TPS54331: TPS54331DR UVLO Setting Problem

Cheney_Sun

Part Number: TPS54331

Hi TI EE：

When I use TPS54331DR as 5V Vin to 1.2V Vout buck IC,I want to use another power rail 3.3V to control the UVLO point.

When the 3.3V power rail raise up to 2.8V ,the TPS54331DR will start to work and when the 3.3V Power rail fall down below 2V,the TPS54331DR will shut down.

Please help to make sure if that setting is reasonable.

Thank you very much.

Best Regards

Cheney_Sun

over 6 years ago

0 Jason Wang (BSR-MV) over 6 years ago

TI__Genius 9550 points

Hi,
please tell me the resistors value which connect with EN pin.

0 Sam(MPAA) Zhang over 6 years ago

TI__Mastermind 19080 points

Hi Cheney,

Yes you can do this. Please take Chapter 8.3.4 in datasheet as reference to calculate the resistor values.

Regards,
Sam

0 Cheney_Sun over 6 years ago in reply to Jason Wang (BSR-MV)

Intellectual 595 points

Hi Jason:

REN1:267Kohm,REN2:210Kohm.Please help to make sure if that REN1,REN2 Value is reasonable.Thank you.

Regards

Cheney_Sun

0 Cheney_Sun over 6 years ago in reply to Sam(MPAA) Zhang

Intellectual 595 points

Hi Sam
REN1:267Kohm,REN2:210Kohm.Please help to make sure if that REN1,REN2 Value is reasonable.Thank you.
Regards
Cheney_Sun

0 Shawn Nie over 6 years ago in reply to Cheney_Sun

TI__Genius 10070 points

Hi,

The right value should be REN1=267Kohm, REN2=183Kohm.

Shawn

0 Cheney_Sun over 6 years ago in reply to Shawn Nie

Intellectual 595 points

Hi Shawn:

Thanks

If EN is typical value :1.25V,REN2=183Kohm.

But if EN is worst case 1.35V,RN2=210Kohm.

I think I should calculate the worst case UVLO REN1,REN2.

Cheney_Sun

0 Shawn Nie over 6 years ago in reply to Cheney_Sun

TI__Genius 10070 points

Hi Cheney,

Okay, you can use this value. But for most of devices, the Vstart and Vstop would be lower than 2.8V and 2V.
What is your application? Dose you want to ensure the device can start up when Vin increases to 2.8V?

Shawn

Power management

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TPS54331: TPS54331DR UVLO Setting Problem