ZHCSOD7A February 2023 – September 2023 LM2101
PRODUCTION DATA
To operate power MOSFETs at high switching frequencies and to reduce associated switching losses, a powerful gate driver is employed between the PWM output of controller and the gates of the power semiconductor devices. Also, gate drivers are indispensable when it is impossible for the PWM controller to directly drive the gates of the switching devices. With the advent of digital power, this situation is often encountered because the PWM signal from the digital controller is often a 3.3-V logic signal which cannot effectively turn on a power switch. Level-shift circuitry is needed to boost the 3.3-V signal to the gate-drive voltage (such as 12 V) to fully turn on the power device and minimize conduction losses. Traditional buffer drive circuits based on NPN and PNP bipolar transistors in totem-pole arrangement prove inadequate with digital power because they lack level-shifting capability. Gate drivers effectively combine both the level-shifting and buffer-drive functions. Gate drivers can also minimize the effect of high-frequency switching noise by being placed physically close to the power switch. Additionally, gate drivers can drive gate-drive transformers and control floating power-device gates, reducing the controller's power dissipation and thermal stress by moving the gate-charge power losses into the driver.