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TPS65217: Connect to Battery

Kuan Wei Chen (Kevin Chen)
Genius 9710 points
Part Number: TPS65217

Dear Team,

I have a case with a disposable lithium battery (3.6V, can not be charged).

When I connect the TPS65217CRSLR, do I connect the lithium battery 3.6V to pin10 (AC) or to the 2pin of pin4,5 (BAT)?

Will this connection pin7,8 (SYS) be 5V output?

Thank you !!!

BR

Kevin

  • 0
    TI__Mastermind 30280 points

    Kevin,

    Connect the battery to BAT and terminate BAT_SENSE to GND with a 10k resistor. A push-button press (PB_IN toggle hi-lo-hi) is required to power-on the system.

    Output at SYS will not be 5V. The voltage at SYS will be approximately the same as the voltage at BAT, VSYS ~ VBAT.

    The connection from all inputs (AC,USB,BAT) to SYS is through load switches, not a DC-DC converter.

    SYS is used to provide input supply for DCDC1-3 and LDO1-4. All of these voltages are 3.3V or less, and with a rechargeable Li-Ion battery it is rare that the voltage would drop below 3V, so there would be no need to use a buck-boost to generate a higher voltage at SYS.

  • 0 in reply to Brian Berner
    TI__Genius 9710 points

    Dear Brian

    Thanks for the input

    Previously, when we used TPS65217, we directly connected Adaptor DC5V to pin10 (AC), and it will act on its own.

    If we change to the lithium battery and connect it to Pin4 ~ 5 (BAT), is it really need a Low trigger in Pin25 (PB_IN) so the device will work?

    BR

    Kevin

  • 0 in reply to Kuan Wei Chen (Kevin Chen)
    TI__Mastermind 30280 points

    Kevin,

    Yes, the TPS65217 powers-up automatically when AC is applied because line power means you essentially have infinite power available. Preventing immediate power-on when battery is the only supply is a power-saving feature.

    One option is to connect PGOOD (output) to PB_IN (input).

    You can directly short these pins together if there is no physical push-button available.

    Immediately after power is applied, PGOOD = low. This looks like a push-button press at PB_IN.

    When all the TPS65217 power rails are within regulation, PGOOD = high. This looks like a push-button release at PB_IN and prevents the PMIC from resetting after 8s (long key-press), which would be a problem if you short PB_IN to GND.