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TPS65218D0: Change from TPS65218B1RSLT to TPS65218D0RSLT

Aditya Teja Damera1
Prodigy 120 points
Part Number: TPS65218D0
Other Parts Discussed in Thread: TPS65218

Hi,

We have changed TPS65218B1RSLT  to TPS65218D0RSLT  in our prototype PCB. Below is the screenshot of the Schematic.

We are not able see the voltage at output of DCDC5/DCDC6 and its related peripherals when its connected to coil cell only mode. The same code when put in EVM ( mounted with TPS65218B1RSLT  ) the Coil cell's output peripherals works fine.

Should there be any change in Hardware or the software to get it run in coin cell mode for TPS65218D0RSLT ?. Please suggest.

Thanks.

1122.PMIC.pdf

  • 0
    TI__Genius 13850 points

    Hi Aditya,

    I have assigned this thread to device expert located in USA but due to Thanks Giving holidays response might be delayed until 2nd of Dec.

    Did you changed the device TPS65218B1RSLT  to TPS65218D0RSLT by desoldering and then soldering again on same place? Just thinking can there be some solder issue?

  • 0 in reply to Jari Niemela13
    Prodigy 120 points

    Hi Jari,

    Sure, will wait for the expert's advice.Thanks for the heads up.

    For your question, No. We haven't re-soldered. We have made the change in design itself. PMIC works fine for all other conditions. But just dont work at the power down condition with coil cell connected.

    Thanks

  • 0
    TI__Mastermind 30280 points

    Aditya,

    I agree with Jari, this sounds like it could be due to an accidental soldering mistake. There is no difference in hardware or software related to the TPS65218 -B1 version vs. the TPS65218D0 for coin cell only operation.

    You can check the voltage on the CC pin by using I2C commands, in case the coin cell battery is not charged. You can also verify that FSEAL=1b. For coin cell operation, it is mandatory for the FSEAL bit to be set to 1b.

    Let me know how the debug goes. I do not think it will be difficult to determine that root cause and verify the TPS65218D0 will perform correctly in your system.

  • 0 in reply to Brian Berner
    Prodigy 120 points

    Hi Brian,

    Thanks for the input. Yes, the Fseal bit is not being set in our prototype board. But when the same code is put in our EVM board, it works and we are able to read the Fseal bit as '1' when coil cell is connected and goes back to '0' if the coil cell is removed.

    Can you please let us know what function or command is setting this Fseal bit to 1 in EVM board every time we connect the coin cell, but its not happening in our prototypes until and unless it is  manually set using the consecutive write to the password register.

    Is this Fseal bit has to be set the manually on the production board too?

    Should we have to set this FSEAL bit each time using the consecutive write commands to password register, if we remove battery and reconnect later?

    Thanks,

    Aditya Teja

  • 0 in reply to Aditya Teja Damera1
    TI__Mastermind 30280 points

    Aditya,

    Aditya Teja Damera1 said:
    But when the same code is put in our EVM board, it works and we are able to read the Fseal bit as '1' when coil cell is connected and goes back to '0' if the coil cell is removed.

    There was a bug in -B1 silicon that allowed FSEAL to flip from 0b to 1b on its own during slow ramp up on CC pin (>300us). This was caused by a flip-flop that accidentally gets set and it was fixed by design in -D0 silicon. This is the only explanation I have for the behavior you see and it is my expectation that FSEAL=0b by default.

    Aditya Teja Damera1 said:
    Is this Fseal bit has to be set the manually on the production board too?

    Yes, FSEAL means factory seal. During manufacturing in production, FSEAL = 0b to test the product and prevent coin cell battery from draining. After the final production is done with testing in production line, you set FSEAL = 1b manually to "break the freshness seal".

    Aditya Teja Damera1 said:
    Should we have to set this FSEAL bit each time using the consecutive write commands to password register, if we remove battery and reconnect later?

    In a secure application, it would be impossible to remove the coin cell battery. This is why it is so important for the FSEAL bit to be 0b during manufacturing and only "break the seal" when the product is ready to ship, because even after the product is "ready to ship" it the coin cell battery must last for at least a year before an input voltage is applied to take over as the main power supply.

    If this is not a secure application, then my answer is as follows: during initialization, you should always read FSEAL bit status. If FSEAL==0b, manually write the PASSWORD code to set FSEAL=1b. If the coin cell is not present, the code will have no effect.