TPS2412 residue voltage

David Woo

Other Parts Discussed in Thread: TPS2412

Our customer found that there is some residue voltage on Oring controller TPS2412 pin A. VDD is powered from 12V bus.

The test condition is two PSUs in parallel and only peer PSU has 12V on the bus, the local PSU is shutdown but it has about 2.5V on 12V_pre_oring. With remove this IC, no such residue voltage on 12V_pre_oring.

Could you help to comment the reason of this symptom? Any method to fix it?

over 7 years ago

0 Brian Daugherty over 7 years ago

TI__Expert 5940 points

Leakage path on TPS2412.pdfDavid,

The TPS2412 will have leakage current from C to A of up to 10uA. A small load on the front end of ~ 5.11k should be enough to bring to acceptable levels. Try this with the customer and let me know how it behaves.

Brian

0 David Woo over 7 years ago in reply to Brian Daugherty

TI__Prodigy 530 points

We have tried to put a 1k resistor, the level is about 1V. it seems that large load is required. Any further comment?

0 Brian Daugherty over 7 years ago in reply to David Woo

TI__Expert 5940 points

David,

1mA is more than I expected. Discussed with IC designer, more than he thought also. I will get an EVM this week and look at. May be Friday before I get the board and check. Will let you know.

Brian

0 David Woo over 7 years ago in reply to Brian Daugherty

TI__Prodigy 530 points

Brian,

Any good news?

0 Brian Daugherty over 7 years ago in reply to David Woo

TI__Expert 5940 points

Hi David,

Thanks for the patience. I should have a board by tomorrow to test. Waiting for it still.

Brian

0 Brian Daugherty over 7 years ago in reply to Brian Daugherty

TI__Expert 5940 points

David,

I measured similar to you. PSU#1 power applied, PSU#2 off. Vdd for each tied to output (C) Load. Measurement on PSU#2 "A" :

Open circuit = 9v

10k = 6v

1k = 1.1v

And some old data we dug up shows this is bi-directional. See attached pdf. Leakage path shown with a parasitic diode and voltage follower FET biased at ~ 2.5v gate to A. So current is not constant depending on V A and V C conditions.

TPS241x Leakage Path_Measurements.pdf

Brian

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TPS2412 residue voltage