Power Electronics

Secondary Side Synchronous Regulator

The new SC4901 from Semtech Corp. is a secondary side synchronous regulator that can convert a transformer secondary voltage into multiple regulated dc outputs. The SC4901 is based on Semtech's breakthrough Combi-Sync technology, which enables this secondary side controller to combine synchronous rectification and synchronous post-regulation for isolated outputs.

The SC4901 is a single-chip solution that eliminates the need for point-of-load regulators and primary side controllers in isolated power conversion applications such as voltage regulator modules, power converter bricks, and power supplies for telecommunications and networking applications.

The SC4901 is self-biased from the transformer winding and also uses the transformer signal to create all of the timing functions necessary for regulation. No external bias synchronizing or drive signals are required. The SC4901 drives a back-to-back MOSFET combination that increases power conversion efficiency by eliminating the in-series rectifier diode that is the industry norm.

The SC4901 can operate from a simple square wave input, thus eliminating the need for a primary side regulator and the supporting circuitry across the isolation boundary. In addition, it can generate multiple regulated output voltages from a single transformer winding thus simplifying the design.

The SC4901 device operates over an input voltage range of 4.5 V to 18V and can operate at speeds up to 1 MHz. The device is available in a low-profile, 16-pin TSSOP package.

For more information, visit www.semtech.com.

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