In lower voltage FOC applications, many gate driver or motor driver devices integrate up to three current sense amplifiers with programmable gain, which offloads analog requirements from the MSPM33 device. MSPM33 devices without analog integration are available in packages as small as 48-VQFN and 64-LQFP to reduce system size and provide low cost. MSPM33 can accurately sense the motor phase voltage, bus voltage, current, and speed quickly to provide feedback to the FOC algorithm using 12-bit simultaneous sampling 4-MSPS ADCs. This topology is designed for FOC applications that are low-cost and small form factor, such as pumps, fans, blowers, and small appliances.

As shown in Figure 5-3, the signals used this system topology are:

• Six PWM signals with adjustable deadband (6x PWM)
• Logic-low fault signal from driver (nFAULT)
• ADC current sense feedback from integrated or external current sense amplifiers to measure motor phase current, and bus sense voltage
• Optional SPI read/write interface (for drivers with SPI interface)

Figure 5-3 Block Diagram for Sensorless FOC for BLDC Motors using MSPM33C321A and 3-Phase Gate or Motor Driver with Optional CSA and MOSFET Integration