TPS7A7300: Formula for soft start delay vs. Css

Alice57

Intellectual 1730 points

Part Number: TPS7A7300

Hi LDO Support Team,

Could I get the formula about soft start delay vs. Css? Do we have calculate sheet about it?

Best regards,

Alice

over 7 years ago

0 Ryan Eslinger over 7 years ago

TI__Guru 55940 points

Hi Alice,

The softstart delay has a linear relationship to the size of Css as shown in Figure 42 in the datasheet.

Very Respectfully,

Ryan

0 Alice57 over 7 years ago in reply to Ryan Eslinger

TI__Intellectual 1730 points

Hi Ryan,

Thank you for the comment. Yes, the relationship between softstart delay and Css is linear, I think there will be an fixed formula. Do I understand correct?

Best regards,
Alice

0 Ryan Eslinger over 7 years ago in reply to Alice57

TI__Guru 55940 points

Hi Alice,

Taking points from Figure 42 I estimate that the slope of the line is ~224 us/nF. From the datasheet we know that the internal delay with no external capacitor is 700 us. This yields the equation

softstart delay (ms) = 0.224 (us/nF) x Css (nF) + 0.7 (us)

Very Respectfully,

Ryan

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TPS7A7300: Formula for soft start delay vs. Css