We have introduced a smart-gate driver coupler (the TLP5222, TLP5212, TLP5214A and TLP5214) with built-in VCE(sat) detecting and Miller clamping functions to protect the IGBT from being damaged by overcurrent. The VCE(sat) detecting function monitors the VCE(sat) voltage of the IGBT and soft-turns off the photocoupler output when an overcurrent occurs. At the same time, FAULT signal is sent to the controller. The Miller clamping function suppresses gate potential rise and IGBT malfunction by bypassing the Miller current generated when the IGBT is turned off to ground via the inside of the photocoupler. The TLP5222, TLP5212, TLP5214A and TLP5214 also integrate a number of other functions, including full-swing-voltage outputs and UVLO functions. Reducing the number of external components that have supported these functions has been effective in reducing costs and reducing the size of PCBs.