I trying to build a circuit to control the motor using the microcontroller, supplied by the battery that is rechargable. I identified the some of the components i.e. Battery PMIC, LDO, Motor Driver and Microcontroller. And also sensor and switch as additional controls.

My idea is connect these components is as shown in the figure below.

enter image description here

Kindly suggest if there is any other components required to be added or changes to make this possible.

I really wanted to know if I am on the right path to design such a system.

  • \$\begingroup\$ Seems about right. You might find that you need to make changes, once you actually start designing the electronics. For example, maybe your favourite microcontroller outputs the wrong voltage for your favourite motor driver IC, so you need a level shifter. You won't find that out until you know which microcontroller and motor driver IC you're using. \$\endgroup\$
    – user253751
    Jul 14, 2020 at 15:14

1 Answer 1


If the battery is Lithium, the PMIC must sense battery output current as well as input current to avoid excessive time during CV to allow cutoff while supply power directly to motors with a near full-charge. Beware of hysteresis requirements for this. The time at CV duration ages the battery faster than CC. Continued charging at CV while using the charge for the load instead will degrade the battery more rapidly. The same method is used in a Laptop but that device does not have the same wide range in load currents.

If the power is on all the time, an ideal SoC for battery longevity is 60~70% and not 100% and thus cycle in this range instead. Some Lenovo laptops do this.

For defining heat loss, it is wise to estimate impedance.

  • the Motors will have a range of DCR values or Locked Rotor currents
  • the battery will have a range of ESR's from new fully charged to 0% SoC and 10% SoC but expired (reduced capacity)
  • PMIC will thus have a range of loads, voltages and currents for each state to determine SoC and health of the battery. You may want to program some fault detection conditions to include: battery health or Over-current, over-voltage protection, detection, locked-rotor.

For Motor Control IC's look at the ROHM catalog.


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