High-voltage isolated bias power supply circuits have a high-voltage battery as a power source in HEVs and EVs. As a high-voltage battery, 400V and 800V voltage batteries are the most common in HEVs and EVs. The isolated bias supply connected to the high-voltage battery needs to support a wider input voltage range. The need for wide input voltage range support is similar to the low-voltage battery: SOC and load dump scenarios of the high-voltage battery. Based on the SOC of the battery, a wider input voltage range needs to be supported. For example, commonly considered voltage ranges are 240V–450V for a 400V battery and 550V–950V for an 800V battery. However, this voltage range can be different depending on the OEM requirement.

Although the high-voltage battery can be used as a primary source for isolated bias power supply, mostly the battery is used to provide redundancy. Flyback topology is usually selected for such a high and wide input voltage range from a technical perspective as well with respect to minimizing costs.