SLAU927B June 2024 – November 2024 MSPM0G3507
Protecting the power supply from drawing higher current or potential voltage overshoots is important in battery operated applications or applications that do not have an internal overcurrent or overvoltage protection built into the power supply.
Step 1: When the load on the motor increases, the device draws higher current from the power supply. To limit the current drawn from the power supply, enable bus current limit [BUS_CURRENT_LIMIT_ENABLE] and configure the bus current limit [BUS_CURRENT_LIMIT] to protect the power supply from drawing higher current.
For example, limiting the current drawn from power supplies such as batteries is required because the battery life depends on the charge and discharge cycles. Enabling the bus current limit limits the power supply current by limiting the speed of the motor.
Step 2: When a command is issued for the motor to decelerate, based on the deceleration rate, energy from the motor can be pumped back to the power supply, increasing the supply voltage to levels that are possibly unsafe for electronics. Enable the antivoltage surge [AVS] to protect the power supply from voltage overshoots that override any deceleration limit set by any other register and automatically apply a safe deceleration rate.
Figure 7-3 shows overshoot in power supply voltage when AVS is disabled. Motor decelerates from 100% duty cycle to 10% duty cycle at a deceleration rate of 70000Hz/s. Figure 7-4 shows no overshoot in power supply voltage when AVS is enabled.