Gate Drive Transformer Tutorial

Procedure for ground referenced and high side gate drive circuits ac coupled and transformer isolated solutions are described in great details.

Gate drive transformer tutorial.

These devices provide electri cal pulses for turning on and off semiconductors such as high voltage power mosfets or igbts. This gate drive transformer gdt circuit allows the drive signal to the mosfet to range from 50 down to 0 while still offering a fast turn off that cannot be accomplished with a simple load. Designed is the gate drive transformer in a switch mode power supply smps. Gate drive ics the simplest way to drive a gate is to use a gate drive ic.

The gate drive transformer provides both the floating supply as well as the level shifting of the switching signal to the power semiconductor thereby eliminating a separate floating power supply. They also are used for voltage isolation and impedance matching. This ic contains the necessary circuitry to source and sink high current pulses and usually simply requires a power supply and a logic level input. Large duty ratios more than 50 cannot be handled by the transformer without being saturated due to the transformers operating only at ac signals the core flux must be reset each half cycle in order to maintain a volt second balance unless ac coupling capacitors and zener diodes are employed.

A gate drive transformer isolates the controlling gate drive circuit from the switch node when driving the mosfet gate and may also scale the output voltage via an appropriate primary to secondary turns ratio. It can be used to directly drive the power switch mosfet igbt gates or it can be used to just isolate the control signal which is then applied to a gate driver ic. A gate drive transformer is needed in a smps to control the timing of the circuit. The larger ones may come in a 5 pin to 220 package.

For more information see the overview for mosfet and igbt gate drivers product page.