ZXGD3101N8

Document Number DS31945 Rev. 1 - 2

5 of 14

www.diodes.com

June 2010

© Diodes Incorporated

ZXGD3101N8

A Product Line of

Diodes Incorporated

SYNCHRONOU S R E CTIFIER CONTROLLER

Operation

Normal Operation

The operation of the device is described step-by-step with reference to the timing diagram below.

1. The detector monitors the MOSFET Drain-Source voltage.

2. When, due to transformer action, the MOSFET body diode is forced to conduct there is approximately -0.6V on the Drain pin.

3. The detector outputs a positive voltage with respect to ground, this voltage is then fed to the MOSFET driver stage and current is sourced out of

the GATEH pin.

4. The current out of the GATEH pin is sourced into the synchronous MOSFET Gate to turn the device on.

5. The GATEH output voltage is now proportional to the Drain-Source voltage drop across the MOSFET due to the current flowing through the

MOSFET.

6. MOSFET conduction continues until the drain current reaches zero.

7. At zero current the detector output voltage is zero and the synchronous MOSFET Gate voltage is pulled low by the GATEL, turning the device

off.

Drain

current

zero

Body Diode

Conduction

MOSFET

Gate Current