ULQ2003A driver issues

• #25 Reply
  Posted by calexanian on 13 May, 2015 22:28
• 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. 
• #26 Reply
  Posted by wraper on 13 May, 2015 22:59
• Quote from: calexanian on 13 May, 2015 22:28

  You may need to add pull down resistors.
  

  There are pull downs inside of the ULQ2003A.
• #27 Reply
  Posted by cio74 on 13 May, 2015 23:27
• 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...
• #28 Reply
  Posted by calexanian on 14 May, 2015 18:05
• Quote from: wraper on 13 May, 2015 22:59

  Quote from: calexanian on 13 May, 2015 22:28

  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!
• #29 Reply
  Posted by jeff.remus on 16 May, 2015 10:48
• Flux under the IC?