TPS55330: about Soft-Start

T Kishi

Part Number: TPS55330

My Customer has question.

In the explanation of Soft Start, it is stated that clamping the output of the error amplifier till the SS terminal becomes 1.8 V.
Which period is this referring to?
① Period during which the output voltage starts to rise after EN rises
② Is the period during which the output voltage starts to rise?

Best Regard

T Kishi

over 6 years ago

0 Helen chen over 6 years ago

TI__Mastermind 40080 points

Dear Sir,

It means both periods: 1+2 .

0 T Kishi over 6 years ago in reply to Helen chen

Genius 4425 points

Hi Helen

Thank you for reply.

I think that it is possible to obtain the approximate value of the rise time with the TYP 6 uA constant current source and the external capacitance, 1.8 V as the SS terminal voltage.
However, at the rise time of SS and the rise of output voltage
There is a big difference.
Why does this happen?

Regard
T Kishi

0 Helen chen over 6 years ago in reply to T Kishi

TI__Mastermind 40080 points

Hi Sir,

The rise time of SS doesn't has linear relationship with the rise time of output voltage. 1.8V terminal voltage just means the time when the IC could reach maximum duty.

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TPS55330: about Soft-Start