I have a circuit that I developed on breadboard. I have then soldered it on a PCB and it is now drawing more current on PCB compared to when it was on breadboard. I only want to discuss possible reasons for this without going into much detail about the circuit as I haven't changed it before or after soldering on PCB unless someone really wants me to.

Details about the circuit:

  • Micro-controller based circuit.
  • A couple sensors and a single radio.
  • Step-up regulator for powering everything (Pololu 5V).

This is what comes to my mind:

  • Flux conducting some current?
  • Possible tiny short-circuit somewhere?
  • Possible faulty chip after soldering?
  • Possible different current consumption with different power supplier? (3.6V lipo battery over a cheap AC 1A 5V adapter)
  • Possible larger resistance on breadboard circuit.

The circuit works fine so I assume there is no problem with PCB.

On breadboard it was drawing about 28.5mA. Now on PCB it's drawing about 40mA.

Thanks everyone.

  • \$\begingroup\$ This is not a discussion forum, sorry. Without specific question there is no specific answer. \$\endgroup\$ – Eugene Sh. Feb 13 '19 at 17:23
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    \$\begingroup\$ This site is structured around having a specific question with a "correct" answer. Without circuit details the question is unanswerable, as there are umpteen possible reasons for the discrepancy, and exhaustively listing these to cover every possible circuit is not reasonable. \$\endgroup\$ – Kevin Kruse Feb 13 '19 at 17:26
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    \$\begingroup\$ You said that the power consumption changed but then you talk about changing current. Which is it? Please explain your manufacturing and assembly process in detail, if you won't describe the circuit. \$\endgroup\$ – Elliot Alderson Feb 13 '19 at 17:27
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    \$\begingroup\$ What do you get for actual power consumption then? What happens if you multiply supply voltage by supply current in both cases? \$\endgroup\$ – Elliot Alderson Feb 13 '19 at 17:35
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    \$\begingroup\$ If you're expecting "an exhaustive answer for possible reasons", then pretty much by definition your question is too broad for this site (and the reason for my close vote), although it looks to me as if JYelton has found your non-issue. \$\endgroup\$ – brhans Feb 13 '19 at 18:02

If you supplied 5V while the circuit was on a breadboard, and 3.6V while it is on a PCB, that seems to me the biggest explanation of different currents. Having no idea what your circuit is, I'll just calculate if it has the same power in both configurations:

Breadboard: \$P = 5 \times 0.0285 = 142.5\mathrm{mW}\$

PCB: \$P = 3.6 \times 0.04 = 144\mathrm{mW}\$

It looks like the device draws the same power so I think you may be seeing a problem that isn't there.

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