Step up/Step Down Regulator

I just hooked up a step up/step down voltage regulator and before I could put a multi-testor on it, it went up in a puff of smoke. I had battery voltage 7.4V on Vin, Ground from the battery, and Vout was connected to pin 8 of a SN754410 that was not hooked up to any load.

Before I got the voltage regulator, I tested the SN754410 circuit with pin 8 connected directly to an 11.1V battery and it worked fine so I do not think it is a problem with my circuit. In this case, there was no motor even hooked up. I did turn the trimpot all the way to the right before I did anything, since I wanted 12V.


I am sorry to hear you are having trouble with your regulator. How long are the leads between your battery and the regulator? Is it possible you might have ever accidentally connected the battery backwards? Doing this could have damaged the regulator, as it does not have reverse voltage protection. Note that we test each board before it ships, so the regulator should have worked at some point.

I am not sure what type of motor you want to drive with your SN754410, but note that the S8V3A regulator can typically only provide about 150 mA when outputting 12 V, as a graph on its product page shows, so it’s very likely your motor will draw more current than the regulator can supply.

- Kevin


Thanks for your reply. The leads to the battery are about 8" total, 4" on the battery and 4" on the control board. I am using a Dean’s ultra connectors that cannot be connected in reverse. I am not trying to run a motor directly from the regulator, but a discrete H-bridge of high power MOSFET transistors. I just need to supply the 12V to the SN754410 so I can have >10V output to drive the gates of the MOSFETs. My statement about not having the motors hooked up is really irreverent. I tested current on the gates in a steady state using a 11.1V battery and I measured <10mA.


Hello, Tracy.

Please contact us directly with your order information to discuss a replacement.

- Kevin