Both share identical pinout and electrical characteristics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS2175, DS2185 integrates line interface functionality but increases design complexity and power, while MC145508 offers lower cost and simplicity at the expense of CEPT compatibility and advanced slip diagnostics - DS2175 remains optimal for dual-standard, diagnostic-aware telecom synchronization.

Availability

DS2175 is available at Aetrix Electronics and suitable for digital cross-connect systems, PABX-to-computer interfaces, and T1/E1 drop-and-insert multiplexers requiring stable component supply across extended product lifecycles.

Supply support for DS2175 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 Dallas Semiconductor in 2001) designs precision analog, mixed-signal, and high-reliability semiconductor solutions for communications, industrial, and computing markets.

The DS2175 belongs to Maxim's legacy telecom timing and synchronization IC family, engineered specifically for T1/CEPT rate adaptation, elastic storage, and jitter-tolerant PCM interfacing in carrier-class infrastructure equipment.

FAQ

What is the primary function of the DS2175 in telecom systems?

The DS2175 serves as a dual-rate elastic store memory that synchronizes asynchronous T1 (1.544 MHz) and CEPT (2.048 MHz) PCM data streams. It buffers two frames of data, performs slip correction only on frame boundaries, and maintains alignment between disparate clock domains - enabling interoperability in digital cross-connects, PABX interfaces, and trunk equipment without external FIFOs or complex timing logic.

Does the DS2175 support both T1 and CEPT standards simultaneously?

Yes, the DS2175 supports both standards through independent clock domain configuration: RCLKSEL selects the receive clock rate (1.544 or 2.048 MHz), and SCLKSEL selects the system clock rate. This allows flexible combinations including T1-to-CEPT, CEPT-to-T1, T1-to-T1, and CEPT-to-CEPT operation - all within a single DS2175 device without hardware changes.

How does the DS2175 report slip events and their direction?

The DS2175 reports slip events via two dedicated outputs: SLIP (active-low open-collector pulse held for 65 SYSCLK cycles) and FSD (frame slip direction). FSD is latched at each slip: low indicates buffer underflow (a frame was repeated), high indicates overflow (a frame was deleted). These signals enable real-time fault logging and system-level recovery actions in the DS2175-based design.

What is the role of the ALN pin on the DS2175?

The ALN (Align) pin on the DS2175 is a negative-edge-triggered input that forces immediate buffer recentering at the next system-side frame boundary. This feature is essential during power-up initialization or system reset to establish known buffer depth. If the current depth differs from one frame, a slip occurs during recentering - the DS2175 reports this via SLIP and FSD as with normal slips.

Can the DS2175 operate in parallel backplane mode, and how is it configured?

Yes, the DS2175 supports parallel backplane interfacing via the S/P pin: tying S/P to VSS enables parallel mode, which uses internal look-ahead logic to present data 8 clocks early on SSER. This timing allows direct connection to an HC595 shift register for serial-to-parallel conversion. In this mode, SCHCLK provides channel boundary timing, and the DS2175 eliminates need for external parallel interface logic.