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Subject:		Re: MOTOR DRIVER CHIP
Name:		Rob
Date Posted:		May 7, 05 - 6:22 PM
Message:		Hi Matt, Sorry to hear you're having problems with the BA chip - I did manage to blow one up myself, so don't think you're alone! I think they're not all that robust and won't stand severe abuse (like short circuiting the o/p's etc) like some chips can. I never had any problems with temperature - they barely got warm in normal use and didn't need a heatsink if you look at the picture. If they are getting that hot and the motor isn't turning I'm afraid to say I think it may be shot - after I blew my first one I replaced it and bought another couple as spares just in case! (Fortunately they are reasonably cheap) Firstly, connect the motor direct across the 12V battery and make sure it turns ok; if you have a multimeter that reads current, take a reading and make sure it isn't drawing more than 1.0A - if it is then you'll have to find some new motors - these two steps should verify that the motor is ok and isn't the source of the problem. To simplify things once you get a replacement, follow the diagram on page 10 (I think) of my report but connect Vref (pin 3) direct to +12V (don't build the LM317 part of the circuit - its just the speed control which we can live without for the moment). Don't connect the motor and don't let the motor output terminals short to each other or +Volts/0V. If you want you could always put a 1.0A quick blow fuse in the +12V which MAY save the IC should the worst happen. Connect the +5V and to Vcc (pin 9) and Fin (pin 10). Tie both the 12V 0V and 5V 0V rails together and connect to GND (pins 1&5) and Rin (pin 2) - this should put the driver into forward drive mode. Turn on the power supplies (5V then 12V) and carefully meter across pins 4 and 7 you should have either +/-12V depending which way round your probes are. Now turn off the power supplies (in reverse order). Connect Fin (pin 10) to GND and Rin (pin 2) to +5V this should put the driver into reverse drive mode and turn on the power supplies (5V then 12V) and carefully meter across pins 4 and 7 you should have either -/+12V depending which way round your probes are but it should be opposite to what you had before providing your probes are connected the same way. If you are now able to get switching and the chip isn't getting hot then try connecting the motor it should hopefully run and you should be able to switch directions. Check all the connections carefully before switching on and make sure there aren't any short circuits or missing links. Now go brew up or watch a bit of TV come back and check them again! Immediately you switch on without the motor connected check that the IC isn't getting warm at all; if it starts to get warm, switch off immediately and check you connections again Don't give up, the most important things are learnt from making mistakes. Let me know how you get on. PS IF I get chance I will draw a sketch of the above, scan it in and give you a web link but it may be 2/3 days before I get chance.
Replies:
Re: Re: MOTOR DRIVER CHIP by MATT · May 8, 05 - 10:05 AM Re: Re: Re: MOTOR DRIVER CHIP by Rob · May 8, 05 - 11:36 AM Re: Re: Re: Re: MOTOR DRIVER CHIP by Rob · May 10, 05 - 9:21 PM

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