Part Number:TPS27081A
I was not able to send you an image, I'll try to explain the problem only in text.
On page 1 of the TPS27081 datasheet we can see the p-FET pass transistor (Q1), R1 and C1 (timing network) and the load capacitance (CL).
At power-on, when VIN=3.3V arrives to the TPS27081, C1 and CL are discharged then Vgate of Q1 is kept to 0V until C1 charges (through R1).
But Vsource of Q1 is 3.3V, then Q1 has Vgs = -3.3V and then conducts!
So we have a power switch that conducts just when it must NOT conduct. We have this problem on our board using this device.
Q1 conduction continues until C1 is charged to a level where Vgs falls below the Q1 Vgs threshold.
The problem is visible only when C1 > 22nF. We cannot use 22nF because in this case the switch is so fast that the in-rush current is excessive (5A and more).
The ideal value for us should be 100nF or more, but in this case we obtain the spurious activation described above.
Could you please help us to solve this issue?
In addition, we would appreciate if you can indicate how we can send a PDF file (to show waveforms etc.).
Thank you in advance.
Best regards.