TPS2660: LED connected with FLT pin turn on a moment during power on/off

Ryo Akashi

Genius 9470 points

Part Number: TPS2660

Hello experts,

I got question from customer.

My customer plan to use TPS26601 for their system.

They plan to indicate error with LED connected with FLT pin, when TPS26601 detect error (Over current, over VPORR).

But, LED turn on a moment during power on/off timing. They don’t want to turn on LED during power on/off timing.

TPS26601 may detect inrush current during power on timing. Or, this IC may detect V(PORR) error during power off timing.

Do you have any idea to avoid this phenomenon which LED turn a moment on during power on/off?

LED cirsuit is as below;

FLT pin -> resistor (15kohm) -> chip LED

IN pin is connected with UVLO pin directly.

OVP pin and RTN pin are connected directly, also ILIM pin is connected through RLIM with this line.

Thanks and best regards,

Ryo Akashi

over 5 years ago

0 Lokesh Ghulyani over 5 years ago

TI__Expert 8630 points

Hello Akashi-San,

Is the LED pulled up-to VIN supply ? (Similar to schematic for the EVM : TPS26600-02EVM: Evaluation Module for TPS2660x User's Guide (Rev. A).)

0 Ryo Akashi over 5 years ago in reply to Lokesh Ghulyani

TI__Genius 9470 points

Hello Lokesh-san,

Thank you for your reply.

Yes, the LED pulled up-to VIN supply. I confirmed with customer.

Also, they said that they evaluated with this TPS26002-02EVM and confirmed the LED turn on a moment during power on/off timing.

I would appreciate if you would give me some comment for this phenomenon.

Thanks and best regards,

Ryo Akashi

0 Lokesh Ghulyani over 5 years ago in reply to Ryo Akashi

TI__Expert 8630 points

Hello Akashi-San,

FLT signal also works as PGOOD output. During power-up, it is only made high after output voltage has reached input voltage

And during the power-down, it is reset when input voltage goes below V_PORF

This is described in Section 9.3.5.3 in the datasheet.

0 Ryo Akashi over 5 years ago in reply to Lokesh Ghulyani

TI__Genius 9470 points

Hello Lokesh-san,

Thank you for your reply.

I understand FLT signal works as PGOOD.

It means we can't avoid LED tuning on a moment during power-up(down). Is it correct?

Thanks and best regards,

Ryo Akashi

0 Lokesh Ghulyani over 5 years ago in reply to Ryo Akashi

TI__Expert 8630 points

Yes.

0 Ryo Akashi over 5 years ago in reply to Lokesh Ghulyani

TI__Genius 9470 points

Hello Lokesh-san,

By adding external component, can we avoid it? (for example, combine logic IC?)

My customer really want to avoid LED turning on.

Could you give me idea, if you have?

I would appreciate if you would give me comment.

Thanks and best regards,

Ryo Akashi

0 Lokesh Ghulyani over 5 years ago in reply to Ryo Akashi

TI__Expert 8630 points

Hello Akashi-San,

I have replied over email for this query.

0 Ryo Akashi over 5 years ago in reply to Lokesh Ghulyani

TI__Genius 9470 points

Hello Lokesh-san,

Thank you for your posting.

Your support is very helpful.

Thanks and best regards,

Ryo Akashi

Power management

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TPS2660: LED connected with FLT pin turn on a moment during power on/off