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I am working on a brushed motor quadcopter. It is powered by a 3.7V LiPo Battery. I have an ESP32 microcontroller which sends PPM signal to a SP Racing F3 EVO Brushed flight controller. The 3.3V to the ESP32 are provided by a LDO regulator(MCP-1700-330) and the flight controller board is powered directly by the same battery. The issue I am facing is that when the brushed coreless motors start running the ESP32 resets(via Brownout Detection). I read similar threads which suggested using large valued capacitors at the regulator input/output else using separate power supplies. In my case I did try large capacitors(470uF) at the input of the regulator but the ESP32 still reseted. And it is not possible for me to use a separate power supply. Please help me as to how I may solve the issue.

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You must make sure that the motors do not drain your capacitor. Try adding a (Schottky) diode before the LDO and put the capacitor after the diode and before the LDO:

schematic

simulate this circuit – Schematic created using CircuitLab

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    \$\begingroup\$ I tried a Schottky diode (BAT85) and a cap(470u) in the configuration you suggested. Now no reset occurs when the motors spin till 50% duty cycle(PWM) but beyond it the controller resets. What may I do? Will increasing capacitance work? \$\endgroup\$
    – Soham
    Mar 25, 2020 at 6:57
  • \$\begingroup\$ You could try but you might have an inherent power problem. Meaning there may be no simple solution. \$\endgroup\$
    – Oldfart
    Mar 25, 2020 at 20:34

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