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TPS65910: AM3358BZCZ80 + TPS65910A3A1RSLR - VRTC power consumption issue

Dexter Choi
Expert 2795 points
Part Number: TPS65910
Other Parts Discussed in Thread: AM3358, , SN74AUP1G08

Dear Sir,

We use AM3358 + TPS65910A3A+coin-cell backup BAT(220mA 3.2V) for our board.

when main power is off, We use VRTC only mode of TPS65910A3A that backup BAT current is 253uA. so the backup BAT life time is just 1 month.

how to decrease backup BAT power consumption??

PMIC 구성 회로.pdf

  • 0
    TI__Mastermind 30280 points
    Based on Table 5.8 in the TPS65910 datasheet, titled Power Consumption, on page 17: it appears the PMIC is in the SLEEP state because it will consume ~280uA in the sleep state.

    If the PMIC was in the OFF state, with the RTC oscillator running, the current consumption would be 15-42uA.
    If the PMIC was in the BACKUP state with VBACKUP=3.2V and VBAT=0V, the current consumption is max 9uA.

    I also recommend that you switch to a rechargeable Backup Battery instead of a single-use coin cell battery. The TPS65910 has an integrated backup battery charger, which is specified in Section 5.12 Backup Battery Charger on page 19 of the datasheet.
  • 0 in reply to Brian Berner
    Expert 2795 points

    Dear Brian,

    Thank you for your reply.

    When Main power off, We found to spend 220uA power consumption of VRTC at other blocks. We refer based design for AM335x EVM schematic. (am335x_gpevm_zczbaseboard_3h0002_schematic_rev1_5c)

    could you please check to recommend solutions for decreasing power consumption.am335x_gpevm_zczbaseboard_3h0002_schematic_rev1_5c.pdf

    1. there is U1(SN74AUP1G08) at AM335xEVM, we designed same for the schematic as below picture. U1 has big power consumption as over 150uA.

    -can we remove the U1 and U6A?? There are any side effect??

    2. another block use VRTC that U25_40pin(WOL_INT) is used pull-up.

    -can we change other power source?? There are any side effect??

  • 0 in reply to Dexter Choi
    TI__Mastermind 30280 points
    Dexter,

    I will need to re-assign this post to the AM335x Sitara processor team to discuss some of the other connections on the AM335x EVM. Please allow some additional time for them to respond.
  • 0 in reply to Dexter Choi
    TI__Genius 13567 points

    Hi Dexter,

    U1 and U6A are used to create a delay in the reset release for RTC_PWRONRSTn after VRTC has enough time to ramp and reach 1.8V. You can use another method like resistor + capacitor without the AND gate.

    The VRTC pull up on WOL_INT is needed to work properly in RTC-only mode. The EXT_WAKEUP signal requires 1.8V IO signaling. Other 1.8V supplies in the system turn off in the RTC-only mode so VRTC is the only supply available to pull-up the signal.

    Regards,
    Ahmad

  • 0 in reply to Ahmad_Rashed
    Expert 2795 points

    Dear Ahmad,

    Thank you for your reply,

    I have a question for TPS65910 BBCH_REG.

    I had write BAT-UP BAT charger Enable as below location and Function. (TPS65910 BBCH_REG => 0x01(3.0V Enable))

    it looks to set Enable during booting . but it is recovery to set disable after Booting.

    hot to set this BBCH_REG and check Function.

    tps65910_probe(struct platform_device *pdev) 

    location: BSP\AM335X\Linux\linux-4.1.18+gitAUTOINC+bbe8cfc1da-gbbe8cfc\drivers\regulator\ tps65910-regulator.c

  • 0 in reply to Dexter Choi
    TI__Genius 13567 points

    Are you familiar with Linux i2c tools? It is possible to send i2c commands to the PMIC within the Linux user space to help you with debug. This register may be reset when the PMIC is powered off so configuring it at boot is needed (such as in this probe function you refer to). 

  • 0 in reply to Ahmad_Rashed
    Expert 2795 points
    Dear Ahmad,

    What is Linux i2c tools? can you give me guide document??

    Thanks.
  • 0 in reply to Dexter Choi
    TI__Genius 13567 points

    Yes there are details here: https://www.mankier.com/package/i2c-tools

    Here is an example command to read the BBCH_REG register. Where 0x2D is the PMIC address, and 0x39 is the register address. 

    i2cget -f -y 0 0x2D 0x39