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BQ25703A: PSYS power calculation

Christian Viala
Prodigy 10 points
Part Number: BQ25703A

Is it possible to choose a resistor off 20mOHM for input sense resistor and 10mOHM for charge sense resistor

What is the impact on PSYS measurement.

Is it possible to choose ff 50mOHM for input sense resistor and 25mOHM for charge sense resistor with parameter RSNS_RAC = 1 and RSNS_RSR = 0.

Our design have 700mA max input current and 3A max discharge current. Our important requirement is the precision on the input current limitation.

  • 0
    TI__Guru 56650 points

    bq25703A supports 20mOHM for input sense resistor and 10mOHM for charge sense resistor. Please check

    ChargeOption1 Register (I2C address = 31h) Field Descriptions bit2 and bit3; Also, check page 24:

    The charger monitors total system power. During forward mode, the input adapter powers system. During reverse OTG mode, the battery powers the system and VBUS output. The ratio of PSYS current and total power KPSYS can be programmed in REG0x31[1] with default 1 μA/W. The input and charge sense resistors (RAC and RSR) are programmed in REG0x31[3:2]. PSYS voltage can be calculated with Equation 1. For proper PSYS functionality, RAC and RSR values are limited to 10 mΩ and 20 mΩ.