I am building a small robot with the metal geared micro motors from pololu. I have measured them to draw 80mA when running free and 1.6A when stalled (at 6V). The driver I have is a TB6612FNG. I have learned that to make this more or less fool proof, with a motor driver generally one needs back EMF protection and some mechanismo to avoid that a stall blows the driver or motor. As far as I can tell this driver has already 4 diodes for each channel build in, so I got back-EMF if I understand that correctly:http://www.sparkfun.com/datasheets/Robotics/TB6612FNG.pdf
However, the peak output rating is 3.2A only for a few ms, so if some kid holds the wheels of my robot - and they will do so
- I would like a mechanism to avoid burning the driver/motor. I first thought about a resettable fuse, but they seem to be too slow (not in the ms range). Should one simply put a resistor R_L in series with the motor (say to limit current to 0.5A at 5V we need 10 Ohms with a rating of 2.5W, right?) or is there a more clever method to do this (something like detecting too much current by measuring the voltage drop on R_L and setting the driver to standby mode)? I would like this do be done by hardware, if possible.
Any suggestions? Or maybe another driver, that has such a protection built-in? Should be cheap ....