Low power design current leakage issues

I build a lot lot of low power designs and what I have confronted is that the circuit that I have has micro Amp current consumption when on the breadboard when the Micro sleeps along with other sensors also sleep VS. when I build the PCB for it the almost the same circuit burns 20times more current.

for example my microcontroller project is developed on the breadboard with the same set of sensor development boards, it takes 50uA and then I build the same circuit on PCB and it takes 850uA.

My current measurement device is really accurate being a EEVBlog uCurrent connected to a Fluke 87.
I'm sure my chinese factory is assembling the boards with some high ESR/ESL capacitors.

as such what you guys suggest I should do? and are there any other factors that are worth looking into which might be eating all that power for FREE :o ?!

Something oscillating that shouldn't be?

If you suspect the capacitors, replace them.

if you use groundplanes/powerplanes, be sre you have plenty of room around via and holes etc.
measure resistance of a pcb withoyt components, does it have a soldermask.
and many more influences, like capacitance, noise on the power supply, etc.

shooter:
if you use groundplanes/powerplanes, be sre you have plenty of room around via and holes etc.
measure resistance of a pcb withoyt components, does it have a soldermask.
and many more influences, like capacitance, noise on the power supply, etc.

I have 1.27mm spacing around(GnD Plane) the via. drill and other pth drills or smd pads which I consider good spacing.

what resistance of the pcb you consider fine? and yes it has a soldermask

everything is very small.

mikb55:
Something oscillating that shouldn't be?

not really, I'm damn sure on that.

jremington:
If you suspect the capacitors, replace them.

Im changing to X7R's which should be 500ohm-farad on leakage, can you suggest some capacitors that are available with less than 1uA leakage from AvX and kemet, I tried searching but the datahseets were vague, should be 4/6 vdc most probably.

Hi,
Are the caps you use on the development board the same caps as on your PCB?

If the caps are different, and the current consumption so important, I'd be putting the PCB caps on the development board and check.
Have you checked the current through a PCB that is not populated?

Tom....... :slight_smile:

Is the breadboard microcontroller programmed exactly the same? I don't mean the Arduino program but maybe there's some fuse settings that are defaulting one of the subsystems (like oscillator or watchdog) in a way that is different to your test system.

Do you have any floating inputs? Tie them to ground or Vcc.

TomGeorge:
Are the caps you use on the development board the same caps as on your PCB?

Have you checked the current through a PCB that is not populated?

Tom,

Yes I use the same caps in terms of Value (hmm.. maybe X7Rs or Y5V dielectric material may fack!!)

hmm,, interesting I didnt check the current through the PCB not populated, I will have to do so.

MorganS:
Is the breadboard microcontroller programmed exactly the same? I don't mean the Arduino program but maybe there's some fuse settings that are defaulting one of the subsystems (like oscillator or watchdog) in a way that is different to your test system.

Do you have any floating inputs? Tie them to ground or Vcc.

Yes the custom PCB system is programmed with the same Firmware as the breadboard one!!

I'm not tying the inputs etc floating to anything physical on PCB, I just configure them with internal pullUp activated.

Are the fuses set the same?
Have you disabled the brownout detection and ADC (335 uA)?

If you put the board in total darkness does the current change?

Hi,

Yes I use the same caps in terms of Value (hmm.. maybe X7Rs or Y5V dielectric material may fack!!)

So, different brand, construction etc, but same value.

You may need to set up a test circuit where you put the relevant DC across the caps and you measure the leakage, comparing what you used in prototype and what you use in PCB.

Or take a populated PCB and measure current as you remove major caps.

Tom.... :slight_smile:

jremington:
Are the fuses set the same?
Have you disabled the brownout detection and ADC (335 uA)?

offcourse!

TomGeorge:
Or take a populated PCB and measure current as you remove major caps.

Tom… :slight_smile:

this is my favorite approach!

What is your choice on least leakage caps? I have always eyed the AvX and Kemet but they are usually very costly and the Samsung may seem as the best bet but their caps perform 2 times less than AvX and Kemet so my supplier of parts suggested me YAGEO MULTICOMP, what you’ll say about it? (offcourse only if you know about this brand at all)

I'd check the polarity of the caps, perhaps one is reversed on the PCB?