Analog Devices Inc./Maxim Integrated MAX9424EHJ

Overview

MAX9424EHJ from Maxim Integrated is a high-speed quad PECL-to-ECL differential translator IC designed for clock and data distribution in backplane and telecom timing systems. It delivers 0.24ps(RMS) added random jitter, <90ps channel-to-channel skew in asynchronous mode, and guaranteed 500mV differential output at 3GHz - enabling precise signal integrity in DSLAM and base station clock trees.

For engineers reviewing the MAX9424EHJ datasheet, MAX9424EHJ pinout, MAX9424EHJ application, or MAX9424EHJ equivalent, this device supports synchronous/asynchronous operation via SEL input, features open-input/open-emitter termination, operates across –40°C to +85°C, and requires dual-supply biasing (VCC/VGG/VEE) for PECL input and ECL output level translation.

Technical Context

The MAX9424EHJ implements four independent bipolar differential translator channels with no internal clock buffering - propagation delay is determined solely by input-to-output path (420ps typ. in asynchronous mode). Its open-input architecture requires external termination, while open-emitter outputs demand 50Ω-to-VGG–2V termination for optimal skew and amplitude.

Operation mode is selected via differential SEL pins: high enables asynchronous per-channel translation; low enables synchronous edge-triggered output on CLK. The device uses VGG as common-mode reference for both inputs (PECL-referenced to VCC) and outputs (ECL-referenced to VGG), requiring strict decoupling of all three supply rails.

Key Specifications

Pinout & Package

MAX9424EHJ is housed in a 32-pin 5mm × 5mm TQFP package with exposed thermal pad (pin 17 connected to VGG). Corner pins (1, 8, 24, 32) are tied to VGG for enhanced grounding and thermal conduction.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX9424EHJ, MAX9425EHJ reduces BOM count via on-die 50Ω outputs but increases sensitivity to VGG rail noise, while SK4426 offers identical performance with alternate branding - making MAX9424EHJ optimal when external termination provides better control over rise/fall symmetry and skew tuning.

Availability

MAX9424EHJ is available at Aetrix Electronics and suitable for central office backplane clock distribution, DSLAM backplane timing, and base station RF clocking requiring stable component supply across extended temperature and high-reliability production cycles.

Supply support for MAX9424EHJ 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 industrial, communications, and computing applications, with emphasis on signal integrity and power efficiency.

The MAX9424–MAX9427 family targets high-speed timing infrastructure in telecom and test equipment, delivering lowest-jitter PECL-to-ECL translation with configurable synchronization and flexible termination options.

FAQ

What is the recommended termination for MAX9424EHJ outputs?

MAX9424EHJ features open-emitter outputs and requires external 50Ω termination to VGG–2V for proper ECL common-mode voltage (VOCM ≈ VGG–1.25V) and differential swing ≥500mV. Using Thevenin-equivalent termination (e.g., 100Ω to VGG and 100Ω to VEE) is acceptable if VOCM remains within –1.50V to –1.05V relative to VGG. Incorrect termination causes amplitude loss and increased skew.

Does MAX9424EHJ support both synchronous and asynchronous operation?

Yes, MAX9424EHJ supports both modes via the differential SEL/SEL pins. When SEL = high, all four channels operate asynchronously (transparent translation). When SEL = low, all channels synchronize to the differential CLK/CLK input on the rising edge. The mode selection is hardware-controlled with no setup time or configuration overhead - MAX9424EHJ transitions instantly between modes.

What supply voltages does MAX9424EHJ require?

MAX9424EHJ requires three independent supplies: VCC (+2.375V to +5.5V), VGG (typically 0V, serving as reference), and VEE (–2.375V to –5.5V). VCC powers the PECL input stage; VEE powers the ECL output stage; VGG is the common reference for both. Each VCC and VEE pin must be bypassed to VGG with 0.01µF + 0.1µF ceramic capacitors placed adjacent to the package.

How is channel-to-channel skew specified for MAX9424EHJ?

MAX9424EHJ specifies channel-to-channel skew as <90ps maximum in asynchronous mode and 10ps typical in synchronous mode. This is measured between output crossing points of same-edge transitions across all four channels under matched loading and temperature. The 90ps max asynchronous skew enables deterministic timing in multi-lane clock distribution without global synchronization - a key requirement for MAX9424EHJ in backplane applications.

Can unused inputs on MAX9424EHJ be left floating?

No, unused inputs on MAX9424EHJ must be biased to prevent noise-induced toggling. Per Maxim's Figure 5, each unused differential input pair (e.g., IN0/IN0) should be terminated with a 100Ω resistor across the pair and biased via 1kΩ resistors to VCC and VGG. Floating inputs cause erratic output behavior, increased jitter, and potential EMI - this requirement is critical to achieving the 0.24ps(RMS) jitter spec claimed for MAX9424EHJ.