TPS62230: Reverse current during shutdown

Dice-K

Part Number: TPS62230

Hi support team,

There appears to be current backflow from the SW pin to the VIN pin during shutdown.
The moment the VIN voltage drops and becomes the same voltage as VOUT, a reverse current of just under 100mA occurs.
Since the EN pin is above 1V, the PMOS remains active, so I suspect that current is flowing from SW to VIN.

(Or is it reverse current through a parasitic diode?
Does it have a backflow prevention function?)

Does this reverse current have any negative effect on the device?

Regards,
Dice-K

over 1 year ago

0 Moheddin Pasha Shaik over 1 year ago

TI__Mastermind 18090 points

Hello Dice,

Thank you for using E2E,

As soon as the VIN of the device reaches UVLO falling threshold, the device stops switching, it means both the FET's does not operate.

The reverse current flowing here might be through the body diode of the HS-FET,

Do you have any external voltage on the VOUT when the VIN is below UVLO?

Can you please share me your schematic and provide me the SW, VOUT & VIN during device shutdown.

Thank you & regards,

Moheddin.

0 Dice-K over 1 year ago in reply to Moheddin Pasha Shaik

Mastermind 7470 points

Hi Moheddin,
Thank you for your reply.

I sent the shematic and waveforms via private message.
Please let me know if you have any problems.

Best regards,
Dice-K

0 Moheddin Pasha Shaik over 1 year ago in reply to Dice-K

TI__Mastermind 18090 points

Hello Dice,

Thank you for sharing the Schematic and waveforms.

Is this the same project as discussed in the below thread?

(+) TPS62230: Reverse input current at start-up - Power management forum - Power management - TI E2E support forums

Can you please share me the zoom-in waveform exactly at the negative current to observe the behavior and duration of the negative current and also can you try with and without diode(D1001)?

Thank you & regards,

Moheddin.

0 Dice-K over 1 year ago in reply to Moheddin Pasha Shaik

Mastermind 7470 points

Hi Moheddin,
Thank you for your reply.

Yes, it's the same project as the previous thread.

I request the customer to zoom in on the negative current waveform.
They removed the diode of D1001 and observed both the output and input currents, but there was no significant change in the results.

Best regards,
Dice-K

0 Moheddin Pasha Shaik over 1 year ago in reply to Dice-K

TI__Mastermind 18090 points

Hello Dice,

thank you for the confirmation.

Let’s wait for the Zoom in waveform for more insight.

Regards,

Moheddin

+1 Moheddin Pasha Shaik over 1 year ago in reply to Moheddin Pasha Shaik

TI__Mastermind 18090 points

Hello Dice,

This looks like a oscillation due to large output caps and inductor, since the current is low(80mA) that is flowing through the body diode of HS-FET, I don't see a problem here.

Thank you & regards,

Moheddin.

0 Moheddin Pasha Shaik over 1 year ago in reply to Moheddin Pasha Shaik

TI__Mastermind 18090 points

Hello Dice,

If you don't have any further questions can you please close the thread by clicking on resolved.

Thank you & regards,

Moheddin.