TPS62441-Q1: short circuit test

Hello Pan,

Let me look at it and reply.

Thanks,

Farheen

hello Pan,

I have few questions:

Are you removing the short in between: in highlighted area?

In general, yes, when the device is in current current limit, Vout should drop and get back to normal once there is no short circuit.

Thanks,

Farheen

Hi Farheen,

We didn't remove the short and kept the load at 0.05 ohm in CR mode.

Hi Farheen,

Could you please help check the behavior?

Thank you. 

Is the green curve output current?  If yes, the looking what customer has for output current, during the time when the current is higher than current limit of the device, output voltage should drop. 

It will go back to normal operation once the current is back to normal value (under the current limit).

Thanks,

Farheen

Hi Farheen,

The green curve is the inductor current which is measured by current probe.

Do you think the behavior is correct as expected?

Could you kindly help verify this behavior on the EVM board at your side?

We would like to know why current drop or during the load at 0.05 ohm.

Could you please help clarify it?

Thank you.

Hello Weixu,

yes I will check today also...

Thanks,

Farheen

Hi Farheen,

Do you mean that this is the expected behavior for the TPS62441-Q1?

Thank a lot for your effort.

yes.

Thanks,

Farheen

Hi Farheen,

Got it, many thanks.

Hi Farheen,

There are a few questions about the waveform.

Is the red curve output voltage?

If yes, I think there is different to our waveform.

The voltage rises as the current decreases in our measurement.

But in your waveform, the voltage drops as the current decreases.

This is confusing to me.

Could you please help clarify it?

Hello Pan,

I am testing with electronic load with 2.5A continuously from the beginning.  There are two different testing enviroment.

You can refer to below digaram for reference:

As below validation data also tells, when the device is in current limit (Green Inductor current), Vout (Cyan color ) drops down. Once it goes down, Vout is back to to normal value again.

Thanks,

Farheen

Hi Farheen,

Did you observe the same test result that VOUT and CURRENT cycle up and down, as shown in the waveform we previously provided?

Due to I don't see the same behavior in your waveform.

Could you please help check it?

I would like to confirm whether we observed the same behavior.

Thank you.

Hello,

This is tested in the lab here: You could see when the IL (which is inductor current hits the limit), Vout drops down.

But I have measured also:

You see in the beginning cycle, when inductor current is higher than current limit, Vout drops down.Then after certain cycles, device restarts and both inductor current and Vout starts to rise.

Thanks,

Farheen

Hi Farheen,

I would like to check with you again about the waveform I measured before.

Do you think this is the expected behavior for the TPS62441-Q1?

Thank you.

Hello  Pan,

Green waveform does not look like inductor current to me. Looks like it is output current. because when the Vout is regulating, inductor current supposed to look like below blue curve in FPWM mode.

So looking at green waveform, the time when output current is high, Vout is zero and it starts up again when the current is going down. So that is the right behavior.

Thanks,

Farheen