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TPS65218: Ah of coin cell , DCDC5

David Kim2
Genius 3385 points
Part Number: TPS65218


Hi

I have the following questions about TPS65218.

1. Can you recommend the Coin cell specification that connects to CC pin? (ex. 3.7V/ ?Ah)

2. I won't use DCDC5. How do I connect the pins?(open or connection gnd ?)

Thanks 

  • 0
    TI__Mastermind 32220 points

    Hi David, 

    Thank you for reaching out via E2E. Please see my comments below in regards to your questions. 

    1) Referring to TPS65218D0 datasheet section 7 "Power Supply Recommendations" the device is designed to operate with a backup input voltage at CC pin between 2.2V and 3.3V. The input should be a coin cell battery with a 3V nominal voltage. We do not recommend any specific charge capacity, but you can expect the coin cell capacity to be in the range of mAh. Selecting a coin cell with a higher capacity will lead to longer lifetime.

    2) If you were planning to not use either DCDC5 and DCDC6 then all related pins are recommended to be tied to ground as shown on page 93 of the TPS65218D0 datasheet. If you plan to not use DCDC5 it will make no difference whether you leave L5 and FB5 pins connected to ground or floating.

    Please be aware in either situation the PGOOD_BU output pin will be driven low because DCDC5 will not be in regulation. Further information on PGOOD_BU output can be found on TPS65218D0 datasheet on page 28 and I have included below. Also DCDC5 can be disabled following power up via I2C write to ENABLE1 register (address 0x11) bit 4. 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Genius 3385 points

    Hi

    I have additional question as below.

    Dose the TPS65218 have a coin cell charging function?

    Thanks

  • 0 in reply to David Kim2
    TI__Mastermind 32220 points

    Hi David, 

    Yes the TPS65218 has the coin cell backup battery supply function. It is described in further detail in section 7.3.1.12 of the TPS65218 datasheet on page 36. 

    Please note that as shown on the TPS65218 product page on TI.com the TPS65218 is not recommended for new designs. TI recommends using the newer TPS65218D0, which I mention in my previous answer above, instead. 

    Best Regards,

    Garrett