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Loading issue on PMIC (TPS65910A3A1RSL) power supply lines.

kalyan kumar77
Prodigy 80 points
Other Parts Discussed in Thread: TPS65910

Hi,

In our custom build board, we are using Sitara AM3599 processor along with Power management IC (TPS65910A3A1RSL).

Initially we have not observed any issue with supplies but as part of testing we do load test on all the power supplies, then we identified issue (@ Max load) on PMIC power supply rails (VFB2&SW2-VDD2 and VFBIO&SW10-VIO).

As per the Datasheet the we should be able to load 1.5 A on VDD2 lines and 1 A on VIO line, but when we load the line for 1.5 (VDD2) and 1A (VIO) we have observed  the drop in supply voltage.

After complete referring the data sheet of TPS65910A3A1RSL we understood that Max load of line can be configured through EEPROM register values.

We have read the REF_REG of line VIO and VDD2 and understood that lines have been configured for 0.5A with 1.5V for VIO  and 1 A with 1.1V for VDD2.

 

Description (Address)

Register values (Data Read)

Data Supposed to be (for required load)

VDD2 control register (0x24)

0x05 (1.1V ,1A)

0x25 (1.1V, 1.5A)

VIO control register (0x20)

0x01 (1.5V, 0.5A)

0x04 (1.5V, 1A)

 

We want the lines VIO and VDD2 to be configured permanently for max load possible , could you help us on this.

  • 0
    TI__Guru**** 161600 points
    Hi,

    Are you running some OS, while you do your load tests?
    You can do I2C writes in u-boot code board/ti/am335x/board.c in the am33xx_spl_board_init() function, in order to update the corresponding PMIC registers.

    If you do your load tests at kernel stage, you can use u-boot user space commands i2c mm to modify the pmic registers. If you choose this option, you may have to write these registers on every system restart.

    Best Regards,
    Yordan
  • 0
    TI__Genius 10000 points
    Kalyan,

    Hi, you cannot change the startup configurations (EEPROM) of the device. The device will always have the same startup sequences/voltages. Once the device is on, you can configure the voltages as you need - as Yordan has explained.

    For recommendations on setting up the TPS65910 with AM3599, check out this user guide: www.ti.com/.../swcu093e.pdf

    Please let me know if you need further assistance.

    Thanks,
    Nastasha
  • 0 in reply to Nastasha
    Prodigy 80 points
    Hello Natasha,

    We are not trying to change the voltage or sequence.

    While doing the electrical validation of our design with PMIC, we found PMIC is not supporting the load current as mentioned in the user guide for two of the rails (VIO and VDD2).

    I could not add the attachment here , please refer the page no 6 of the user guide, which clearly states that lines (VIO and VDD2) can handle 1 A and 1.5 A




    Regards
    N Kalyan
  • 0 in reply to kalyan kumar77
    TI__Genius 10000 points
    N Kaylan,

    Thank you for the clarification. What external components do you have on these two rails?

    Regards,
    Nastasha