Drain current zero body diode conduction, Operation – Diodes ZXGD3101N8 User Manual
Page 5
ZXGD3101N8
Document Number DS31945 Rev. 1 - 2
5 of 14
June 2010
© Diodes Incorporated
ZXGD3101N8
A Product Line of
Diodes Incorporated
S Y N C H R O N O U S R E C T I F I E R C O N T R O L L E R
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