TPS54160: Enable pin dips below 1.25V in the Startup

Dinu Paulson24

Part Number: TPS54160

we are using TPS54160 DC/DC Converter From Texas Instruments and we have an observation, please see the details below.

During power start we have observed dip on EN (pin 3), specifically when the VOUT(3.3V) comes up. The voltage dip is observed till 1.23V.

According to datasheet when the voltage at the VIN pin is below the VIN UVLO, EN pin pulled below 1.25 V a shutdown event occurs. But we haven’t seen any dip on 28V input line.

We want to know: 1. What is the reason for dip..?

2. the dip on EN line will impact operation of DC/DC converter, as it dips below 1.25V.?

over 4 years ago

0 Andy Chen over 4 years ago

TI__Mastermind 34875 points

Hi Dinus,

Did you test input 28V voltage on P213 node?

EN pin voltage on P209 node should be proportional to P213.

B R

Andy

0 Dinu Paulson24 over 4 years ago in reply to Andy Chen

Expert 1320 points

Hello Andy,

We have not checked on P213, we were testing it on Main 28V input.

I have repeated the test and checked on P213 and we could see a dip.

Is it due to the inrush required by the output side..? What I shall do to mitigate this, increase in input bulk capacitance ...?

Regards,

Dinu.

0 Andy Chen over 4 years ago in reply to Dinu Paulson24

TI__Mastermind 34875 points

Hi Dinu

Pls try below suggestion:

1. use L14 with lower DCR

2. C178 and C173 should be 50V or higher rating,

3. replace C173 with 22uF 50V electrolytic cap.

B R

Andy

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TPS54160: Enable pin dips below 1.25V in the Startup