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AM3352: PMIC selection Recommendation for AM3352

Songzhen Guo
Intellectual 2840 points
Part Number: AM3352
Other Parts Discussed in Thread: TPS65218D0, TPS65218

Hi expert,

AM3352 is under evaluating on customer side.  There are two question need your support. I appreciate it if you can help. Thanks.

1. The max current on this VDDS_RTC is 5mA. For most external RTC, the max current always less than 1mA(such as PCF8563); Could you comment it ?

By the way, most of the RTC power supply is 3.3V. Why we choose 1.8V?

2. Do we have reference design for TPS65218D0 + AM3352 + RTC? If customer use this solution, which part in the SDK should be modified?

Could you verify if this is the appropriate solution for customer? Thanks.

There is a selection guide for AM335x:

Here are consideration from customer to choose TPS65218D0 + AM3352.

1. TPS65218D0 can support DDR3L; DDR3L will be used in customer design;

2. Temperature range need -40~105C;

3. Customer want to use DC-DC to power RTC, it can reduce power consumption;

4. In datasheet, it also recommend TPS65218D0 + AM3352:

Best Regards

Songzhen Guo

  • 0
    TI__Guru 62845 points

    I do not know the why a max current of 5mA was used in the data sheet. 

    I recently received a similar question about RTC power consumption and found some data where we measured RTC power consumption.  

    The RTC only consumes about 11uW when sourcing both supplies (1.8V and 1.1V) from external sources with the internal LDO is disabled. The RTC power consumption increases to 34uW when using a single 1.8V source with the internal LDO enabled. The difference between 34uW and 11uW, or 23uW is the potion consumed by the internal LDO.

    You may want to reference the other E2E post, where I also included two RTC power source examples that can be sourced from a coin cell battery.

    https://e2e.ti.com/support/processors/f/791/p/933504/3451826#3451826

    Hopefully this information eliminates your need for considering the other PMIC.  If not, let me know and I will try to find answers to you other questions..

    Regards,
    Paul

  • 0 in reply to peaves
    TI__Intellectual 2840 points

    Hi Paul，

    Thank you so much for your help.

     Do we have reference design for TPS65218D0 + AM3352 ? This solution is mentioned in the datasheet.

    Customer is design based on BeagleBone black development board, it's a reference design from TI. Here is the link: https://www.ti.com/tool/BEAGLEBK?keyMatch=BEAGLEBONE&tisearch=Search-EN-everything&usecase=GPN

    When customer want to change the PMIC to TPS65218D0, do we need change the SDK of AM3352? If we need change, which part need to change? Could you give a guide for us? Thanks.

    Best Regards

    Songzhen Guo

  • 0 in reply to Songzhen Guo
    TI__Guru 62845 points

    I ask around to see if anyone was aware of a TI board design that used AM335x with TPS65218D0. I was not able to find a design which you could reference. However, I was told other customers have used AM335x with TPS65218D0. You may want to search both AM335x and TPS65218 E2E forums looking for any relevant posts where other customers have discussed this combination of devices. 

    I do not have any experience with software support, so I will need to point you to someone else to answer your question about changing the SDK. Which SDK are you using Linux or RTOs, so I know how to direct your question.

    Regards,
    Paul

  • 0 in reply to peaves
    TI__Intellectual 2840 points

    Hi Paul,

    Thank you so much for your help.

    After communication with customer, I find they are using Linux now. Could you help us to verify the SDK modification? Thanks.

    Best Regards

    Songzhen Guo

  • 0 in reply to Songzhen Guo
    TI__Guru 62845 points

    I will re-assign this thread to someone on the Linux software team.

    Meanwhile you may want to read the an E2E post from the PMIC team, where they just posted a Beagle Bone Black schematic that uses TPS65218D0 to power the AM335x device.

    https://e2e.ti.com/support/power-management/f/196/p/946924/3499187#3499187

    Regards,
    Paul

  • 0 in reply to Songzhen Guo
    TI__Guru**** 167361 points

    Hi Songzhen,

    To configure TPS65218 in Linux kernel, you only have to define the PMIC in kernel device tree file. The AM437x GP EVM uses TPS65218, so you can use its board device tree as a reference, please check kernel file arch/arm/boot/dts/am437x-gp-evm.dts.