Analog Devices Inc./Maxim Integrated DS2175S+

Overview

DS2175S+ 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 at 5 V with industrial-grade 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 DS2175S+ datasheet, DS2175S+ pinout, DS2175S+ application, or DS2175S+ equivalent, key selection criteria include frame-synchronous slip control, dual-rate clock select (RCLKSEL/SCLKSEL), open-collector SLIP output timing (65 SYSCLK cycles), real-time buffer depth monitoring via RMSYNC/SMSYNC phase offset, and compatibility with DS2180A/DS2181A transceivers.

Technical Context

The DS2175S+ 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 correction logic ensures all slips occur strictly on frame boundaries, with FSD indicating direction (low = repeat, high = delete) and SLIP signaling occurrence as active-low pulse.

It features independent receive (RCLK/RCLKSEL) and system (SYSCLK/SCLKSEL) clock domain selection, serial/parallel backplane support (S/P input), and real-time buffer depth visibility via SMSYNC edge timing relative to RMSYNC - enabling proactive slip avoidance in telecom infrastructure.

Key Specifications

Pinout & Package

DS2175S+ is housed in a 16-pin SOIC (300 mil) package with 0.402–0.412 inch body width and 0.050 inch lead pitch.

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+ offers optimal balance of proven interoperability with legacy transceivers, precise frame-aligned slip control, and lower system-level design risk - especially where thermal environment is controlled and transceiver separation is preferred.

Availability

DS2175S+ is available at Aetrix Electronics and suitable for digital cross-connect systems, PABX-to-computer interfaces, and drop-and-insert equipment requiring stable component supply, long-term lifecycle support, and guaranteed 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

Maxim Integrated (acquired by Analog Devices in 2021) is a U.S.-based semiconductor company specializing in precision analog, mixed-signal, and high-reliability interface solutions for communications, industrial, and computing markets.

The DS2175S+ belongs to Maxim's telecom timing and synchronization product line, engineered specifically for T1/CEPT rate adaptation in carrier-grade digital transmission equipment where deterministic slip behavior and frame-aligned buffering are mandatory.

FAQ

What is the operating temperature range for DS2175S+?

The DS2175S+ is specified for commercial temperature operation from 0°C to +70°C. This range is validated per the device's Recommended DC Operating Conditions and AC Electrical Characteristics tables. For extended industrial environments (–40°C to +85°C), the DS2175N+ variant should be selected. Thermal derating is not required within the DS2175S+ specification limits, and no performance degradation occurs across this full range.

How does DS2175S+ handle clock domain mismatches between T1 and CEPT rates?

The DS2175S+ uses a 2-frame elastic store with comprehensive slip control logic to absorb short-term jitter and minor frequency offsets between 1.544 MHz and 2.048 MHz domains. Slips occur only on frame boundaries, and FSD/SLIP outputs report direction and occurrence. The buffer depth is continuously monitored via RMSYNC–SMSYNC timing, allowing real-time slip anticipation - all without external PLLs or FIFO controllers. This behavior is intrinsic to the DS2175S+ architecture and confirmed in its PCM BUFFER and SLIP CORRECTION CAPABILITY sections.

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

Yes, DS2175S+ supports both serial and parallel backplanes via the S/P input pin. When S/P = VDD, it operates in serial mode with SSER updated on each SYSCLK rising edge. When S/P = VSS, it enters parallel mode and uses look-ahead timing to present channel data 8 clocks early - enabling direct connection to shift registers like HC595 for parallel conversion. This dual-mode capability is documented in the PARALLEL COMPATIBILITY section and eliminates need for separate interface logic.

What is the function of the ALN pin on DS2175S+ and how is it used?

The ALN pin on DS2175S+ is a negative-edge-triggered align control that recenters the elastic store buffer at the next system-side frame boundary defined by SFSYNC. This feature is essential during power-up, reset, or system reinitialization to establish deterministic buffer depth without waiting for natural slip events. Forcing ALN low initiates recentering; if the current depth is already optimal, no slip occurs. This behavior is explicitly described in the BUFFER RECENTERING section of the DS2175S+ datasheet.

Is DS2175S+ pin-compatible with DS2180A or DS2181A transceivers?

No, DS2175S+ is not pin-compatible with DS2180A or DS2181A transceivers - it serves a complementary role as an elastic store buffer, not a line interface. However, DS2175S+ is explicitly designed for interoperability with those transceivers: its inputs (RCLK, RSER, RMSYNC) connect directly to DS2180A/DS2181A outputs, and its outputs (SSER, SMSYNC, SCHCLK) feed downstream TDM processing. This functional compatibility is stated in the FEATURES and DESCRIPTION sections, confirming co-design but not mechanical or electrical pin equivalence.