TPS2640: About overcurrent behvier

Jimmy WANG

Genius 4235 points

Part Number: TPS2640

Tool/software:

Hi team,

My customer found some issues here. I can not explain it. Could you provide your suggestion?

The schematic and waveform as below.

Test condition.

The original current limit setting is 0.8A. It's a Fan power as input application.

Next step: The customer blocked the fan on purpose then the input current will increase.

From the datasheet if Io>ICB then the timer will count 4ms.

It seems that the overcurrent does not exceed 4ms. Why does the voltage drop?

CH1 = Vo

CH3= Fan speed (Frequency Generator)

CH4= Input current

over 1 year ago

0 Jimmy WANG over 1 year ago

Genius 4235 points

Hi team,

Could you reply it? thanks

0 Amrit Jit over 1 year ago in reply to Jimmy WANG

TI__Mastermind 36281 points

Hello Jimmy,

I can't read the waveform clearly attached.

What's the input current per division value.

When Vout drops, does it turn off the FAN. because I can't see FAN speed after last one.

Thanks

Amrit

0 Jimmy WANG over 1 year ago in reply to Amrit Jit

Genius 4235 points

Hi Amrit,

Input current is 500mA per division. Due to Vo drop so some external circuit detect then shut down the fan.

So customer's question is seems no over current event occur why Vo drop? Thanks

Another question is If the peak current reaches the set value, the Timer starts counting for 4ms.
If it exceeds 4ms, turn off the MOSFET

0 Amrit Jit over 1 year ago in reply to Jimmy WANG

TI__Mastermind 36281 points

Hello Jimmy,

Jimmy WANG said:
Another question is If the peak current reaches the set value, the Timer starts counting for 4ms.
If it exceeds 4ms, turn off the MOSFET

Yes, Correct. That's the circuit breaker action.

Is there any other fault which could be registering? Can you prove VIN and FLT pin as well.

Thanks

Amrit

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TPS2640: About overcurrent behvier