Analog Devices Inc./Maxim Integrated DS2175SN

Overview

DS2175SN from Maxim Integrated (formerly Dallas Semiconductor) is a low-power CMOS elastic-store memory IC designed for T1/CEPT rate buffering and frame-synchronous data stream alignment between asynchronous telecom networks. It supports 1.544 MHz (T1) and 2.048 MHz (CEPT) clock domains, provides 2-frame buffer depth, operates at 5 V supply, and features open-collector SLIP output with frame-boundary slip reporting. It is used in digital cross-connects and PABX-to-computer interfaces.

For engineers reviewing the DS2175SN datasheet, DS2175SN pinout, DS2175SN application, or DS2175SN equivalent, key selection considerations include its dual-rate clock select logic (RCLKSEL/SCLKSEL), slip-direction reporting via FSD, real-time buffer depth monitoring using RMSYNC–SMSYNC timing, and compatibility with DS2180A/DS2181A transceivers in telecom timing-critical systems.

Technical Context

The DS2175SN implements an elastic store architecture with two independent clock domains - receive (RCLK) and system (SYSCLK) - each selectable for 1.544 MHz or 2.048 MHz via RCLKSEL and SCLKSEL inputs. Its 2-frame buffer depth varies by mode: 48 bytes for mixed-rate conversions and 64 bytes for same-rate CEPT–CEPT operation.

Slip control is deterministic and frame-aligned: slips occur only on rising edges of RMSYNC or SFSYNC, with SLIP asserted low for exactly 65 SYSCLK cycles and FSD latching slip direction (low = repeat, high = delete). Buffer recentering is triggered by ALN's negative edge, enabling precise initialization without external logic.

Key Specifications

Pinout & Package

DS2175SN is available in 16-pin SOIC (300 mil) package per datasheet revision 06/13/97, with lead finish and thermal profile compliant for standard reflow soldering.

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 and MC145508P, the DS2175SN offers optimal balance of commercial-temperature operation, full T1/CEPT dual-rate configurability, and comprehensive slip diagnostics - making it the preferred choice for flexible, service-aware telecom interface design.

Availability

DS2175SN is available at Aetrix Electronics and suitable for digital cross-connects, PABX-to-computer interfaces, and drop-and-insert multiplexers requiring stable component supply and long-term obsolescence planning.

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 U.S.-based semiconductor company specializing in precision analog, mixed-signal, and high-reliability ICs for communications, industrial, and computing markets.

The DS2175SN belongs to Maxim's legacy telecom timing and interface product line, engineered specifically for T1/CEPT synchronization in digital transmission equipment where frame-aligned slip control and low-latency buffering are mandatory.

FAQ

What is the primary function of the DS2175SN in telecom systems?

The DS2175SN serves as an elastic-store memory IC that synchronizes asynchronous T1 (1.544 MHz) and CEPT (2.048 MHz) data streams at frame boundaries. It buffers incoming PCM data, detects and reports frame slips deterministically, and outputs slip-compensated data aligned to the system clock. Its role in DS2175SN-based designs is to eliminate timing mismatches between network segments without introducing bit errors or requiring external FIFO management logic.

How does the DS2175SN handle F-bit positioning in T1 applications?

In DS2175SN T1 applications (RCLKSEL = 0, SCLKSEL = 0), the F-bit position is passed through from RSER to SSER immediately after the rising edge of SFSYNC. When converting 2.048 MHz receive data to 1.544 MHz system clock (RCLKSEL = 1, SCLKSEL = 0), the DS2175SN forces the F-bit position to logic "1". No F-bit is generated in pure 2.048 MHz system-side operation, as CEPT frames lack this field.

Can the DS2175SN operate in both serial and parallel backplane configurations?

Yes, the DS2175SN supports both configurations via the S/P input: tie S/P to VDD for serial mode (channel-1 aligned to SFSYNC), or to VSS for parallel mode (look-ahead timing with 8-clock advance). In parallel mode, DS2175SN's SCHCLK output and SSER stream enable straightforward serial-to-parallel conversion using an HC595 shift register, eliminating custom timing logic.

What is the significance of the SMSYNC output in DS2175SN system design?

The SMSYNC output in DS2175SN is a slip-compensated multiframe sync pulse whose timing relative to RMSYNC directly indicates real-time buffer depth. By measuring the rising-edge offset between RMSYNC and SMSYNC, designers can monitor fill level continuously - enabling proactive slip mitigation, dynamic bandwidth allocation, and diagnostic logging without CPU polling or additional sensors.

Is the DS2175SN pin-compatible with the DS2180A or DS2181A transceivers?

No, the DS2175SN is not pin-compatible with DS2180A or DS2181A transceivers; it is functionally complementary. The DS2175SN interfaces *with* those devices - receiving serial data from DS2180A (T1) or DS2181A (CEPT) transceivers at RSER and outputting synchronized data at SSER. Their interconnection follows documented timing relationships in the DS2175SN datasheet, not shared pin mapping.