TPS63000: Feedforward capacitor value computation

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Part Number: TPS63000

Data sheet (Section 8.2.2.1, page 11) has Equation 2 for computing the value of feedforward capacitor. If R1 is 1Megohm, then Cff=2.2uF. This seems like a very large number. Can you please confirm that there is not a factor of 1,000 or 10,000,000 missing? I am interested in this because we have a large step on output load relatively fast.

Thanks.

over 5 years ago

0 Milos over 5 years ago

TI__Expert 7925 points

Hi Avatar,

The equation is correct, you have to use the base units when calculating Cff capacitance:

Cff [F] = 2 µs / R1 [Ohm]

Therefore for R1 = 1 MΩ you have Cff = 2 pF.

Please note that this is an approximation that usually works fine. For more details and for the correct procedure to improve the transient response, refer to this application note:
http://www.ti.com/lit/an/slva289b/slva289b.pdf

Best regards,
Milos

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TPS63000: Feedforward capacitor value computation