TPS53319: OVP ration and FB ratio

Naizeng Wang

Part Number: TPS53319

Tool/software:

Hi team,

BU suggests to set the ratio of OVP to be same as FB ratio. If they are not equal, the circuit may not start up. Could you please explain the reason? I cannot really understand the internal circuit. What does the +20% mean?

9 days ago

0 Savith Kumar Rayakanti 9 days ago

TI__Expert 5740 points

Hi Wang

OVP is set to be 120%*Vref, you can set the feedback resistor divider to any desired output voltage within in the spec of datasheet.

Ovp triggers when the Vout is 120% of desired Vout.

Thank you

Savith

0 Naizeng Wang 9 days ago in reply to Savith Kumar Rayakanti

TI__Expert 5380 points

Hi Savith,

As I know, during soft start, Vref will increase from 0V to 0.6V, so OVP threshold will increase from 0V to 0.72V. If OVP ratio is larger than FB ratio, for example, vout is set to 5V, so FB ratio is 0.12, if OVP ratio is 0.2. so during soft start, the voltage on OVP pin is 0.2*Vref, the OVP threshold is 0.12*Vref, so OVP is triggered, correct?

0 Savith Kumar Rayakanti 2 days ago in reply to Naizeng Wang

TI__Expert 5740 points

Hi Wang

generally OVP is only activates after boot up, and ovp =1.2*Vref

Thank you

Savith

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TPS53319: OVP ration and FB ratio