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UCD9090: How to shut down rails when external temp sensor triggers temp fault?

Asko Oinonen
Prodigy 110 points
Other Parts Discussed in Thread: UCD74111, UCD9222, UCD9090

Hi,

I'm using combination UCD9090, UCD9222 &  two UCD74111 to power two DSPs. I have external temp sensors glued to DSP heat sinks to monitor DSP temperatures. I want to turn all power rails off, when temp fault occurs.

I connected TEMP_FAULT signal (active low) to UCD9090 GPI1 (pin 4). I configured the GPIO1 pin as "GPI Fault Enable".

I can read the state of the pin correctly with GPIO pins peek/poke command. Also when I enabled fault log for GPI1 pin the fault was logged.

I thought selecting GPI1 on "GPI Seq Off Dependencies" (see picture) might work but it doesn't.

Any idea how I can turn the rails off with this GPI1 input?

Regards,

Asko

  • 0
    TI__Genius 9845 points

    The sequence-off dependency cannot initiate a shut down sequence. The dependency is only examined after a sequence is initialized.

    GPI input cannot trigger a fault shutdown. 

    You have two options:

    (1) connect analog temp signal to a MON pin, and use it as a temp monitor. 

    (2) connect digital OT signal to a MON pin, and use it as a temp monitor.  

    In fault response, you can configure OT fault response to be shutdown.

    Regards,

    Zhiyuan

  • 0 in reply to Zhiyuan Hu
    Prodigy 110 points

    Hi Zhiyuan,

    Thank you for your advice.

    I connected digital over temp signal to MON10 input, adjusted under voltage limit to 300mV, set MON10 under voltage fault response to "shut down immediately" and set tab on fault shutdown slaves on all other rails. Now all DSP power supplies turn off when over temp situation arises. Very good.

    Operation is now almost what I want, but one improvement I'd like to have. When over temp situation stops (there's 10 degree C hysteresis in temperature manager), I'd like to have all power rails to switch on automatically. Do you think it's possible?

    Regards,

    Asko

  • 0 in reply to Asko Oinonen
    TI__Genius 9845 points
    Once rails are sequenced off due to a fault, it requires toggling a "master switch" to initiate a turn-on sequence. This "master switch" can be CONTROL pin or OPERATION command or toggling Pin-Selected States using a GPI.

    For example, if you use CONTROL pin to initiate a sequence, all rails' ON_OFF_CONFIG should be configured to CONTROL Pin Only. Then you need to assert CONTROL to initiate a turn-on sequence. After a fault shutdown, you need to toggle CONTROL pin to turn the rails back on.

    You may consider to connect the temp sensor logic output to CONTROL pin. OT will de-assert CONTROL pin to turn off the rails, and once OT condition is removed, it automatically asserts the CONTROL pin.