Efficient convertor boosts power density

Edited by the Electronicstalk editorial team Sep 25, 2007

Synchronous buck power convertor uses a novel low-voltage technique that enables high-frequency switching with high gate drive.

The SC4612 28V synchronous buck power convertor from Solid State Supplies enables system designers to increase port density in datacomms applications while reducing board size.

With a wide input range and a programmable 1.2MHz frequency for compact power supply designs, the SC4612's synchronous rectified buck topology results in 95% peak efficiency that provides compact onboard DC/DC convertor designs with 93W/in2 power density.

The SC4612 is a voltage-mode synchronous, PWM controller that operates in a 4.5 to 28V input voltage range and drives external N-channel MOSFETs.

The design uses a novel low-voltage technique that enables high-frequency switching with high gate drive.

The output voltage can be as low as 0.5V.

Running at a constant 1.2MHz frequency that can be programmed using an external capacitor, the device's 1.7A gate drive current is capable of driving large MOSFETs, resulting in efficient 40A single phase convertor designs.

The device supports an asynchronous startup mode to keep the lower side MOSFET turned off until output is within regulation so that the external bus is not discharged.

This is an ideal feature for applications with preset external voltage or prebiased output voltage.

Built-in crossconduction-prevention circuitry prevents shoot-through, minimising dead time and losses.

The SC4612 features programmable current limit with built-in hiccup mode and over temperature protection.

It is available in either an MLPD-12 or a SOIC-14 package in lead-free versions that meet RoHS/WEEE specifications and has a -40 to +125C junction operating temperature range.