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Original question:

AM4372: TPS65218D0 connection

TPS65218D0: AM4372 RTC disabled connection

Kanae
Guru 10105 points
Part Number: TPS65218D0
Other Parts Discussed in Thread: AM4372,

Hi Power management Support Team,

I have a question about PMIC regarding the following post.

e2e.ti.com/.../3608970

Regarding the connection between AM4372 and TPS65218D0 with the RTC function disabled,
the current customer's schematic is as follows

"Current schematic around the PMIC".

Q1. Is there any problem to modify this schematic as follows.
       This setting are referred to the AM437x schematic checklist; Table 2-3 RTC.

       www.ti.com/.../sprace0a.pdf  

    -RTC_KALDO_Enn: Any AM437x 1.8 V power supply -> VDDS_RTC
　-PMIC_POWER_EN : RTC_PMIC_EN -> NC

Q2. do I need an inductor or some other circuit for the output?
　Or can I use a 10kΩ pulldown as I do now?

Q3. What should I pay attention to in connecting AM4372 and TPS65218D0 when I disable the RTC function in other cases?

Q4. As the following thread, the combination of AM4372 and TPS65218D0
　should be required the connection in "Powering the AM335x, AM437x, and AM438x with TPS65218D0 user guide"?
    This means that RTC disable mode cannot be selected, is this understanding correct?

  e2e.ti.com/.../890446

Best regards,
Kanae

  • 0
    TI__Mastermind 30310 points

    Kanae said:
        -RTC_KALDO_Enn: Any AM437x 1.8 V power supply -> VDDS_RTC
    　-PMIC_POWER_EN : RTC_PMIC_EN -> NC

    LDO1=1.8V, and this is the only 1.8V supply on the TPS65218D0 PMIC when DCDC6 is not used.

    This is an acceptable wiring for TPS65218D0 device if the RTC supplies (DCDC5 and DCDC6) will be un-used:

  • 0 in reply to Brian Berner
    Guru 10105 points


    Hi Brian.

    Thank you for your reply.

    Regarding Q1, I found out that if I want to use RTC disabled,
    I can design it as per Figure 6-2 without using DCDC5/6.

    Also, I would like to confirm about changing the following pins as shown in the checklist.

    -PMIC_POWER_EN: RTC_PMIC_EN-> NC

    In the 5.2 Functional Block Diagram of the TPS65218D0 datasheet, it says "SoC - > PWR_EN".
    Is there a reference schematic for "PWR_EN" when it is not connected to SoC?

    For Q2, is it correct that the 10KΩ resistor is unnecessary as shown in Figure 6-2?

    Best regards,
    Kanae

  • 0 in reply to Kanae
    TI__Mastermind 30310 points

    Kanae,

    Kanae said:
    -PMIC_POWER_EN: RTC_PMIC_EN-> NC

    You can leave the PMIC_POWER_EN pin on the processor side as NC.

    However, you cannot leave the PWR_EN pin on the PMIC side as NC. You will need to connect the PWR_EN pin of the TPS65218D0 to your main power supply (5V) through a pull-up resistor.

    In the schematic image that you shared, R86 is the pull-up to 5V and R101 is not populated (it can be removed).

    Kanae said:
    For Q2, is it correct that the 10KΩ resistor is unnecessary as shown in Figure 6-2?

    Yes, this is correct. The 10k resistors (R26, R55, R47, R28, and R45) are not needed. You can remove and short the following pins directly to GND: L5, L6, FB5, FB6, and IN_BU. 

    R60 should be not populated (or removed) because PGOOD_BU can be left floating.

  • 0 in reply to Brian Berner
    Guru 10105 points

    Hi Brian,

    Thank you for your support.

    My customer will modify the board to reflect the above information.

    Best regards,
    Kanae