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UCD9090 System-Reset

Arondimal Savarimuthu
Prodigy 200 points
Other Parts Discussed in Thread: UCD9090

Hi Experts,

We are using UCD9090 in our design to manage reset and power sequence. The power sequencing is all fine with our protos. I am facing few queries with the ‘reset’ portion.

1. Is it possible to toggle the ‘System Reset’ using state change of GPI???
    That is, I will change the value of a GPIO in the UCD9090 register through PMBus.
     The reset should be toggled  (assert and de-assert) and not follow the GPIO.

2. Can the RESET PERIOD of the Watch Dog be varied during run-time through PMBus?? Say, the Reset-Period 
    is normally 15seconds. Now, I want to reset the system, so I change the Reset-Period to 1second so that the
    UCD9090 resets the system because of the WDT.

Awaiting your reply.

Regards

  • 0
    TI__Expert 5470 points

    1. Yes, it is possible to toggle the "System Reset" pin using the state change of GPI. However, you need to select both "De-assert when PG and GPIs asserted" and "Assert when Not GP an d GPIs de-asserted", and select only the GPI pins that you want the "System Reset" pin state  to depend on

    2. Changes in System Watchdog need a Store to Flash, followed by a soft reset (or hard reset) in order to function properly. If you want to reset the system by WDT, then either stop toggle the WDI pin, or stop sending the SYSTEM_WATCHDOG_RESET command (0xD4)

  • 0 in reply to Anne Ngo77
    Prodigy 200 points

    Thanks Anne for the response.

    I have tried your first answer by checking both options.

    The point is, the 'System-Reset' doe not toggle, it simply follows the state. If I pull the GPI LOW from HIGH, the System-Reset pin stays at LOW until the GPI is pulled up HIGH again.

  • 0 in reply to Arondimal Savarimuthu
    TI__Expert 5470 points

    Try to set Pulse Time to non-zero to toggle the System Reset pin