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Original question:

TPS22990: Is there a maximum CT(pF)/output rise time spec?

TPS22990: TPS22990: Is there a maximum CT(pF)/output rise time spec?

Dean McKnight
Prodigy 30 points
Part Number: TPS22990

TPS22990: Is there a maximum CT(pF)/output rise time spec?

I have followed the old threads but my question is not answered.

I am using TPS22990 as a Voltage Switch.

VIN = 5 V

VBIAS = 5V

ON = 5V 

All 5V are applied at the same time. Is this acceptable ? or do I need to sequence these ? VIN, VBIAS and then assert ON ?

I see a Vout T Rise of 1 ms under these conditions:

Ct = 0.47 uF

Cin = 1.0 uF

Cout at device = 0.1 uf

Cload is ~ 200 uF

I am expecting a T Rise on the VOUT of ~ 15 ms, but see 1 ms T rise

I added more Ct and still 1 ms.

Can this switch give me a T rise of 15 ms ? under these Voltage and load conditions ?

Thanks !!!

  • 0
    TI__Genius 10855 points
    Hi Dean,

    Thanks for reaching out on E2E!

    You are correct regarding the sequencing. Can you try applying voltage on VIN and VBIAS first, and then asserting the ON pin afterwards?

    Looking at the system conditions, I don't see anything else incorrect. Please note that with a large Cload, if the input supply were to suddenly dip to 0V there could be a large amount of reverse current going from VOUT -> VIN. Do you see this condition happening in your system?

    Thanks,
    Arthur Huang