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TPS65217: Reboot / Reset device via I2C

QumJo
Intellectual 280 points
Part Number: TPS65217

Hi folks

I would like to programmatically issue a reset of the TPS65217 via I2C.


I found I could set a timer to e.g. 1 sec to issue a SEQUP and then set the SEQDWN bit and it should torn off the outputs and turn on again. Would that be possible? Unfortunately I do not have access to nRESET or PB_IN etc.

Any hint or trick you can suggest'

  • 0
    TI__Mastermind 19976 points

    Hello,

    Thank You for using E2E! If only I2C is available for a power cycle, then bit "SEQDWN" in the SEQ6 register can be used to trigger a power-down sequence while the device is in active state and "SEQUP" bit in the same register can be used to power them up again. Please note that executing a power-down sequence with "SEQDWN" wont be equivalent to sending the device to the RESET state. When using SEQUP and SEQDWN, only the rails controlled by the sequencer are shutdown.

    Thanks,

    Brenda

  • 0 in reply to Brenda Diaz
    Intellectual 280 points

    Hi Brenda

    Thanks for your reply. I already tried setting the SEQDWN bit and it works, thing is that the device writing the bit is powered by the output of the PMIC and once SEQDWN is written my device is OFF forever. That is, the I2C master will loose its power supply and can not write the SEQUP bit anymore. As said, I try to fabricate a software initiated hardware reset. So I tried setting both SEQUP and SEQDWN bit (0x03) to regsiter 0x1e in the hopes that SEQUP is triggered right after SEQDWN but this does not seem to be the case. Any idea on how I could achieve what I need? (we can be very creative here - e.g. moving to USB power where there is no input, and hence PMIC would switch back to AC input but in the short period of switching between modes has outputs off or something...)

    Thanks!

  • 0 in reply to QumJo
    TI__Mastermind 19976 points

    Hello,

    If there is no access to the nRESET, PB_IN and PWR_EN pins and the I2C communication is not an option to turn the rails back ON, then the only option I can think off would be to disconnect the main supply after the power-down sequence is complete (SEQDWN=1b) and connect it back again to transfer the PMIC from OFF state to ACTIVE. 

    Just for reference, I also wanted to share the links to the schematic checklist and the brownout application report which are two critical technical documentation to help our customers with the TPS65217 designs.  

    TPS65217x Schematic Checklist (Rev. C)

    Designing Robust TPS65217 Systems for VIN Brownout

    Thanks,

    Brenda