In some examples, a controller device is configured to control power electronics circuitry and includes a high-voltage (HV) pin, a power supply (VCC) pin, a startup device configured to conduct electricity from the HV pin to the VCC pin, and comparator circuitry configured to determine whether a voltage level of the VCC pin is greater than a turn-on voltage threshold. In some examples, the comparator circuitry is further configured to cause the controller device to enter a normal-operation mode in response to determining that the voltage level of the VCC pin is greater than the turn-on voltage threshold. In some examples, the controller device also includes level detection circuitry configured to determine the turn-on voltage threshold based on a level of the HV pin.