ISO5451

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SLLSEO1B – JUNE 2015 – REVISED DECEMBER 2015

10 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

10.1 Application Information

The ISO5451 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 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 swings between 0 to the DC bus

voltage, that can be several 100s of volts in magnitude.

The ISO5451 is thus used to level shift the incoming 3.3-V and 5-V control signals from the microcontroller to the

30-V (using 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.

10.2 Typical Applications

Figure 41 shows the typical application of a three-phase inverter using six ISO5451 isolated gate drivers. Three-

phase inverters are used for variable-frequency drives to control the operating speed of AC motors and for high

power applications such as High-Voltage DC (HVDC) power transmission.

The basic three-phase inverter consists of three single-phase inverter switches each comprising two ISO5451

devices that are connected to one of the three load terminals. The operation of the three switches is coordinated

so that one switch operates at each 60 degree point of the fundamental output waveform, thus creating a six-

step line-to-line output waveform. In this type of applications, carrier-based PWM techniques are applied to retain

waveform envelope and cancel harmonics.

Figure 41. Typical Motor Drive Application

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