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How to reduce circuit current consumption

Discussion in 'General Electronics Discussion' started by paddy, Apr 20, 2014.

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  1. paddy

    paddy

    81
    0
    Sep 11, 2012
    Hi,

    I am using XTR 117 for two wire transmitter design. Please refer attached schematic.

    Everything working fine except current consumption of the circuit. The total current consumed by circuit is around 7mA. Because of that I am not able to achieve the 4mA output.

    I have implemented same schematic couple of months back and the results was good at that time. The current consumption was less than 3 mA.

    The only difference is, earlier I have used DIP components for prototype and now used all SMD components.

    Please have a look on schematic and bill of material and suggest what I need to do to reduce the current consumption of the circuit.

    Thanks,

    paddy
     

    Attached Files:

  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,418
    2,788
    Jan 21, 2010
    The first thing to do is to determine if you have excessive power consumption due to a wiring error.

    If you can exclude that, then determine if any one chip in particular is drawing excessive current. Perhaps you have an out of spec component, or one that was damaged.

    I note you have quite a few zener diodes between the power supply rails and ground. Why? Could one of them be the culprit?
     
  3. paddy

    paddy

    81
    0
    Sep 11, 2012
    Thanks Steve for your prompt reply.

    The zener diodes are connected for over voltage protection.

    The excessive current consumption is due to capacitors C9 to C12 which are connected at the output of the op amp. Now removed that capacitors and the consumption is below 3 mA.

    Thanks again for your help!!!!

    Regards,
    Paddy
     
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