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TPS659037: TPS6570379 to power AM5718

Rakesh Muralidharan
Expert 2810 points
Part Number: TPS659037
Other Parts Discussed in Thread: AM5718, TMDXIDK5718, AM5728,

Hi,

In my design I have used TPS6570379 PMIC to power AM5718

1. My requirement is to have a self turn ON scheme (ie Auto ON when power applied)

2. Have a software shutdown scheme. AM5718 should be able to call a shutdown from software resulting in PMIC executing its power down sequence.

As I understand as long as POWERHOLD is held high DEV_ON cannot trigger shutdown from software.

I tried to experiment with RPWRON signal of TMDXIDK5718. What I have observed is that if RPWRON  pulled down permanently , On applying power to PMIC it auto-Tuns ON AM5718.

On triggering shutdown via PWRON (pushbutton) PMIC shuts down AM5718 and will not re-trigger turning ON AM5718 even in RPWRON is held low.

Is this observation expected.??

If so i guess I can

1. Hold POWERHOLD  to ground

2. Hold RPWRON  to ground

3. On applying power PMIC will turn ON. Software should hold PMIC to remain ON by setting DEV_ON bit in PMIC. ( I guess AM5728 evm AM572x GP has this implementation in its uboot)

4. For turn OFF AM5718 will reset DEV_ON. and 

5. PMIC will turn OFF AM5718 and remains in turn OFF condition without triggering new turn ON cycle.

please point out if there is any flaw with this implementation.

  • 0
    TI__Prodigy 370 points
    Hi Rakesh,

    In regards to the observation you made on the PMIC not re-triggering turning ON the AM5718 even if RPWRON is held low that is the expected outcome because it is not a level sensitive pin. This pin is edge sensitive so being held low will not make it turn on.

    As for turning on the device, it does not startup automatically it needs an ON request by using PWRON or POWERHOLD. I recommend looking at Figure 4 in the user’s guide www.ti.com/.../sliu011 to implement it turning OFF via software.

    Thank you,

    Jadyn
  • 0 in reply to Jadyn
    Expert 2810 points

    Hi,

    I guess scheme in Figure 4 mentions Power ON via pushbutton at PWRON . POWERHOLD is pulled up to V1v8_processor.

    i am looking for a Autopower ON with s/w shutdown (SD) trigger.

    If I use GPIO_0 and GPIO_7(POWERHOLD) as in figure will it work.

    As i understand , on applying input power if POWERHOLD is pulled up to VRTC then auto ON is triggered for PMIC. Now to power OFF i need to apply Low to POWERHOLD.

    GPIO_0  defaults to input during power up. Table 3-1 TPS659037 datasheet. Thus POWERHOLD remains in pulled-up state.

    For shut down AM5718 can configure GPIO_0 as output and set to ""Low"". This ""Low"" will  be latched and trigger PMIC SD via POWERHOLD. After processor shutdown, POWERHOLD will remain low until the next power cycle for PMIC (HWRESET) .

    I no more need the sw DEV_ON feature.

    Will this scheme work??

    Also ""RPWRON is held low that is the expected outcome because it is not a level sensitive"" Is it not Level sensitive?? Table 5-8 TPS659037 datasheet.

  • 0 in reply to Rakesh Muralidharan
    TI__Prodigy 370 points

    Hi Rakesh,

    If it is available I recommend using GPIO5 because it defaults to the push-pull configuration which will help when you are setting it "low", where GPIO0 is open drain. Lastly RPWRON is edge sensitive and thank you for bringing Table 5-9 to our attention we will work to make this clearer in the next revision of the datasheet. As for now I recommend looking at Table 5-6 www.ti.com/.../tps659037 where it talks about RPWRON using falling edge detection. Please let me know if you have any further questions.

    Thank you,

    Jadyn