TB6612FNG Dual Motor Driver Carrier problem

This has been puzzling me for a while too. L298 and SN75440 designs are required to have external diodes to deal with back-EMF, and people seem to use physically large ones ( dfrobot.com/image/data/DFR0004/Layout.pdf ). The TB6612FNG like the L293D has internal diodes but the size disparity makes me wonder about on-die diodes. The sparkfun discussion on the SN75440 has the dry remark:

I’m abusing/wasting motor controllers a different way right now (uh, PC fans; doing a single high-side drive per channel through an RC filter, so I have my own problems and suspect I need to clamp at least once externally.) But for people using the H-bridge the right way, yet under somewhat abusive testing conditions, would external diodes be worthwhile, or as useful as racing stripes, or somehow harmful?

Hm. Should I stop using the 9v transistor battery as a test supply for small loads? (EDIT: yeah, in the FAQ that they probably won’t work for real motors, but it doesn’t say “don’t”.)

BTW, don’t feel compelled to say anything about my app; “I bet you’ll be ordering another controller shortly” is as fine response as any. If I expected a design service I’d pay for it. :slight_smile: