TPS26600 Design Calculator vs Datasheet?

Peter Adams

There seems to be an error in the TPS26600 Desing Calculator or in Equation 2 (pg 20) in the datasheet. If you use the default values in the spreadsheet it recommends 0.220uF, but if you use the equation in the datasheet it would give you 27.5nF (approximated to 22nF).

Which is the correct value?

over 8 years ago

0 Venkata Nandam over 8 years ago

TI__Intellectual 2800 points

Hi Peter,

Design calculator is optimised for 220uF output capacitance, 1A load current and the corresponding Cdvdt cap is 0.22uF .

Equation 2 in datasheet considers Cout = 47uF, 2A load current and the required Cdvdt is 22nF. If you enter 47uF output capacitance and 1A load condition, design calculator recommends 22nF.

Regards,
Venkat

0 Peter Adams over 8 years ago in reply to Venkata Nandam

Prodigy 200 points

Thanks for the reply.

The output capacitance is not used in the dv/dT startup time calculations in the spreadsheet (cell D42) and is not used in the formulas in the datasheet. (it is used in the dv/dT charge current calculations (cell D43).)

According to the datasheet, the output voltage is matched to the voltage at the dv/dT pin times the gain factor (24.6). The output capacitance does not enter into it.

I'm assuming the datasheet is correct?

0 Peter Adams over 8 years ago in reply to Peter Adams

Prodigy 200 points

Got it, sorry for the confusion.
Thanks.

0 Venkata Nandam over 8 years ago in reply to Peter Adams

TI__Intellectual 2800 points

Hi Peter,

Cell D42 equation matches with the datasheet. Where as Cell D43 is calculated based on required charging current. Let me know if you have any questions on the design calculator.

Regards,
Venkat

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TPS26600 Design Calculator vs Datasheet?