TPS2553: Handling Inrush current

Saravana Kumar

Part Number: TPS2553

Hi,

We are using TPS2553 load switch at 3.3V supply rail which is supplying a LCD panel.

The LCD panel current consumption is around 500 mA during normal operation. And during start-up, the inrush current may go up to 1.5 A for a maximum duration of 470us.

We came to know about inrush current specifications after boards arrived. According to our design configuration, the load switch will work for normal operation i.e. 500 mA load current.

But the load switch is tripping/entering in to fault condition during inrush time.

We are looking for a solution to handle inrush without changing the load switch part for current version of the board. Please suggest.

Regards,

Saravana

over 3 years ago

0 Bob Ma over 3 years ago

TI__Expert 8980 points

Hi, Saravana,

Thanks for reaching out. Sorry we are in public holiday so not able to reply your question now. We will back to office on May 5th and reply your question then.

Bob

0 Ziv Zhang over 3 years ago

TI__Mastermind 18031 points

Hi Saravana,

I don't think it trigger the fault condition, because the fault time deglitch is 8ms. Maybe it's shut down as with heavy load as turning on. Try to decrease the output cap or increase current limit threshold.

If you have any other concern, contact me any time.

If you think resolved, please help click 'Issue is solved button'.

Thanks.

0 Saravana Kumar over 3 years ago in reply to Ziv Zhang

Prodigy 50 points

Hi Ziv,

Yes, the fault signal is not getting triggered but output voltage is dropping down to 2V. Please refer below image which we capture for load switch with 500mA limit. With this setting the display is not working.

Green - Output voltage, Yellow - Input voltage, Orange - Fault output

When we changed the current limit for load switch to 1.5A, the output stability time is around 15s. Please refer below image. With this setting the display is working fine.

Please check.

Regards,

Saravana

0 Saravana Kumar over 3 years ago in reply to Saravana Kumar

Prodigy 50 points

Please ignore about the second waveform. The 15s delay is introduced by software for enabling the load switch. I will share correct waveform in short time.

0 Ziv Zhang over 3 years ago in reply to Saravana Kumar

TI__Mastermind 18031 points

Hi Saravana,

The first waveform should be normal current limit instead of inrush. It should be current limited normally and assert fault. Please check your set-up and check whether meets the requirements of 8ms deglitch time?

0 Ziv Zhang over 3 years ago in reply to Saravana Kumar

TI__Mastermind 18031 points

HI Saravana,

If you can't find the root cause, please with tps2553 on only and remove other device or use one EVM to double check.

0 Saravana Kumar over 3 years ago in reply to Ziv Zhang

Prodigy 50 points

Hi Ziv,

Yes, we will check. As of now we can close the issue.

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TPS2553: Handling Inrush current