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TPS65910: current specification of TPS65910.

SY Yoon
Genius 3381 points
Part Number: TPS65910
Other Parts Discussed in Thread: AM3352

Hi, 

VRTC LDO of TPS65910A3A1  doesn't have maximum current specification.

The minimum current is 0.1mA in back-up mode.

And VDDS_RTC of AM335x doesn't have minimum current specification.

If VRTC_LDO provides current to AM3352 over 5mA, is it OK? 

What is maximum current of VRTC_LDO?

  • 0
    TI__Mastermind 49231 points

    Hi, SY,

      VRTC LDO of TPS65910A3A1  doe have rated output current: IOUTmax=20mA in its active mode, and IOUTmax=0.1mA in its back-up mode; the LDO is designed to supply current for its own RTC module, not for external use.

       It's better to supply VRTC_LDO to AM3352 from another source although it should be ok to use the VRTC LDO of TPS65910A3A1; and it depends on AM3352 RTC domain application circuit design. 

  • 0
    TI__Mastermind 30310 points

    SY Yoon,

    Phil's response is correct. Please refer to TPS65910Ax User's Guide for AM335x Processors.

    For using TPS65910A3A1, refer to Figure 1. AM335x Power Supply Connections With TPS65910AA1 and TPS65910A3A1 on page 3 that shows VRTC is only used for RTC inside PMIC. VDDS_RTC on AM335x processor is powered from "External Buck".

    For using TPS65910A31A1, refer to Figure 2. AM335x Power Supply Connections With TPS65910A31A1 on page 4 that shows VRTC is used for RTC inside PMIC and to power VDDS_RTC on AM335x processor.

  • 0 in reply to Brian Berner
    Genius 3381 points

    Hi, Brian

    Thank you for your answer. I have a question.

    My Customer designed the AM3352 with TPS65910A3A1.

    VDDS_RTC on AM3352 processor is powered from VRTC like connection with TPS65910A31A1 in mass production.

    Recently, customer's board has wake-up problem at filed and he think this design is the cause.

    he can't change from TPS65910A3A1 to TPS65910A31A1 on board. 

    I am looking for a way to use TPS65910A3A1  like TPS65910A31A1 without changing the device.

    Is there a solution to solve this issue? 

  • 0 in reply to SY Yoon
    TI__Mastermind 49231 points

    Hi, SY,

      Since VRTC in TPS65910A3A1 has been set in low power mode; its max output current is 0.1 mA, it can't support VDDS_RTC of AM3352 processor, so, there is NO way to use TPS65910A3A1  like TPS65910A31A1 without changing the device.

      TPS65910A31A1 is pin to pin compatible with TPS65910A3A1, there is no change needed to use TPS65910A31A1 to replace TPS65910A3A1. 

      

  • 0 in reply to Phil Yi
    Genius 3381 points

    Hi, Phil

    Thanks.

    Your answer is right. But my customer can't change device because it's impossible.

    customer's product has already been sold in the market.

    We configure the hardware as below picture.

    VRTC is connected with PWRHOLD pin.

    Is it OK? 

  • 0 in reply to SY Yoon
    TI__Mastermind 49231 points

    Hi, SY,

      From PMIC point of view, it's barely ok to use VRTC driving PWRHOLD pin high; but, I'm not sure if it's ok from processor point of view, since the VRTC has output even in backup mode which means the PMIC will be always on. 

     Please check with processor application engineer for the PWRHOLD pin change; from the user guide that Brian linked before, processor has an output named "PMIC_PWR_EN" control the PMIC power on/off. 

  • 0 in reply to Phil Yi
    Genius 3381 points

    Hi, Phil,

    I appreciate your support.

    Thanks,