Synchronous convertor shrinks PSU designs

28V synchronous buck power convertor has a wide input range and a programmable 1.2MHz frequency for compact power supply designs.

Available from Semtech Corp, the SC4612 is a 28V synchronous buck power convertor with a wide input range and a programmable 1.2MHz frequency for compact power supply designs.

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 controller runs 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 cross conduction prevention circuitry prevents shoot-through minimising dead time and losses.

"Datacom and server designs face increased power requirements in a limited space and call for a solution like the SC4612 to allow system designers to increase their port density while shrinking board size", said Nejo Necar, Vice President of Marketing for Semtech's Power Management Group.

"The SC4612's synchronous rectified buck topology results in 95% peak efficiency that enables industry leading compact onboard DC/DC convertor designs with 93W/in2 of power density".

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.

The SC4612 is available immediately in production quantities.

Order code for the MPLD-12 packaged device is SC4612MLTRT and is priced at $0.80 each in 1000-unit quantities.

Order code for the SOIC-14 packaged device is SC4612STRT and is priced at $0.93 each in 1000-unit quantities.

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