lossy Schottky rectifiers in power supplies replaced

In a bid to increase power density and improve efficiency, Diodes Incorporated has launched its ZXGD3113 synchronous rectifier controller.

When coupled with a MOSFET, Diodes explains that the pairing can be used to replace lossy Schottky rectifiers in power supplies based on a flyback or resonant converter topology.

The ZXGD3113 controls an external MOSFET, such as the 100V 16mΩ N-channel DMT10H015LPS, configured to operate as an ideal diode. The idea is that this alternative combo can increase efficiency of AC-DC power supplies targeting industrial, consumer and telecommunications markets and negate the need for a heatsink.

According to Diodes, the smaller form-factor SOT26 reduces the solution size from the industry-standard SO8 and by operating up to 250kHz, the PSU designers can use smaller transformers.

Providing the control to a low RDS(on) MOSFET, the ZXGD3113 is designed to achieve greater efficiency by using proportional gate drive. This is said to enable it to rapidly turn off the synchronous MOSFET when operating in continuous conduction mode, although it can also operate in discontinuous conduction mode and critical conduction mode.

Other features include a low threshold voltage of less than 10mV, enabling the control of low RDS(ON) MOSFET and peak source/sink currents of 1.5/3A, respectively, to support efficient driving of the synchronous MOSFET.

Diodes concludes that an operating voltage of 3.5V to 40V means the device can be driven directly by a PSU output as low as 3.5V, while giving sufficient headroom to handle overvoltage spikes or operate at higher VCC rails such as 24V.

Bethan Grylls