Renesas HXT42100-DNU

Overview

HXT42100-DNU from Integrated Device Technology (IDT) is a single-channel Direct Modulated Laser (DML) driver IC for LR4 parallel optical modules, supporting 28Gbps data rates and 10km optical reach with IMOD = 50mAPP and IBIAS = 50mA at VCC = 2.5V. It integrates CML input equalization, laser bias/modulation control, temperature sensing, and 2-wire interface supervision in bare-die form for TOSA integration.

For engineers reviewing the HXT42100-DNU datasheet, HXT42100-DNU pinout, HXT42100-DNU application, or HXT42100-DNU equivalent, key selection considerations include its die-level packaging, programmable pulse width adjustment, input signal detect with squelch, laser disable control for both IMOD and IBIAS, and QSFP MSA compliance in compact optical transceiver designs.

Technical Context

The HXT42100-DNU implements a fully integrated DML driver architecture with pre-driver and main driver stages, DC-coupled output for direct TOSA connection, and on-die thermal monitoring via VTHERM. Its CML input supports equalization and polarity inversion to compensate for channel loss and layout skew.

Control is executed through a 2-wire (SCL/SDA) interface enabling real-time configuration of modulation current peaking amplitude/duration, input equalization level, and interrupt masking. Fault reporting includes laser disable status, burn-in mode, and power monitor outputs (IMON, MPD_OUT).

Key Specifications

Pinout & Package

Bare die package: nominal cut size 1350μm × 1120μm; designed for direct die attach in TOSA assemblies with symmetric pad layout to simplify wire bonding and minimize parasitic inductance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DML driver applications.

Compared with MAX3999ETJ+ and LMH6525IRGZT, the HXT42100-DNU uniquely delivers 28Gbps operation, integrated thermal supervision, and QSFP MSA-aligned 2-wire control in bare-die form-making it the only option qualified for production 100G-LR4 and 32GFC optical modules requiring die-in-TOSA integration.

Availability

HXT42100-DNU is available at Aetrix Electronics and suitable for 100GBASE-LR4 datacenter transceivers, 32G Fibre Channel storage links, and InfiniBand EDR optical modules requiring stable component supply and long-term die-level sourcing.

Supply support for HXT42100-DNU 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

Integrated Device Technology (IDT), now part of Renesas Electronics, is a fabless semiconductor company specializing in timing, memory interface, RF, and optical interconnect solutions for datacenter, communications, and enterprise systems.

The HXT42100-DNU belongs to IDT's high-speed optical driver product line, engineered specifically for die-level integration into LR4/CLR4 and EDR optical modules where minimal footprint, thermal efficiency, and MSA compliance are critical.

FAQ

What is the maximum supported data rate for the HXT42100-DNU?

The HXT42100-DNU supports data rates up to 28Gbps per channel, validated for use in IEEE-compliant 100GBASE-LR4 and InfiniBand EDR optical modules. This rate is achieved with CML input equalization enabled and proper termination matching. The HXT42100-DNU maintains signal integrity at this speed through optimized pre-driver and main driver stages, and its performance is specified across the full –5°C to +95°C operating temperature range.

Does the HXT42100-DNU include built-in temperature monitoring?

Yes, the HXT42100-DNU integrates an on-die temperature sensor with analog output on the VTHERM pin. This output provides a linear voltage proportional to junction temperature, enabling real-time thermal supervision and laser current derating in production modules. The HXT42100-DNU uses this sensor internally for fault detection and externally for host-controlled thermal management-no external thermistor or ADC is required for basic thermal safety.

Is the HXT42100-DNU supplied in a packaged IC format or as bare die?

The HXT42100-DNU is supplied exclusively as bare die in waffle pack (ordering code suffix -DNU). Its nominal cut size is 1350μm × 1120μm, and it features symmetric bond pads optimized for wire bonding directly into TOSA assemblies. The HXT42100-DNU does not have a plastic or ceramic package; it is intended for die-level integration with minimal external components to meet QSFP MSA mechanical and thermal constraints.

Can the HXT42100-DNU be used in 100GBASE-CLR4 modules?

Yes, the HXT42100-DNU supports up to 2km optical reach in 100GBASE-CLR4 modules, as confirmed in IDT's official product brief. Its 28Gbps capability, programmable pulse width adjustment, and laser disable functionality meet CLR4's lower power and shorter-reach requirements while reusing the same die design as LR4 variants. The HXT42100-DNU achieves this with identical IMOD/IBIAS settings but relaxed thermal and signal integrity margins compared to 10km operation.

What interface does the HXT42100-DNU use for configuration and monitoring?

The HXT42100-DNU uses a 2-wire interface compatible with standard I²C protocols (SCL and SDA pins) for full configuration and real-time monitoring. Through this interface, users can program input equalization, modulation current peaking, pulse width, interrupt masks, and laser enable/disable states. The HXT42100-DNU also provides analog monitor outputs (VTHERM, IMON, MPD_OUT) for additional system-level validation without requiring continuous digital polling.