LM60430-Q1: Input voltage decline slowly

Allen yang

Part Number: LM60430-Q1

Hi Team

What is the problem with the following conditions?

Input 24V, output 12V/3A

Input voltage drops slowly to 9V

Whether the output voltage can be maintained above 8.6V

0 Colin Chen over 1 year ago

Hi Allen,

I have calculated and think that it can be maintained above 8.6V. As you can see that Fsw will drop to 140kHz in dropout mode.

SoToff=(1-D)⋅T=(1-8.6V/9V)⋅(1/f)=317ns, and it is higher than T-off_min =70ns. We can get that it can be guaranteed.

Thanks

Colin

0 Allen yang over 1 year ago in reply to Colin Chen

But FB Pin is set to 12V out

Will the input voltage drop to 9V have any Issue?

+1 Colin Chen over 1 year ago in reply to Allen yang

Hi Allen,

It is ok when Vin < Vout, this condition we call dropout mode and output voltage will fall with the input voltage until device shut down.

Thanks

Colin

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