EL SEGUNDO, Calif. - September 2004 -- International Rectifier, IRŪ (NYSE: IRF), a world leader in power management technology, today introduced the IRU3146 pulse width modulated (PWM) dual synchronous buck controller and driver IC for point-of-load (POL) buck converters. Typical applications include dual phase ASIC and DDR memory power management circuits and datacom and telecommunications power supplies requiring multiple outputs.

The IRU3146 features 180 degrees out-of-phase operation which reduces input and output filter requirements resulting in fewer components. In addition, the IRU3146 is ideal for two-phase single- or dual-output synchronous buck converter applications. In single output two-phase applications, the solution can deliver up to 30A. In applications where two separate voltages are required, the solution will deliver up to 15A per output. The output voltage can be configured between 0.8V and 3.3V.

"The IRU3146 is a feature-rich dual PWM controller with integrated drivers that delivers high efficiency in typical synchronous buck converter applications. While using the IRU3146 in conjunction with two optimized MOSFET pairs (consisting of one IRF7821 in the high-side and one IRF8113 in the low-side of each pair), the converter reaches up to 90.8% efficiency at 12Vin, 3.3Vout at 30A full load condition," said Carl Smith, Marketing Manager for Networking and Communication DC-DC Products at International Rectifier.

Technical Highlights

The IRU3146 offers two independent programmable soft starts, which can provide individual output rise time control and limit the in-rush current during the start-up. Independent control over the output voltage rise times is especially important in systems requiring output voltage sequencing for sensitive load requirements. The IRU3146 can be configured for most types of output voltage sequencing.

Over-current protection can be set to either latch or hiccup mode shutdown. Hiccup current limit protection is important for systems requiring maximum up-time, and works by automatically restarting the converter once the output short condition is removed. The IRU3146 monitors the synchronous MOSFET on-resistance for over-current protection, enhancing converter efficiency and reducing cost by eliminating the current sense resistor.

In an over-temperature condition, the IC will shut down when the temperature exceeds 140°C. In synchronization mode, the IRU3146 is capable of accepting an external logic level signal from 200kHz to 400kHz which helps the overall system filter design at the input to the POL converters, since all POLs on-board can be synchronized together.

Part Number	Vin	Vref	Vout (adjustable)	Vout accuracy	Switching Frequency(kHz)	Deadtime	Vcc (Supply Voltage)	Package
IRU3146CF	4.5V to 12V (16V max)	0.8V	0.8V to 3.3V	+/- 1.5%	200-400kHz	100nS	4.5V to 16V	TSSOP-28 PIN

Availability and Pricing

The IRU3146 in the TSSOP-28 is US $1.51 each in 10,000-unit quantities and is available immediately.