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TPS65217: Using with a lithium-ion battery

Daniel Brown
Intellectual 870 points
Part Number: TPS65217
Other Parts Discussed in Thread: AM3358, , TPS65910, TPS65218

I am using a TPS65217C with the AM3358 just like the beaglebone reference design. I would like to know whether the the system can designed for the following uses:

- Use AC input on TPS65217C to power system and charge Li-ION battery
- When AC input is lost, switch over seamlessly to battery without losing power (without rebooting)
- AM3358 can be instructed to power down PMIC s.t. processor is powered down (no load on battery)
- When AC input reappears, system powers back up

Does the PMIC reasonably charge a single cell lithium ion battery? Any thing to watch out for? 
Is any there any way to figure out SOC other than sensing and querying voltage?

  • 0
    Intellectual 870 points
    If the TPS65217 is the not the best part for doing battery management and/or switchover from a main supply do you have any suggestion a good battery management part that can work well with the TPS65217 and AM3358 for accomplishing the above design objectives?
  • 0
    TI__Mastermind 30280 points

    Daniel,

    Answers below in RED.

    - Use AC input on TPS65217C to power system and charge Li-ION battery. Yes

    - When AC input is lost, switch over seamlessly to battery without losing power (without rebooting). Yes, assuming battery is charged above UVLO

    - AM3358 can be instructed to power down PMIC s.t. processor is powered down (no load on battery). Yes, power-down sequence can be initiated by AM335x. Will the system be running Linux? The Linux kernel for the AM335x processors contain a driver for the TPS65217 that allows the processor to control the PMIC for all system state transition.

    - When AC input reappears, system powers back up. Yes, a rising edge on AC after it has dropped to 0V completely is a wake-up event to transition out of OFF state.

    Does the PMIC reasonably charge a single cell lithium ion battery? This depends on whether the battery chemistry and capacity is compatible with the UVLO threshold and 500-mA max charge current of the TPS65217. For some customers, the answer is yes. For others, it will not work and a separate BQ battery charger from TI is needed. If you use a discrete battery charger, then you might consider the TPS65218 or TPS65910 PMICs.

    Is any there any way to figure out SOC other than sensing and querying voltage? The voltage of the battery cannot be queried. The PMIC does not have an ADC or register to display the battery voltage. The MUX_OUT pin can be configured to output the BAT voltage and connected to an ADC pin of the AM335x. If the voltage is above VOREG, then the charging current will be reduced. If the voltage is below VLOWV, the charging current will be IPRECHG. In between, the charging current is 500-mA by default.

    Any thing to watch out for? This is an open-ended question. I would recommend you read the following 2 documents and see if any of this advice is relevant to your application.