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CCS/ADC081C027: MSP430F2252

siranjeevi mahadevan
Intellectual 330 points
Part Number: ADC081C027

Tool/software: Code Composer Studio

HI ,

I M USING FOR ADC CONVERSION AND I2C BUS USING IC..MY PORBLEM IS THIS DATASHEET MENTION  ADC TRANSFER FUNCTION PAGE NO 16 HERE CONVERSION STEP SIZE IS 0.5 (Va IS 1.5)..

I CAN NOT UNDERSTAND OF THIS I APPLY FORMULA FOR (stepsize=Va/256) but this result is fully (128=0.5) here Va=128 and resultion 8-bit.how we defined Va=128mV like .1v. so its not possible?my dought here only..pls give solution..

what is Va value?

resultion=256?

stepsize value (mV).?

thanking you

siru

    

  • 0
    Genius 3255 points

    Va is your supply (which is also your reference voltage Min=2.7V max=5.5V). So, if you apply 3V at Va and have an 8-bit resolution, every step would be 3V/256 = 11.72mV (256 = 2^8 and the 8 comes from 8-bits resolution).

    The very first step (from output value 0x00 to output value 0x01) happens when Vin reaches 0.5 LSB (if your Va is 3V, this transition will happen when the input voltage at Vin reaches 5.86mV)

    All transitions after that (for example from 0x01 to 0x02) will happen at a 1 LSB further voltage increments at Vin (if your Vin is 3V, this will happen when Vin increments by a 11.72mV).

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