TPS82130: Soft start capacitor range

Jonathan Bender

Part Number: TPS82130

Hello,

What is the recommended range for the soft start capacitance value on TPS82130?

I have a design that uses C_SS = 390 pF, which corresponds to a 200 us soft start time. At some point, too small of a C_SS will be equivalent to C_SS = open, but I wanted to understand what the practical design range should be.

Thanks,

Jonathan

over 6 years ago

0 Chris Glaser over 6 years ago

TI__Guru*** 145700 points

Hi Jonathan,

There isn't really a recommended range for the SS cap. It is entirely dependent on the application's needs. If there are no specific needs, 'slower' is usually better than 'faster' as shown here: www.ti.com/.../slyt669.pdf

The 390 pF value may come from TINA/Webench. They generally choose the smallest possible time so that the simulations run faster.

0 Jonathan Bender over 6 years ago in reply to Chris Glaser

TI__Expert 7895 points

Thanks Chris, great app note, and you're right, 390 pF is what Webench came up with by default. Will increase C_SS to 8.2 nF to get a 4 ms soft start, barring any different startup requirements by the load.

Jonathan

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TPS82130: Soft start capacitor range