An inductive load is any load that stores magnetic energy when connected to a supply voltage. The inductive load impedance consists of both a resistance and inductance in series. Common inductive loads that can be driven by Smart High Side Switches are relays, motors, and solenoids. When they are switched off inductive loads can generate a transient negative voltage of hundreds of volts due to the stored magnetic energy in the inductance. This transient voltage can cause severe damage to the drive circuit. To prevent any potential damage, during switch-off the stored magnetic energy must be dissipated by clamping the voltage across the inductive load. TI Smart High Side Switches integrate a power clamp circuitry that protects the circuit by clamping the voltage over the switch to a set voltage and recirculating the current through the clamp. This causes the stored energy to be safely dissipated. With this large clamp voltage the demagnetization time is decreased leading to a safe and quick turn off time for inductive loads.

This document gives guidance on the important parameters and calculations for high reliability during inductive load driving. Due to the integrated clamp, TI Smart High Side Switches are generally capable of driving an inductive load with no need for external protection components like Transient Voltage Suppressor (TVS) diodes. The section will use the TPS4H160-Q1 as an example for most calculations, but the calculations and comparisons will be very similar with all TI High Side Switches if the demagnetization energy plot is available.

We will start by looking at common inductive load applications followed by deriving the critical parameters and equations that determine the inductive load demagnetization. Then we will begin looking specifically at the TPS4H160-Q1 as a case study for reading a demagnetization energy plot. Finally, we will look at several examples showing specific applications and how we can tell if the TI Smart High Side Switch is capable of demagnetizing the load.