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TPS22990: Capacitance Ratio Question

David C
Expert 3350 points
Part Number: TPS22990
Other Parts Discussed in Thread: TPS2290

Looking at the TPS22990 to use as a controlled switch for 3.3VDC and 5VDC.  I noticed in the datasheet that it recommends an input to output capacitance ratio of 10 to 1.  So if there was 100uF of capacitance on the output, I would need 1mF of input capacitance.  Is there anything specific reason for such a large input to output capacitance ratio?  As long as the input voltage stays above the recommended minimum operating voltage during the inrush current and I have less than the 10 to 1 input to output capacitance ratio, are there any issues with the TPS2290 operating correctly?

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    TI__Prodigy 240 points

    Hi David,

    Thank you for your questions about TPS22990!

    The recommended 10:1 capacitor ratio helps minimize the voltage dip on VIN due to transient inrush current when the device is turned on. However, a lower ratio (such as 1:1) can be used. A 1:1 ratio may cause a slight dip on VIN upon turnon due to inrush current. If there is significant inrush current using a 1:1 ratio, it is recommended to increase capacitance on the CT pin for a longer rise time.

    Please let me know if you have any more questions regarding the TPS22990.

    Best regards,

    Rachel Richardson

    If my reply answered your question, please click the "This resolved my issue" button. This can help others verify that a solution was found!