Many gate driver photocouplers have a UVLO (Under Voltage Lock Out) function to prevent malfunction at low voltages. This function stops the output of the coupler until the power supply voltage of the gate driver coupler reaches the UVLO release voltage, such as when the power supply is turned on, and prevents malfunction of the power device during the start-up of the input voltage. When the power supply voltage drops during operation and drops below the UVLO detection voltage, the operation stops.
This function prevents the power device from being underdriven. When the power supply voltage rises and exceeds the UVLO release voltage, the UVLO is released.