Rectifier controller saves board space

February 27, 2018 // By Nick Flaherty
Rectifier controller saves board space
Diodes has introduced a synchronous rectifier controller that can be paired with a MOSFET to replace lossy Schottky rectifiers in power supplies using 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. Replacing a Schottky rectifier with the ZXGD3113+MOSFET can significantly increase the efficiency of AC-DC power supplies targeting the industrial, consumer and telecommunications markets, reducing footprint on the board.

With improved efficiency, this negates the need for a heatsink to save space compared to a lossy Schottky rectifier. Furthermore, 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, further saving space and BOM costs. 

Providing the control to a low RDS(on) MOSFET, the ZXGD3113 achieves greater efficiency by using proportional gate drive, enabling it to rapidly turn off the synchronous MOSFET when operating in continuous conduction mode (CCM), although it can also operate in discontinuous conduction mode (DCM) and critical conduction mode (CrCM). 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. A wide operating voltage of between 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.

The ZXGD3113 synchronous rectifier controller and DMT10H015LPS MOSFET are priced at $0.24 and $0.40 respectively each in 3000 piece quantities

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