User Manual

8. Current sense outputs

The voltages on the M1CS and M2CS pins are each approximately equal to 140 mV per amp of output

current for the corresponding motor. The current sense readings are more accurate at higher currents.

The current sense output pins are designed for PWM frequencies of 5 kHz or higher. If you use a

PWM frequency lower than 5 kHz and want to measure the current, we recommend adding an extra

capacitor between the current sense output pin and GND to smooth out the signal. For example, if

you use a PWM frequency of 490 Hz and want to measure the current of M1, you should add a 1 µF

capacitor (or larger) between M1CS and GND.

Note that while the M1CS and M2CS voltages can potentially exceed 3.3 V at high currents, the

current sense circuit should be safe for use with many 3.3V analog inputs. Most MCUs have integrated

protection diodes that will clamp the input voltage to a safe value, and since the CS circuit has a 10 kΩ

resistor in series with the output, only a few hundred microamps at most will flow through that diode.

8. Current sense outputs Page 33 of 35