High Side Mosfet Driver Pulse Transformer

A gate driver ic can be used to deliver the high currents needed for charging the capacitive mosfet gates.

High side mosfet driver pulse transformer.

For more information see the overview for mosfet and igbt gate drivers product page. A special section deals with the gate drive requirements of the mosfets in synchronous rectifier applications. Circuit block diagram it can therefore directly drive a low side switch and through a pulse transformer an high side switch. Noise immunity negative voltage robustness of the high side driver.

A pulse transformer is an isolation transformer which can operate at speeds often needed for half bridge gate driver applications up to 1 mhz. It has been optimized for both capacitive load drive and pulse transformer demagnetization. The td300 is a three channel mosfet driver with pulse transformer driving capability. High side isolation 600 v is reached within the silicon.

Here s a scope grab showing the pulse from the driver and the voltage on the mosfet side of the transformer. Matched propagation delay between high and low side drive prevents any unbalanced transformer usage. Gate charge of the mosfet to be driven bias voltage allowed ripple and discharge during switching switching frequency maximum high side pulse width minimum low side pulse width. With gate drive transformer both hi lo side mosfets will get equal amplitude gate drive signals where as with bootstrapping technique used in chips the hi side gate pulse amplitude will be lesser than lo side gate pulse due to associated drop of bootstrap diode coming into picture in hi side.

Procedure for ground referenced and high side gate drive circuits ac coupled and transformer isolated solutions are described in great details. The yellow trace shows the voltage drop when the mosfet turns on and then when it closes the voltage climbs again and oscillates.