The ISO5851 is an isolated gate driver for power semiconductor devices such as IGBTs and MOSFETs. It is intended for use in applications such as motor control, industrial inverters and switched mode power supplies. In these applications, sophisticated PWM control signals are required to turn the power devices on and off, which at the system level eventually may determine, for example, the speed, position, and torque of the motor or the output voltage, frequency and phase of the inverter. These control signals are usually the outputs of a micro controller, and are at low voltage levels such as 3.3 V or 5 V. The gate controls required by the MOSFETs and IGBTs, on the other hand, are in the range of 30 V (using a unipolar output supply) to 15 V (using bipolar output supply), and need high current capability to be able to drive the large capacitive loads offered by those power transistors. Not only that, the gate drive needs to be applied with reference to the Emitter of the IGBT (Source for MOSFET), and by construction, the emitter node in a gate drive system may swing between 0 to the DC bus voltage, that can be several hundreds of volts in magnitude.

The ISO5851 is thus used to level shift the incoming 3.3-V and 5-V control signals from the microcontroller to the 30 V (using a unipolar output supply) to 15 V (using bipolar output supply) drive required by the power transistors while ensuring high-voltage isolation between the driver side and the microcontroller side.