TPS2065D: reverse current at OTG conditions

Hi Muk,

The internal structure is back to back Mos.

With IN=0 or EN pulled down to GND, reverse current should be blocked.

For TI's policy, I will first click resolved button.

If you have any other concern, contact me any time.

If you think resolved, please help click 'Issue is solved button'.

Thanks.

Hi Zhang-san,

I understood your comment about internal back to back mosfet.

However, The following waveform has reverse current at Vin=0V, EN=0V and Vout=5V.

Could you please let me know the reason of this waveform?

Thanks

Muk

Hi Muk-san,

Have you removed the output cap of the IC?

I think it's transient current which comes from charging output cap.

For TI's policy, I will first click resolved button.

If you have any other concern, contact me any time.

If you think resolved, please help click 'Issue is solved button'.

Thanks.

Hi Zhang-san,

The following waveform at removed IC(The output cap is mounted).

We cannot find the reverse current on this waveform. So, I think, it is not depended on charging output cap.

Regarding the following waveform at IN=5V, EN=0V.
We cannot find the reverse current on this waveform.

If the reason is output capacitor, I think, it should have the reverse current on this condition.

Thanks

Muk

Hi Muk-san,

What's Isys?

Any possible to remove this line to have a test?

Hi Muk-san,

I think it may be related to output discharge function.

I have requested the sample on ti store.

Will have a test for you.

But before that, you can have a study about the output discharge function.

For TI's policy, I will first click resolved button.

If you have any other concern, contact me any time.

If you think resolved, please help click 'Issue is solved button'.

Thanks.

Zhang-san,

Thank you for your supporting.

We wait your test results.

Thanks

Muk

Sure.

Zhang-san,

Do you have any update?

Thanks

Muk

Muk-san,

The IC has not been arrived.

Will update accordingly.

Thanks.

Hi Muk-san,

Sorry for the delay response.

Below is the test result on TPS2065D EVM board.

VIN=0V(connect to GND or floating), EN connect to GND, for Vout=5V.

Measure Iout.

As you can see from the waveform, the output current is about 100mA which is transient . I think it's the current from the output cap.

As I remove the output cap, it's easy to damage the part.

I want to confirm whether the current you tested is transient or constant?

Please also confirm whether the IC is normal or abnormal as you test.

Hi Zhang-san,

>I want to confirm whether the current you tested is transient or constant?

Transient current (peak : around 1A)

>Please also confirm whether the IC is normal or abnormal as you test.

IC is normal. because it can reproduce this issue with another sample.

Also, customer tried to replace TPS2065(null). Then, They didn't find this issue.

TPS2065 don't have discharge function. we believe the reason of this issue is discharge function.

Could you please give me your comment for it?

Thanks

Muk

Hi Muk-san,

I test several pieces again.

1.With Cout=150uF+0.1uF, VIN short to GND or Open, EN short to GND, measure Iout=200mA.

2. With Cout=0uF, VIN short to GND or Open, EN short to GND, measure Iout=0mA.

It can be seen that the reverse current is from the output cap.

Please double confirm your results.

For TI's policy, I will first click resolved button.

If you have any other concern, contact me any time.

If you think resolved, please help click 'Issue is solved button'.

Thanks.

Hi Zhang-san,

Could you please let me know the root cause for this current?

Why does it increase at adding output cap?

> Is This current the charging current to output capacitor from EVM output 5V?  is it meaning, the IC don't have reverse current?

Thanks

Muk

Hi Muk-san,

1. I think the reverse current is due to the LC oscillating where L is from the cable wire and PCB wire. As with step voltage, the output cap is sure to have irush current.

2. The test condition is disabled and VIN=0V, it will not have the reverse current but several micro-ampere leakage current as shown in datasheet spec.

For TI's policy, I will first click resolved button.

If you have any other concern, contact me any time.

If you think resolved, please help click 'Issue is solved button'.

Thanks.

Hi Zhang-san,

Thank you for your answer.

Customer didn't find the reverse current when they removed IC with same board.

Also, They didn't find the reverse current when they used TPS2065(null version) with same board.

How should I explain about this behavior?

Thanks

Muk

Will reply to you today.