Renesas ISL6744AUZ

Overview

ISL6744AUZ from Renesas Electronics (formerly Intersil) is a voltage-mode PWM controller IC for primary-side half-bridge and full-bridge DC/DC converters, delivering precise 35ns propagation delay, adjustable 100kHz–2MHz oscillator frequency, 1A gate drivers, and 35ns minimum deadtime control. It targets unregulated bus converter applications in telecom/datacom power systems.

For engineers reviewing the ISL6744AUZ datasheet, ISL6744AUZ pinout, ISL6744AUZ application, or ISL6744AUZ equivalent, key selection considerations include its 8-pin MSOP package, -40°C to +105°C operating range, 9–16V VDD supply, 0.6V current-sense threshold, and integrated thermal shutdown at 145°C.

Technical Context

The ISL6744AUZ implements a dual-output voltage-mode PWM architecture with independent CT/RTD-based oscillator timing, where switching frequency is set by external resistor RTD and capacitor CT. Its internal oscillator supports up to 2MHz operation with programmable charge/discharge currents (156µA typical charge, 55× I_RTD discharge gain).

Deadtime is precisely controlled via CT discharge duration, enabling ZVS transitions as low as 35ns. Overcurrent protection uses a retriggerable 50µs one-shot timer and soft-start capacitor discharge (15µA sink) to initiate delayed shutdown when CS exceeds 0.6V, with recovery triggered at 0.27V SS voltage.

Key Specifications

Pinout & Package

ISL6744AUZ is housed in an 8-lead MSOP package (Pb-free, RoHS compliant), with exposed pad for thermal enhancement. Pin layout follows standard SOIC/MSOP top-view orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PWM controller applications.

Compared with UCC2897A and LM5045, the ISL6744AUZ offers superior integration for cost-sensitive unregulated bridge converters, trading off regulation precision and advanced features for minimal external component count, 1A on-chip drivers, and sub-40ns propagation delay.

Availability

ISL6744AUZ is available at Aetrix Electronics and suitable for telecom bus converters, datacom DC transformers, and industrial isolated power supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for ISL6744AUZ 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

Renesas Electronics acquired Intersil in 2017 and maintains its high-performance analog and power management portfolio. The company specializes in energy-efficient semiconductor solutions for industrial, automotive, and communications infrastructure.

The ISL6744AUZ belongs to Intersil's legacy intermediate bus controller product line, designed specifically for cost-optimized, unregulated DC/DC conversion in telecom and datacom equipment using half-bridge and full-bridge topologies.

FAQ

What is the maximum operating frequency of the ISL6744AUZ?

The ISL6744AUZ supports an adjustable oscillator frequency up to 2MHz, set by external RTD resistor and CT capacitor values. At typical conditions (RTD = 51.1kΩ, CT = 470pF), it operates near 235kHz in the reference application. The 2MHz upper limit enables high-frequency designs that reduce transformer and filter size in space-constrained systems. ISL6744AUZ achieves this with 156µA internal charge current and scalable discharge gain.

Does the ISL6744AUZ support both half-bridge and full-bridge topologies?

Yes, the ISL6744AUZ is explicitly designed for both half-bridge and full-bridge unregulated DC/DC converters. Its dual complementary outputs (OUTA and OUTB) provide 180° phase-shifted drive signals with adjustable deadtime down to 35ns-critical for preventing shoot-through in either topology. The FN9147 datasheet confirms use in "full and half-bridge topologies" and provides a full-bridge-capable functional block diagram.

What is the purpose of the RTD pin on the ISL6744AUZ?

The RTD pin on the ISL6744AUZ sets the oscillator's discharge current, which directly determines deadtime and influences frequency accuracy. A resistor from RTD to GND establishes a reference current; the internal circuit generates a discharge current nominally 55× that value. This architecture allows precise, temperature-stable deadtime control independent of CT value-enabling robust ZVS tuning. ISL6744AUZ relies on RTD for both timing fidelity and fault-margin optimization.

How does overcurrent protection work in the ISL6744AUZ?

The ISL6744AUZ implements delayed overcurrent shutdown using the CS pin (0.6V threshold) and soft-start capacitor (SS). When overcurrent is detected, the SS charging current stops and a 15µA discharge begins. If SS voltage falls below 3.9V, outputs disable; recovery starts only after SS drops to 0.27V. A 50µs retriggerable one-shot prevents false trips from transients. This behavior is fully documented in the ISL6744AUZ datasheet Section "Overcurrent Operation".

Is the ISL6744AUZ pin-compatible with other variants in the ISL6744 family?

Yes, the ISL6744AUZ shares identical pinout and electrical specifications with the ISL6744AU (non-Pb-free) and ISL6744AB/ABZ (SOIC-8), all using the same M8.118 (MSOP) or M8.15 (SOIC) package drawings. Functionally, all variants operate identically across -40°C to +105°C. The "Z" suffix denotes Pb-free annealed terminations per RoHS, with no impact on pin assignment, timing, or drive capability-making ISL6744AUZ a drop-in replacement for ISL6744AU in new designs.