Problem with SN754410


I’m currently develloping an application for a teach-robot. For this I’ve acquired 4 Pololu Dual Serial Motor Controllers kits.
Recently 2 of the SN754410’s have been damaged with no apparent reason. They suddenly short out the power supply (current limit) and I can only hear a high pitched wissle tone. I think it’s coming from the motor but I’m not shure. Exchanging the SN754410 wil fix the problem, but that’s getting costly.

The Motors i’m using are 17 volt 300mA and I’m using a stabilized power supply with the current limit set to 500mA.
All of this is within the operating limits of the SN754410 but still they die :frowning:
The SN754410’s that have failed are not on the motors with the heaviest load and they seem to work fine for day’s or even week’s (not in continuous operation but while developing).

Does anyone have any ideas on this :question:

I am currently waiting on delivery of some spare SN754410’s because i’ve herd they can be “Piggy-Back-ed” to doubel the power ratings. Is this a good idea or are there other valid solutions to the problem?

Kind regards,


I’ve had good experiences with the SN754410, and I don’t remember them being particularly fragile. Can you look at the power supply with an oscilloscope? Perhaps there are some voltage spikes on it. Also, what rating of the motor is 300 mA? If that’s the no-load current, you might be drawing a lot more when there is a load, in which case stacking two of the motor drivers could be a cheap solution.

- Jan

Hi Jan,

Thanks for your reply.

I’ve looked at the supply voltage and there is a lot of noise on the line when the motors are runnen. I think this is caused by the induction currents due to the PWM on/off modulation. I could not find any perticular high spikes but that does not mean they are not there. I do not have a memory scope so these could be hard to find.

I’ll try to solder two SN754410’s together hoping this will fix the problem.
Do you know if the chip has a thermal shutdown feature or does it require specific cooling in this configuration?

Thanks again!!

Kind regards,

The datasheet says the part has thermal shutdown.

- Jan