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UCD90160 GPI control question

Hoang Manh
Intellectual 380 points
Other Parts Discussed in Thread: UCD90160

Hi all,

We are designing a PCI express card, and using a UCD90160 for voltage monitor and sequencer. 

The POWER-ON sequence is not a problem, I can monitor the input 12V for control this.

The question is for POWER-OFF: Can I only use only a GPI pin for POWER-OFF condition? Example, when the GPI pin is zero, the POWER-OFF sequence starts.

Please give me any advice.

Thanks and Best Regards,8688.UCD90160_PowerMonitor.pdf

Hoang,

P/S Attached is also the schematic for your reference.

  • 0
    TI__Genius 9845 points

    Yes. You can use pin selected states.

    Thanks,

    Zhiyuan

  • 0 in reply to Zhiyuan Hu
    Intellectual 380 points
    Hi Zhiyuan,

    Sorry but there is one more thing I need to know to control our power sequence.
    How long does it take until the UCD90160 can operate normally after power on (including the configurate time)?

    Thanks and Best Regards,
    Hoang
  • 0 in reply to Hoang Manh
    TI__Genius 9845 points

    Hi Manh,

    Normally the initialization is about 20ms. But if log is corrupted (which may happen when power is dropped before the device finish writing fault logs into flash), the device needs time to clear the log before starts normal operation. In that case, depending on how many logs need to be cleared, the worst case can take additional 160ms.

    If you can enable the brown-out feature in the device, and implement the brown-out circuit as described in datasheet, it will prevent log corruption from happening. If you don't have a standby 3.3V that will stay alive when main power is dropped (in such an event, all rails may report fault, sequencer will be busy writing the faults), we highly recommend the brownout circuit to prevent log corruption.

    Thanks,

    Zhiyuan

  • 0 in reply to Zhiyuan Hu
    Intellectual 380 points
    Hi Zhiyuan,

    Thanks for the information.
    We also use a GPIO as a reset signal for system. One of our chips requires the rise time for reset signal must not exceed 200 ns. I search the rise time for those GPIOs in UCD90160 datasheet , but not found out this information.

    Can you help clarify ?

    Thanks and Best Regards,
    Hoang
  • 0 in reply to Hoang Manh
    TI__Genius 9845 points
    Hi Hoang,

    I don't have this information.

    The rise time depends on the series resistance of the GPIO pin and the load capacitance (your chip's reset pin). From the datasheet VOL=0.25V @ 6mA, we can derive the series resistance is about 42ohm. You can calculate the RC constant using the reset pin's capacitance (usually a few pF). I believe the rise time is much shorter than 200ns.


    Thanks,
    Zhiyuan