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Questions about INA219 Datasheet ?

Harson
Expert 3700 points
Other Parts Discussed in Thread: INA219

Hi, Team

I have some questions about the INA219 which is used by a customer BYD.

In the INA219 Datasheet: Page 18: 

Calculate the Power LSB, using Equation 5. Equation 5 shows a general formula; because the bus voltage
measurement LSB is always 4mV, the power formula reduces to the calculated result.

Power_LSB=20Current_LSB     could you explain more about this eqation?

And about  the calibration value caculate, do we have more material for explaination?

i have explained but not clear enough for customer

Thanks!

  • 0
    TI__Intellectual 2940 points

    Hello Harson,

    Attached is a document deriving the 20 to 1 ratio of the power to current LSB.  The short answer here, along with the calibration register calculation, is that these values were selected based on the internal register math for this device.

    As the INA219 actually only measures voltage, only the shunt voltage and bus voltage have preset LSB values.  The current and power values are calculated based on the voltages measured and the value entered into the calibration register which allow these corresponding LSB values be programmed based on the particular current/power range for the specific application.  The calibration register value contains both the resistor value used as well as the current LSB value and subsequently the power LSB also.

    power_LSB_INA219.pdf