Pololu Robotics & Electronics
Menu
My account Comments or questions? About Pololu Contact Ordering information Distributors

Pololu Forum

Determining capacitor loc/value

So I guess this is a broad question but how can I know where to place capacitors/know capacitor values?

For example, I’m making a PCB that’ll be powered by a 12V LiPo battery (screw terminal), in which I’ll have 2 TB6612FNG drivers, a 5V 2A voltage regulator in which a few components would be LED strip, servo, Bluetooth module, DF Player module.

I tried looking at the motor driver schematic to see if capacitors are needed, but I kinda got confused on one of the diagrams. So I guess any suggestions on where to place capacitors/capacitor value or even how to determine these on my own would be great.

Hello.

Generally extra capacitors are not necessary to use that driver, but your margin with the maximum voltage of the TB6612FNG is pretty tight. (A charged 3S will have a voltage of 12.6V, and the maximum voltage rating for that driver is only 13.5V.) My first recommendation would be to use a motor driver that has a higher maximum voltage rating; for example, you could use a few of our DRV8801 carriers. (Keep in mind each DRV8801 only has one channel.)

You might be able to use the TB6612FNG if you add some extra capacitance near the input (probably something in the few dozen to few hundred microfarad range). However the specific amount you need will depend on many details of your setup, so if you go that route I suggest doing looking at your setup with an oscilloscope to figure out what you need.

By the way, you might also find this Understanding Destructive LC Voltage Spikes document useful.

- Patrick

1 Like