Analog Devices Inc./Maxim Integrated DS2174QN

Overview

DS2174QN from Maxim Integrated is a software-programmable enhanced bit error-rate tester (EBERT) for telecom transmission validation, featuring 44-pin PLCC packaging, -40°C to +85°C industrial temperature range, pseudorandom pattern generation up to 2³²−1, 512-byte user-defined pattern memory, and dual independent serial/nibble/byte data interfaces operating at up to 155MHz transmit clock rate. It serves in CSU/DSU and smart jack diagnostics.

For engineers reviewing the DS2174QN datasheet, DS2174QN pinout, DS2174QN application, or DS2174QN equivalent, key selection considerations include its 48-bit BER counters, programmable polynomial feedback taps (up to 32), QRSS-compliant zero-suppression mode per T1.403, gapped-clock support via TCLK_EN/RCLK_EN, and parallel control port with 4-bit address bus and 8-bit data I/O.

Technical Context

The DS2174QN implements fully independent transmit and receive paths with synchronous sampling on RCLK/TCLK rising edges, supporting bit-, nibble- (4-bit), and byte- (8-bit) parallel modes. Its pattern synchronization logic detects loss-of-sync after 6 errors in 64 bits and supports auto-resync or manual resync via RSYNC bit.

It uses a programmable shift-register architecture for pseudorandom generation, where tap select registers define feedback positions and seed registers preload initial state; repetitive patterns are stored in 512-byte on-chip RAM accessed via indirect addressing, with pattern length configurable across 9 bits (PL0–PL8).

Key Specifications

Pinout & Package

DS2174QN is housed in a 44-pin Plastic Leaded Chip Carrier (PLCC) package with J-lead configuration, lead pitch 0.05 inches, body size 16.59mm × 16.59mm, and standard JEDEC MO-048A outline.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bit error-rate tester applications.

Compared with DS2174QN, DS2175Q extends diagnostic capability with jitter analysis and larger pattern memory but increases cost and footprint; MAX3675 offers minimal integration for pure pattern generation but cannot replace DS2174QN's full BERT functionality in telecom infrastructure test.

Availability

DS2174QN is available at Aetrix Electronics and suitable for channel service units, smart jack equipment, and TDM router validation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for DS2174QN 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) designs precision analog, mixed-signal, and high-speed communication ICs for industrial, telecom, and computing markets.

The DS2174QN belongs to Maxim's telecom test and diagnostics product line, engineered specifically for bit-error validation in T1/E1/OC-3 digital transmission facilities with emphasis on field-deployable reliability and software configurability.

FAQ

What is the maximum pseudorandom pattern length supported by the DS2174QN?

The DS2174QN supports pseudorandom pattern lengths up to 2³²−1, implemented via a programmable 32-bit shift register with configurable feedback tap positions. This capability enables full compliance with industry-standard test patterns including O.151 (2¹⁵−1), O.153 (2²⁰−1), and QRSS (2²⁰−1 with zero-suppression), all directly selectable through its tap/seed registers. The DS2174QN achieves this using internal polynomial generation logic that accepts any exponent n from 1 to 32.

Does the DS2174QN support both pattern generation and error analysis in the same device?

Yes, the DS2174QN integrates fully independent transmit and receive paths, allowing simultaneous pattern generation and bit error detection. Its receiver synchronizes to incoming patterns (polynomial or repetitive), counts bit errors using dedicated 48-bit error counters, and reports status via latched flags in the Status Register (Address 4h). This dual-path architecture eliminates external loopback wiring and enables true in-system BER measurement - a core capability distinguishing the DS2174QN from generator-only alternatives.

How does the DS2174QN handle clock gapping for TDM applications?

The DS2174QN supports clock gapping through dedicated TCLK_EN and RCLK_EN inputs, which gate the internal clock paths without disrupting data outputs. When TCLK_EN is deasserted, TDATn outputs hold their last value (static high/low), and TCLKO reflects the gapped timing. This behavior aligns with TDM slot timing requirements in CSUs and DSUs, enabling precise alignment to frame structures without external clock switches or added jitter - a feature explicitly documented in the DS2174QN's clock discussion section.

What is the function of the QRSS bit (CR1.3) in the DS2174QN's Control Register 1?

The QRSS bit (bit 3 of Control Register 1) enables T1.403-compliant zero-suppression in the DS2174QN's 2²⁰−1 pattern generation. When set, the device forces a logic-1 output whenever the next 14 bits in the sequence would otherwise be zeros - preventing extended zero runs that violate T1 line coding rules. This ensures accurate simulation of real-world QRSS traffic for testing smart jack and CSU receivers' ability to maintain synchronization under worst-case DC balance conditions.

Can the DS2174QN store and replay custom test patterns longer than 64 bytes?

Yes, the DS2174QN includes 512 bytes of on-chip RAM for storing user-defined repetitive patterns, accessible via indirect addressing using the parallel control port. Patterns up to 512 octets can be loaded, with length programmed via PL0–PL8 bits in Control Registers 3 and 4. The DS2174QN supports MSB-first or LSB-first transmission order and handles non-multiple-of-8 lengths by repeating pattern segments - for example, a 12-bit pattern is stored across three bytes and repeated in memory to ensure deterministic playback.