Figure 3-3 shows the schematic for configuring the MSPM0G1507 MCU. This reference design uses 10-μF decoupling capacitors (C1 and C2). The GPIO functionality of the MCU is used for PWM generation. One timer instance and the corresponding pins are mapped to the high-side switch PWM. Another timer instance and the corresponding pins are mapped to the low-side switch PWM.

The reference design uses bipolar BLDC control where the high-side switches switching at a high frequency. The low-side switches switch at the electrical frequency of the motor current, which is much lower and the same switches at a high frequency (complementary to high-side switch) during the freewheeling period to enable active freewheeling and hence low losses. All the feedback signal voltages including the input power voltage monitoring, potentiometer voltage for speed control, and temperature sensor output are interfaced to the 12-bit successive approximation (SAR) ADC channels of the MCU.

This design also utilizes the integrated op amp with programmable gain peripherals within the MCU to perform low-side current sensing. This is achieved by inputting the voltage across the sense resistors on the low-side of the three-phase inverter to positive and negative terminals of the one of the op-amp inputs on the MCU (OPA+ and OPA–). This reduces the need for an external current sense amplifier in the design.