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TPS27081A: Is there a waveform of turn on

Toshihiro Watanabe
Genius 10235 points
Part Number: TPS27081A
Other Parts Discussed in Thread: TPS22975, TPS22918, TPS22971,

Hello,

We would like to see the waveform of turn-on. The condition is Vin = 0.9V or 3.3V. The rise time is approximately 10~50us.

It would be helpful to share the waveform if the similar condition is existing.

We tried to 50us turn on by LDO soft start function. We expected Vout is risen linearly from 0V to Vout but there was a below link.

e2e.ti.com/.../739929

We would like to correct this. We would like to know if TPS27081 rise waveform is linear or smoothly risen.

Best regards,

Toshihiro Watanabe

  • 0
    TI__Genius 10855 points

    Hi Watanabe-san, 

    Thanks for reaching out on E2E!

    Can you share more details regarding the application, what are your input / output capacitance, CSS capacitors, load current?

    I also recommend switching to a newer load switch if possible. I recommend looking at the TPS22918 or the TPS22975.

    Thanks,

    Arthur Huang

    To find the latest information on Power Switches, visit www.ti.com/powerswitch

    Please click "This resolved my issue" button if this post answers your question.

  • 0 in reply to Alpha H
    TI__Genius 10235 points

    Hello Arthur-san,

    I am sorry for my late reply. Is TPS22918 or TPS22975 able to set ramp up time with in tens us? If yes, I will check the condition of yours.

    Best regards,

    Toshihiro Watanabe

  • 0 in reply to Toshihiro Watanabe
    TI__Genius 10855 points

    Hi Watanabe-san,

    Unfortunately, these devices won't be able to ramp up in ~tens us. The closest equivalent we have is the TPS22971.

    Regarding the TPS27081A, because it is only a PMOS + NMOS, it will be susceptible to the output coming up when the input is applied. The reason is because the capacitor that controls the timing also slows down the charge and discharge of the PMOS gate. Therefore, when the input is applied, it takes time for the PMOS gate to be pulled high (OFF), and during this time, the PMOS allows current to flow from IN to OUT.

    For more information on the specifics of this event, you can take a look at section 4.2 in this application note.

    Thanks,

    Arthur Huang

  • 0 in reply to Alpha H
    TI__Genius 10235 points
    Hello Arthur-san,
    We are interesting in TPS22971. Please let me ask in new post which device name TPS22971.
    Best regards,
    Toshihiro Watanabe