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TPS65217DEVM: TPS65217D - How to prevent default power up sequence

dhanasekaran k
Prodigy 90 points
Part Number: TPS65217DEVM
Other Parts Discussed in Thread: TPS65217

we use TPS65217D(PMIC) to power up AM335x; From the PMIC datasheet when AC(power) given to PMIC, it generates wakeup and gets PWR_EN within 5s then enables dcdc and LDO

(Default power up sequence ).

This default sequence not suited to our board, so how to stop this default power up sequence.

Thanks in Advance,

dhanasekaran k

  • 0
    TI__Expert 8730 points
    Hi,

    I have assigned your request to responsible Applications Engineer and we will get back to you as soon as possible.

    Regards,

    Murthy
  • 0
    TI__Mastermind 30260 points
    Why does this power-up sequence not work in your design? The TPS65217 is designed as the ideal PMIC for the AM335x processor. The power-up sequence should be in the correct order by default.

    If you stop the power-up sequence, how will the AM335x receive power to enable the rest of the system? Only SYS and the LDO1 output will have power when PWR_EN is low.

    If this is okay, you can try Enabling the additional power rails manually by writing I2C to Reg. 0x0C and setting PWR_EN high after the manual power-up sequence is complete. If all of the I2C commands are done withing 5s and PWR_EN transitions to high, the automatic power-down sequence will not occur.
  • 0 in reply to Brian Berner
    Prodigy 90 points

    Thanks for your reply.

    Please Correct me if am I wrong. when I provide power to TPS65217 it's automatically wake-up AM335x processor then processor sets PWR_EN automatically to high within 5s. If I can't or do I2C write within this time the default(supply) sequence will happens right. Is this default power sequence affects processor?

    and is there any possibility manually wake-up and PWR_EN transitions to high (i.e) I want to wake-up manually after my I2C write then PMIC get enable with in 5s.

    Regards,

    dhanasekaran k

     

  • 0 in reply to dhanasekaran k
    TI__Mastermind 30260 points
    Yes, the nWAKEUP (from TPS65217) and PMIC_PWR_EN (from AM335x) signals normally happen automatically.

    But PMIC_PWR_EN only goes high because the PMIC driver built into the firmware tells it to go high ASAP. In order to change this automatic behavior, your would need to modify the PMIC driver in the Linux kernel provided by TI.

    Since the TPS65217 default behavior cannot be changed in code, modifying the firmware code for the AM335x would be easier. Unfortunately, I am not an expert on the AM335x Linux kernel and drivers, so this question would need to be asked on the AM335x separately.
  • 0 in reply to Brian Berner
    Prodigy 90 points

    Thanks a lot for your reply.

    Can you tell me the default voltage driven by DCDC converters and LDOs in  TPS65217D.

    is it depends on Reset Value of PMIC registers. Especially I want to know LDO3 drives 1.8v or 2.45v(from reset value in it's Register).

    one more thing i want to get know is that LDO and DCDC enable bits are disabled when see RESET VALUE of Enable Register But how they drives voltage during Default power sequence(Discussed above).

    Regards,

    Dhanasekaran k

  • 0 in reply to dhanasekaran k
    TI__Mastermind 30260 points
    This follow-up question was also asked and replied to in a new thread: e2e.ti.com/.../2307739