Analog Devices Inc./Maxim Integrated MAX9426EHJ

Overview

MAX9426EHJ from Maxim Integrated is a high-speed quad PECL-to-ECL differential translator with integrated 100Ω differential input termination and open-emitter outputs, delivering 0.24ps(RMS) added random jitter, <90ps channel-to-channel skew in asynchronous mode, and guaranteed 500mV differential output at 3GHz clock frequency for precision clock distribution in telecom backplanes.

For engineers reviewing the MAX9426EHJ datasheet, MAX9426EHJ pinout, MAX9426EHJ application, or MAX9426EHJ equivalent, this device is selected for low-jitter signal translation where input impedance matching, thermal stability across -40°C to +85°C, and synchronous/asynchronous mode flexibility are critical design requirements.

Technical Context

The MAX9426EHJ implements four independent bipolar differential translator channels with dual-mode operation: asynchronous (data-driven, SEL = high) with 420ps typical propagation delay, or synchronous (clocked, SEL = low) with 580ps typical CLK-to-OUT delay and 10ps guaranteed channel-to-channel skew. Its 100Ω integrated differential input termination eliminates external bias networks for PECL sources.

It operates from asymmetric dual supplies (+2.375V to +5.5V on VCC, -2.375V to -5.5V on VEE) referenced to VGG, supporting ECL-level output common-mode voltage (VGG − 1.25V typical) and requiring external 50Ω-to-VGG−2V termination for open-emitter outputs. Jitter performance is characterized at 2.0Gbps PRBS and 3.0GHz clock inputs.

Key Specifications

Pinout & Package

MAX9426EHJ is housed in a 32-pin 5mm × 5mm TQFP package with exposed pad (thermal pad connected to VGG). Pin 1 is VCC; corner pins (1, 8, 24, 32) connect to VGG per datasheet note. All supply pins require local 0.01µF + 0.1µF ceramic bypassing to VGG.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX9426EHJ, MAX9424EHJ demands external input termination and increases layout risk, while MAX9427EHJ trades output flexibility for reduced component count - MAX9426EHJ uniquely balances integrated input matching with externally configurable output swing.

Availability

MAX9426EHJ is available at Aetrix Electronics and suitable for central office backplane clock distribution, DSLAM backplane timing, and base station clock tree applications requiring stable component supply, long-term lifecycle support, and guaranteed extended temperature performance.

Supply support for MAX9426EHJ 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 and mixed-signal ICs for demanding industrial, communications, and computing applications, with expertise in high-speed timing, power management, and interface solutions.

The MAX9424–MAX9427 family was engineered specifically for ultra-low-jitter PECL-to-ECL translation in telecom infrastructure, addressing skew, jitter, and termination challenges in multi-gigabit clock and data distribution systems.

FAQ

What is the function of the SEL pins on the MAX9426EHJ?

The SEL and SEL pins on the MAX9426EHJ form a differential select input that determines operational mode: when SEL = high and SEL = low, the device operates asynchronously (each channel responds directly to its IN_ input); when SEL = low and SEL = high, it operates synchronously, clocking all four channels simultaneously on the rising edge of CLK/CLK. This dual-mode capability makes MAX9426EHJ adaptable to both data-driven and clock-synchronized system architectures without redesign.

Does the MAX9426EHJ require external input termination resistors?

No, the MAX9426EHJ does not require external input termination resistors because it integrates matched 100Ω differential termination between each IN_ and IN_ pair, as confirmed in the Ordering Information table and Detailed Description section. This feature eliminates the need for discrete 100Ω resistors typically required for PECL input biasing, reducing component count and improving impedance matching consistency across all four channels of MAX9426EHJ.

What output termination is required for the MAX9426EHJ?

The MAX9426EHJ requires external 50Ω termination from each OUT_ and OUT_ pin to VGG − 2V (a Thevenin-equivalent termination is also acceptable), as specified in the Applications Information section. Unlike MAX9425EHJ or MAX9427EHJ, MAX9426EHJ has open-emitter outputs with no internal series resistance, so proper termination is essential to achieve the guaranteed 500mV differential output swing at 3GHz and maintain low output-to-output skew.

What is the maximum clock frequency supported by the MAX9426EHJ in synchronous mode?

The MAX9426EHJ supports a maximum clock frequency of 3.0GHz in synchronous mode (SEL = low), provided the differential output voltage swing (VOH − VOL) remains ≥500mV, as stated in the AC Electrical Characteristics table. This specification is validated across the full −40°C to +85°C operating temperature range and enables use in OC-48, STM-16, and other 2.5G–3G telecom clock distribution applications requiring precise edge alignment.

How does the MAX9426EHJ handle power supply decoupling?

The MAX9426EHJ requires dedicated high-frequency decoupling: each VCC pin must be bypassed to VGG with parallel 0.01µF and 0.1µF ceramic capacitors placed as close as possible to the pin, and identical networks must be used between each VEE pin and VGG. The datasheet emphasizes using multiple vias to VGG and avoiding sharp trace corners to minimize inductance - these practices are critical to maintaining stable 3GHz operation and preventing supply-induced jitter in MAX9426EHJ.