Not getting the full output from pins


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  1. #1
    Join Date
    May 2011
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    Default Re: Not getting the full output from pins

    I didn't pull it off the board but I did set up an identical circuit on a breadboard and found the following:
    Two pins together does power the relay but it sounds like a very lethargic actuation. It isn't as snappy of a sound as a relay with the other uCs.
    A pin without relay does output 3.2V
    When the pin is connected to the relay the relay is only drawing (or being supplied) 10 ma and the voltage drop is 1.8ish
    The relay draws 17 ma when connected to the power supply.

    It does appear for some reason the PIC cannot supply enough current for the relay. It is puzzling me because it is well within the PIC's capability and the other two PICs I have power it just fine.

    I am inclined to just use a 1320 for the application but it leaves me wondering what I am doing wrong with the 1827.

  2. #2
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    Default Re: Not getting the full output from pins

    I have also tried it with a 12HV615 at 3.2 volts and it works.

  3. #3
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    Default Re: Not getting the full output from pins

    What's the part # of the relay?
    Regards,

    -Bruce
    tech at rentron.com
    http://www.rentron.com

  4. #4
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    Default Re: Not getting the full output from pins

    What's the DC resistance of the relay coil?

  5. #5
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    Default Re: Not getting the full output from pins

    The coil resistance measures at 180 or 181 among three of them. The datasheet is here:
    http://panasonic-denko.co.jp/ac/e_do...txs.pdf?via=ok
    The p/n is TXS2-3V

    I have tried pins most of the pins to no avail.

  6. #6
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    Default Re: Not getting the full output from pins

    Most devices sink current much more readily than they source current. My guess is that if you connected the + side of the relay to 3.3V and the - side to your PIC pin, the PIC would drive the relay perfectly.
    Charles Linquist

  7. #7
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    Default Re: Not getting the full output from pins

    And here is some proofName:  PicOutput.jpg
Views: 853
Size:  142.5 KB
    Charles Linquist

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