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BQ25703A: BQ25703A How to get Device Power when Battery mode ??

March Jasper
Expert 2340 points
Part Number: BQ25703A

Hi 

Our customer has some question for BQ25703A.

[ Question ] 

  How to get  Device Power   when Battery mode  with  BQ25703A  ?

   *  If device disconnect  AC Adapter power and Battery only connect . 

  Which Pin or  other ??

Thanks  and Regard

March Jasper  (  Disty  Sugimoto ) 

  

  • 0
    TI__Expert 3320 points

    Let me clarify the question:

    Are you asking about how to monitor system power in battery only mode?  Or you are asking about our 25703 device power consumption?

    Regards

    Shishuo

  • 0 in reply to Shishuo Zhao
    Expert 2340 points

    Hi  Shishuo

    Thank you very much this replay.

    ＞Are you asking about how to monitor system power in battery only mode? 

    ＞Or you are asking about our 25703 device power consumption?

    Yes , I asking  about this one   " how to monitor system power in battery only mode?  ".

    Regard 

    March Jasper  (  Disty  Sugimoto ) 

  • 0 in reply to March Jasper
    TI__Expert 3320 points

    Hi March:
     

        You can use pin 10 for system power monitor. It is a current mode system power monitor. The output current is proportional to the total power from the adapter and the battery. The gain is selectable through SMBus. Place a resistor from PSYS to ground to generate output voltage. This pin can be floating if not in use. Its output voltage is clamped below 3.3 V. Place a capacitor in parallel with the resistor for filtering.

    The ratio of PSYS pin current and total system power, KPSYS, can be programmed in REG0x30[9] with default 1 μA/W. The input and charge sense resistors (RAC and RSR) are selected in REG0x30[11:10]. PSYS voltage can be calculated with Equation 1 where IIN>0. IBAT<0 when the battery is in forward charging with an adapter connected, and IBAT>0 when the battery is in discharging.

    VPSYS = RPSYS × KPSYS (VACP × IADPT + VSRN × IBAT )                                         (1)

    Where VPSYS is the output voltage of the PSYS pin, RPSYS is the resistance tied to PSYS pin, VSRN is the battery voltage sensed by the SRN pin, IADPT and IBAT are two current sensing outputs monitoring the adapter input current and the battery charging or discharging current.

    For proper PSYS functionality, RAC and RSR values are limited to 10 mΩ and 20 mΩ.

    Regards

    Shishuo