Analog Devices Inc./Maxim Integrated MAX9425EHJ+

Overview

MAX9425EHJ+ from Maxim Integrated is a high-speed quad PECL-to-ECL differential translator IC designed for clock and data distribution in backplane and base station systems. It features 0.24ps(RMS) added random jitter, <90ps channel-to-channel skew in asynchronous mode, 420ps propagation delay, integrated 50Ω series output termination, and operates across -40°C to +85°C with ±2.375V to ±5.5V dual supplies.

For engineers reviewing the MAX9425EHJ+ datasheet, MAX9425EHJ+ pinout, MAX9425EHJ+ application, or MAX9425EHJ+ equivalent, this page delivers verified electrical parameters, synchronous/asynchronous timing behavior, output termination architecture, thermal performance in TQFP packaging, and real-world substitution guidance for telecom and ATE signal integrity designs.

Technical Context

The MAX9425EHJ+ implements four independent bipolar PECL-to-ECL translation channels with selectable synchronous (clocked) or asynchronous (transparent) operation via the differential SEL input. Its internal 50Ω series output termination and 8mA pulldown current source eliminate external termination components for ECL loads referenced to VGG.

It accepts PECL inputs referenced to VCC and delivers ECL outputs referenced to VGG, requiring three distinct supply rails: VCC (+2.375V to +5.5V), VEE (-2.375V to -5.5V), and VGG (ground reference). Input common-mode range spans VGG to VCC − 0.2V, while output common-mode voltage is fixed at VGG − 1.25V (typ).

Key Specifications

Pinout & Package

MAX9425EHJ+ is housed in a 32-pin 5mm × 5mm TQFP package with exposed paddle (thermal pad connected to VGG). Pin 1 is top-left corner; corner pins (1, 8, 25, 32) are VCC or IN0/IN0; all VGG pins (11, 17, 24, 30) and VEE pins (14, 20, 21, 27) are internally tied to respective supply planes.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PECL-to-ECL translation applications.

Compared with MAX9425EHJ+, MAX9427EHJ+ adds input termination at the cost of slightly reduced bandwidth, while SK4430 offers mechanical compatibility but sacrifices jitter performance and thermal reliability-making MAX9425EHJ+ optimal for new high-speed telecom clocking where jitter and thermal management are critical.

Availability

MAX9425EHJ+ is available at Aetrix Electronics and suitable for central office clock distribution, DSLAM backplane signaling, and base station RF timing applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MAX9425EHJ+ 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 U.S.-based semiconductor company specializing in precision analog, mixed-signal, and high-speed interface solutions for industrial, communications, and computing markets.

The MAX9424–MAX9427 family was engineered specifically for ultra-low-jitter, low-skew PECL-to-ECL translation in telecom infrastructure clock trees and high-speed test equipment-prioritizing jitter floor, channel matching, and robust dual-supply operation.

FAQ

What supply voltages does the MAX9425EHJ+ require?

The MAX9425EHJ+ requires three independent supply connections: VCC (+2.375V to +5.5V), VEE (-2.375V to -5.5V), and VGG (ground reference). VCC powers the PECL input stage, VEE sets the ECL output swing lower limit, and VGG serves as the common-mode reference for outputs and termination. The MAX9425EHJ+ does not require symmetrical supplies, enabling flexible rail selection in mixed-voltage systems.

How does the MAX9425EHJ+ handle synchronous versus asynchronous operation?

The MAX9425EHJ+ selects between modes using the differential SEL input: SEL = high enables asynchronous (transparent) operation where inputs pass directly to outputs with 420ps delay; SEL = low enables synchronous operation where all four channels are clocked by the differential CLK input on its rising edge. In synchronous mode, the MAX9425EHJ+ achieves 10ps channel-to-channel skew and supports up to 3.0GHz clock frequencies.

Does the MAX9425EHJ+ need external output termination resistors?

No, the MAX9425EHJ+ does not require external output termination resistors. It integrates 50Ω series output termination on each OUT_/OUT_ pair, along with an 8mA internal pulldown current source, allowing direct connection to 50Ω transmission lines terminated to VGG − 2.0V. This eliminates four external resistors per channel and reduces PCB layout complexity compared to open-emitter variants like MAX9424EHJ+.

What is the guaranteed differential output voltage of the MAX9425EHJ+ at 3GHz?

The MAX9425EHJ+ guarantees a minimum differential output voltage (VOH − VOL) of 600mV at 3GHz clock frequency under specified conditions (VCC − VGG = 3.3V, VGG − VEE = 3.3V, TA = −40°C to +85°C). This meets ECL-100K logic level requirements and ensures sufficient noise margin for downstream ECL receivers operating at full speed.

Can the MAX9425EHJ+ be used in place of the SK4430?

Yes, the MAX9425EHJ+ is functionally compatible with SK4430 and shares identical pinout, supply requirements, and 50Ω output architecture. However, the MAX9425EHJ+ improves upon SK4430 with lower added random jitter (0.24ps vs. 0.35ps RMS), extended temperature qualification (−40°C to +85°C), and enhanced thermal performance due to its exposed paddle TQFP package-making it a superior drop-in upgrade for new and legacy designs.