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TPS65218D0: Queries for Interfacing with AM3352

Part Number: TPS65218D0
Other Parts Discussed in Thread: AM3352, , TPS65217

Hi Champs

There're several questions about PMIC TPS65281D0 interfacing with AM3352.

1. Accordin to PMIC datasheet, nWAKEUP needs the pull-up resistor as open-drain.
However the BBB + TPS65218D0 Reference design omitted the pull up. 
Please check if it's OK. What's TI recommendation on this?

2. What's the correct power source btw VDD_18 and VDD_3P3 which need to be connected with PGOOD' pull-up.

3. Is it possible to use other GPIO pin of AM3352 for nPFO (Power Fail Comparator Output). The pin seems to be used to monitor GPIO input status. 

The relevant pin mux changes should be done. right?

4. In the BBB reference schematic, VDD_3P3_LS, SYS_5V are connected to the connectors. What's the usage of these ?

Please see the attached schematic scratch.

PMIC_schematic_220118.pdf

5. Please also review if something is wrong from the attachment of no.4.

Thanks a lot.

Best Regards, 

Jack

  • Hi Jack,

    Thanks for reaching out! Here are the responses to your questions in the previous message:

    1. Accordin to PMIC datasheet, nWAKEUP needs the pull-up resistor as open-drain.
      However the BBB + TPS65218D0 Reference design omitted the pull up. 
      Please check if it's OK. What's TI recommendation on this?
    Are you referring to the BeagleBone Black which uses TPS65217 to power the AM335x. The PMIC WAKEUP pin does have a pull-up resistor. Its just not on the same page as the PMIC. It is in the processor page, connected to "EXT_WAKEUP". Below is a capture of the schematic. Signal "WAKEUP" comes from the PMIC. 
    • What's the correct power source btw VDD_18 and VDD_3P3 which need to be connected with PGOOD' pull-up.

    nINT, PGOOD, SCL and SDA pins on the TPS65218D0 PMIC can use the same pull-up supply. Those pull-up resistors can be connected to the same signal that is supplying VDDSHVx on the processor. This information can also be found in the following user's guide: Powering the AM335x, AM437x, and AM438x with TPS65218D0 (Rev. B)


    • Is it possible to use other GPIO pin of AM3352 for nPFO (Power Fail Comparator Output). The pin seems to be used to monitor GPIO input status. 

      The relevant pin mux changes should be done. right?

    This would be a question for the Sitara Processor team.
    • In the BBB reference schematic, VDD_3P3_LS, SYS_5V are connected to the connectors. What's the usage of these ?

    The  BeagleBone Black (BBB) uses a different PMIC (TPS65217) which has a power path integrated to chose between AC, USB or VBAT to supply the PMIC rails. The "SYS_5V" signal is the output of the power path which is connected to the input pins of all the PMIC rails (DCDC1, DCDC2, etc) and other ICs. Regarding signal "VDD_3P3_LS", I couldn't find that one in the BBB schematic. 


    Sure, I can take a look at the schematic for the PMIC connections specifically but my bandwidth is currently very limited. I can provide feedback within 5 business days. 

    Thanks,

    Brenda

  • Hi Brenda

    Thanks for your quick reply. Customer refers the BBB with TPS65218D0 schematic attached below.

    8463.TIDA-050xxx_BBB-refresh_RevE2.zip

  • Hi Jack,

    It seems like there was an issue with your last E2E post (see link below) because it was not allowing me to respond. I downloaded your .zip attachment and verified the two signals you were referring to. Signals "SYS_5V" and  VDD_3P3_LS are not needed. They were connected to the load switches on the PMIC to highlight the optional features. I'm just curious, from where did you get the design files in your attachment? 

    Link: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1073020/tps65218d0-queries-for-interfacing-with-am3352

    Thanks,

    Brenda