TPS25940-Q1: TPS25940L-Q1 latch-off Condition

Hi Hiirakawa-san,

Yes, OVP and UVLO won't latch off the device.

Overcurrent will latch off the device. During this, device will limit the current and due to higher power dissipation of (Vin - ILIM*R_load)*ILIM, Thermal shutdown can happen which will latch off the device. 

I don't fully understand your question here (below). 

nozomu Hirakawa said:

Set OVP to 4.62V.

TPS25940L-Q1 error occyrs when VIN is 4.7V. 

If we lower the VIN from here, it will return to 4.2V.

What I would expect is for it to latch off.

Best Regards,
Arush

Hi Arush.

Thank you for answer.

I understand that OVP and UVLO won't latch off.

>I don't fully understand your question here (below). 

That is my OVP test condition.

Your answer solved the issue regarding OVP.

Another question, is it correct that it will not latch off if the limit current is lower than 2A?

Test condition is below.

--Test1

VIN：4V

ILIM：1A（R_ILIM 82kΩ)

Load：1.1A

Result.

VOUT：100～200mV and not latch off.

Reducing the load from 1.1A to 1A restores VOUT.

--Test2

VIN：4V

ILIM：2.2A（R_ILIM 39kΩ)

Load：2.2A

Result.

VOUT：0mV and latch off. However, it takes 3 seconds for VOUT to be completely turned off.

VOUT does not recover even if the load is reduced from 2.2A to 1A.

Best Regards.

Hirakawa.

Hi Hirakawa-san,

Overcurrent itself won't latch off the device. 

Arush Gupta said:

Overcurrent will latch off the device. During this, device will limit the current and due to higher power dissipation of (Vin - ILIM*R_load)*ILIM, Thermal shutdown can happen which will latch off the device. 

I should have been more clear about this. Overcurrent event won't latch off the device directly but indirectly by causing TSD event. 

This happens when overcurrent and TSD happens. Here in your test, 

nozomu Hirakawa said:

--Test1

VIN：4V

ILIM：1A（R_ILIM 82kΩ)

Load：1.1A

Result.

VOUT：100～200mV and not latch off.

Reducing the load from 1.1A to 1A restores VOUT.

Here, overcurrent event happened but TSD did not, and device recovered back.

nozomu Hirakawa said:

--Test2

VIN：4V

ILIM：2.2A（R_ILIM 39kΩ)

Load：2.2A

Result.

VOUT：0mV and latch off. However, it takes 3 seconds for VOUT to be completely turned off.

VOUT does not recover even if the load is reduced from 2.2A to 1A.

Best Regards.

Here after overcurrent event, TSD also happened and hence the device got latched off. It took 3s for TSD here. 

I hope this answers your query. Please click resolved if this answers your query. Please reply here if there are any follow up questions.

Best Regards,
Arush