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BQ25120A: Can't exit ship mode from VIN insertion

Antony Lin
Genius 13480 points
Part Number: BQ25120A

Hi,

We have a system that there's no way to exit ship mode by MR toggling since MR is controlled by MCU which is not powered at this moment.  So, we try to exit ship mode through VIN insertion but failed.  The detail of the steps is described as below.  Please share your inputs regarding how to debug as a next step.  Thanks.

What is the voltage level of PMID/CD/MR/IN/BAT before you start to enter ship mode?

  1. PMID: 3.8V or 5V (depend on with Vin or not)
  2. CD: could not measure but FW set to high level
  3. MR: could not measure but FW set to high level
  4. IN: 0V or 5V (depend on with charge or not)
  5. BAT: 3.8V

What is test steps to enter ship mode?  Simply EN_SHIPMODE bit to ‘1’?  Is there anything else you did to enter ship mode?

  • Only enter ship mode by Simply EN_SHIPMODE bit to ‘1’

After you enter ship mode, what is the voltage level of PMID/CD/MR/IN/BAT?

  1. PMID: 3.8V
  2. CD: could not measure
  3. MR: could not measure
  4. IN: 0V (without charge)
  5. BAT: 3.8V

After you provide a valid voltage to IN trying to exit ship mode but failed, what is the voltage level of PMID/CD/MR/IN/BAT at this moment?

  1. PMID: 3.8V
  2. CD: could not measure
  3. MR: could not measure
  4. IN: 5V
  5. BAT: 3.8V

Antony

  • 0
    TI__Mastermind 21590 points

    Hello Anthony,

    Based on what you described the voltage measurement was after you entered shipmode, the device did not actually enter shipmode. 

    When the device is in shipmode, PMID and SYS should be off so voltage on those pins should be around 0V.

    What is the state of /PG upon VIN insertion?

    How is /MR controlled by MCU? /MR is pulled up to VBAT internally so it should not be connected directly to MCU.

  • 0 in reply to Raheem
    TI__Genius 13480 points

    Hi Raheem,

    Unfortunately on customer board there's no way to measure PG pin level  What else can we do to clarify this?

    Regarding MR pin connection. could you elaborate more regarding the concern to control MR from MCU side?  Now this pin is connected to MCU on this system, what can be done to prevent potential concerns?

    THanks,

    Antony

  • 0 in reply to Antony Lin
    TI__Mastermind 21590 points

    The battery voltage can be as high as 4.2V which could cause damage to the MCU gpio.

  • 0 in reply to Raheem
    TI__Genius 13480 points

    Hi Raheem,

    Currently the MR pin connected between MCU and the charger IC is not measurable, PG is not measurable either.  Could you guide me how to check why we can't enter ship mode based on the test procedure mentioned in the beginning?  And also let us know what is the what is the way to confirm we enter ship mode or not?

    In parallel, customer has another application scenario to enter Hi-Z mode by driving MR high (1.8V domain @ MCU)and driving CD low.  At this moment, they found VSYS is unexpectedly @ 3.5V (They configure 0x06 register as 0xAA to get VSYS as 1.8V).  After cross checking, they found the unexpected 3.5V @ VSYS is related to the leakage through MR pin through our internal pull-up to VBAT.  If they keep MR pin low from MCU side, VSYS is correctly at 1.8V at this moment.

    So, back to the original issue of not entering ship mode correctly.  In the previous test steps we described, their MCU drive MR high with the same way as mentioned above.  Do you think this could be related to their issue of not entering ship mode correctly?  What can we do to clarify this?  (P.S.: VSYS became 0V when they tried to enter ship mode as the previous test steps.)

    Thanks,

    Antony

  • 0 in reply to Antony Lin
    TI__Mastermind 21590 points

    Hello Antony,

    When you enter shipmode, PMID and SYS will be powered off. So PMID and SYS will be 0V when in shipmode. If VIn is present when shipmode bit is set, you'll to remove VIN for the device to enter shipmode. Also /MR must be high to enter shipmode. You can take a look at figure 15 in the datasheet.

    You can measure if input is present by monitoring the VIN_UV status bit if I2C is available. 

    /MR is normally pulled high to VBAt through internal pull up resistor. This will cause your battery voltage to backdrive your SYS voltage. This is why /MR should not be connected to MCU GPIO. 

    Since /MR is connected to GPIO which is pulled up by SYS, this could be backdriving the SYS pin and preventing device from entering shipmode.