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Author Topic: ULQ2003A driver issues  (Read 11737 times)

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Offline calexanian

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Re: ULQ2003A driver issues
« Reply #25 on: May 13, 2015, 10:28:42 pm »
Your common freewheeling diode pin should be tied to the supply voltage of the load. In this case 12 volt supply of your buzzer or whatever you have. Also with these make sure your MUC output is actually pulled low and not just tristate high. You may need to add pull down resistors. 
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Charles Alexanian
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Online wraper

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Re: ULQ2003A driver issues
« Reply #26 on: May 13, 2015, 10:59:14 pm »
Quote from: calexanian on May 13, 2015, 10:28:42 pm
You may need to add pull down resistors.
There are pull downs inside of the ULQ2003A.
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Offline cio74Topic starter

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Re: ULQ2003A driver issues
« Reply #27 on: May 13, 2015, 11:27:19 pm »
Found the problem, one PCB has LittleFuse TVS and the other AVX brand. Removing the AVX diode cured the issues.

Not all TVS are made the same...
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Offline calexanian

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Re: ULQ2003A driver issues
« Reply #28 on: May 14, 2015, 06:05:58 pm »
Quote from: wraper on May 13, 2015, 10:59:14 pm
Quote from: calexanian on May 13, 2015, 10:28:42 pm
You may need to add pull down resistors.
There are pull downs inside of the ULQ2003A.

Sorry. Cobwebs in the brain. My brain went to VQ1000 chips for some reason. Another until recently discontinued driver chip. I should have been more on top of it because we use ULN2803's here in mass quantities and it is a similar driver chip. I think as my beard turns grey its pulling the smarts out of my brain, and i did not have much to start with!
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Charles Alexanian
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Offline jeff.remus

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Re: ULQ2003A driver issues
« Reply #29 on: May 16, 2015, 10:48:49 am »
Flux under the IC?
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