Cbuf value on TPS62730

Yaniv Reibenbacg

Other Parts Discussed in Thread: CC1120

Hi,

We are doing a design using CC1120 + MSP430 and the DC2DC TPS62730

Could you advise what value of a input buffer capacitor (Cbuf) I should use with the TPS62730 assuming that we only transmit for a duration of 1 millisecond every 1 second with 4dBm out put power.

Or in short - about 27mA current consumption for duration of 1 ms tx bursts...

We are using a coin cell battery(CR2032).

What should be the capacitance of the Cbuf?

Attached is the deisgn of the DC2DC block

Thank you,

Yaniv

over 9 years ago

0 Florian Feckl over 9 years ago

TI__Expert 7110 points

I would recommend to use at least 220uF polymer or tantalum capacitor. However, the bigger the better.

If you are able to use a 330uF as well, this would definitely buffer what you need.

0 Yaniv Reibenbacg over 9 years ago in reply to Florian Feckl

Intellectual 860 points

Thanks for the answer.

Can I also use ceramic capacitors? the titanium capacitors seem to have high leakage current

Regards,

Yaniv

0 Florian Feckl over 9 years ago in reply to Yaniv Reibenbacg

TI__Expert 7110 points

Please apologize the delay.
Yes you can use ceramics as well - please consider the DC bias effect of these types.

The high leakage of the polymer caps is just present at the beginning and will go down by time to very small values as well.

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Cbuf value on TPS62730