In this example, a +12 V Fan is decelerating from full speed to 20% speed. During this deceleration, the motor acts as a generator, pumping current back into the supply, causing the supply voltage to surge by 50%, which depending on voltage levels, could easily damage the motor driver. With AVS overvoltage protection enabled, the motor spin down rate is limited, such that the motor never acts as a generator, preventing supply pumping and protecting the motor driver from damage. The tradeoff of this protection is the motor spin down time is increased, which for most fan and small pump applications is acceptable.