power problem ADATA SU900

[fzabkar]

One thing you might like to try is to disable U6 by shorting its enable pin to ground.

Enable

When input voltage is greater than the undervoltage lockout threshold (UVLO), typically 2.3V, MP2162 can be enabled by pulling EN pin to higher than 1.2V. Leaving EN pin float or pull down to ground will disable MP2162.

Then see if the other voltages are stable.

Attachments

Reg_1V5.jpg (110.26 KiB) Viewed 5981 times

Reg_1V5_resistors.jpg (57.05 KiB) Viewed 5981 times

[lasek]

After disabled MP2162 current is still not stable and still changing in every points. I marked capacitors connected to 1.5V point.

Attachments

[fzabkar]

When you grounded the enable pin of U6, did its output remain at 0V? If not, then it must be faulty.

Otherwise I'm out of ideas.

[lasek]

No, after grounded enable pin still showing changing current between 0,1 to about 2,2V but not 0V.

[fzabkar]

Either U6 is faulty, or there is an open feedback resistor. See R1 and R2 in the application circuit.

[lasek]

sorry where is resistor R1 and R2 ?

[fzabkar]

See attachment.

Attachments

Reg_1V5_resistors_feedback.jpg (62.99 KiB) Viewed 5895 times

[lasek]

Thank you fzabkar for your help. Unfortunately I don't resolved this case.

[arvika]

This case probably can be solved, so hope you redirect client to another lab.