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Hot!My MCP73X23 board went up in smoke with input under 18 volts and 12 volts

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CJ_Chip
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2020/09/21 07:35:10 (permalink)
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My MCP73X23 board went up in smoke with input under 18 volts and 12 volts

I purchased a MCP73X23-LCP evaluation board.  This board charges  LIFEPO4 (Life) batteries..  There are two parts to the board,the  MCP73123 IC which charges a single battery and a MCP73223 IC whch charges 2 batteries.  I connected a barrel connector to the MCP73223 board, positive to the vdd connector and negative to the vss connector.  The transformer (wallwart) was  16 volts/1 amp.  When I plugged it in, the ic (mcp73223) smoked and burnt up.  I checked my connections and the wallwart is a center tap positve, the center of the barrel connector is positive and was connected to vdd.  The barrel was negative and connected correctly.  Even though the data sheet says that it be powered up to 18 volts, I thought my 16 volts (using a volt meter) might be too much.  Then I used my bench power supply.  I set the voltage to 12 volts and connected the red to vdd and black to vss on the mcp73123 side of the board.  Again, the IC smoked and stopped working.  I have included 2 pictures to look at, the first picture is the barrel connector to the mcp73223 side to show the way that I connected the power supply to the board.   The second picture is a picture of my power supply and the voltage that I had applied to the mcp73123 side of the board.  Any ideas why I had problems today?

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    PStechPaul
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    Re: My MCP73X23 board went up in smoke with input under 18 volts and 12 volts 2020/09/22 20:08:25 (permalink)
    4 (2)
    Your pictures are too small to tell very much. Someone else recently had problems with a PCB that exhibited sparks and smoke and short circuit when powered up, and it was determined to be caused by improper cleaning of solder flux. Also, some 16V wall-warts can put out more than 20V when lightly loaded, and some cheap lab supplies can produce higher voltage transients and noise. You might want to solder a 15V zener or TVS diode across the Vdd-Vss terminals, and a series fuse.

     
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    domble
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    Re: My MCP73X23 board went up in smoke with input under 18 volts and 12 volts 2020/09/23 06:00:28 (permalink)
    1 (1)
    I think I agree with the person on the other forum (with the same too-small photos) that the power supply is wired up backwards on the PSU picture?  Corner of the evaluation board with the red clip attached should be Vss, PSU ground, I think.  http://ww1.microchip.com/...n/DeviceDoc/51850a.pdf
    Worth being cautious with the current limit when firing up a new circuit...
    dom.
     
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    ric
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    Re: My MCP73X23 board went up in smoke with input under 18 volts and 12 volts 2020/09/23 13:37:30 (permalink)
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    domble
    I think I agree with the person on the other forum (with the same too-small photos) that the power supply is wired up backwards on the PSU picture?  Corner of the evaluation board with the red clip attached should be Vss, PSU ground, I think.  http://ww1.microchip.com/...n/DeviceDoc/51850a.pdf
    Worth being cautious with the current limit when firing up a new circuit...
    dom.

    What other forum?
    The photo is rotated 180 degrees from the diagram in the instructions.
    The red wire goes to TP4/VDD1
     

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    #4
    CJ_Chip
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    Re: My MCP73X23 board went up in smoke with input under 18 volts and 12 volts 2020/09/26 06:58:56 (permalink)
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    Thank you all for your responses.  I did have it wired up wrong and too much voltage.  I purchased a new board and will try it again with the proper voltage and polarity.  I also purchased new IC's (MCP73223) and will try to repair the smoked boards. 
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    ric
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    Re: My MCP73X23 board went up in smoke with input under 18 volts and 12 volts 2020/09/26 07:27:46 (permalink)
    5 (1)
    Where was the wrong wiring?
     

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    CJ_Chip
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    Re: My MCP73X23 board went up in smoke with input under 18 volts and 12 volts 2020/09/28 19:49:33 (permalink)
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    I got a new board and it works fine!  Thanks to all who responded,
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    CJ_Chip
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    Re: My MCP73X23 board went up in smoke with input under 18 volts and 12 volts 2020/09/28 19:49:33 (permalink)
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    I got a new board and it works fine!  Thanks to all who responded,
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    domble
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    Re: My MCP73X23 board went up in smoke with input under 18 volts and 12 volts 2020/09/29 02:30:11 (permalink)
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    ric
    What other forum?
    Where was the wrong wiring?

    Didn't post the link for fear of the forum firewall... first hit on duckduckgo for MCP73X23-LCP anyway.
    https://www.electro-tech-online.com/threads/lifepo4-battery-charger-mcp73x23-evaluation-board-went-up-in-smoke.159920/
    Looked to me like first photo (with the connector) was ok, second photo (with the power supply) had black and red wires (clipped to the board) reversed.
    #9
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