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Impedance looks fine but 3.3V is dropping to 0.9V
muthukural001:
Hello All,
In my board, 3.3V rail going down 0.9V. I have one more board that is working fine and impedance of 3.3V on both the boards is same. I am wondering which is causing the voltage drop for 3.3V rail.
Thanks and Regards,
Muthu
aix:
Maybe this is useful?
moffy:
You need to measure the current load. Active devices will only switch on above certain voltages. Feel the components on the board, if one is realy hot then have a look.
muthukural001:
Hi,
I probed 3.3V rail with the oscilloscope and attached the same. As we can see, it is not dropping to 0.9V but going between 3.3V and 2.4V. Also,I have noticed a strange behaviour in my board, I removed the 3.3V sense resistor and connected my multimeter in 10A current mode across the sense resistor. With this setup, I do not see anything like in the image attached, it was a stable 3.3V. The sense resistor is just 20mili ohms and I hav no idea why my board is not working as expected with the sense resistor connected instead of multimeter in current mode. Is there any logic behind this?
Thanks,
Muthu
thinkfat:
What is that sense resistor doing?And how do you think people here will be able to help you if you keep information like this for yourself?
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