Hi TI expert
Could you pls help to explain how to define the formula to measure the voltage input on ADC channel.
Add more information: we want to measure one voltage with upper limit is 3.3V connect with AIN0, then which FSR shall we choose? is +-4.096?
Is the formula correct? voltage = 4.096* adc / (0.193* 4095), 0.193 is the factor of input voltage, 4095 is the Dec value for 12bits.
Thank you!
BR
Weicheng
Hi Weicheng,
Yes, for measuring up to 3.3V, +/-4.096V FSR would be the configuration you want to choose.
Just keep in mind that if supply voltage (VDD) is less than the full-scale range (4.096V), a full-scale ADC output code cannot be obtained. For example, with VDD = 3.3 V and FSR = ±4.096 V, only signals up to VIN = ±3.3 V can be measured. The code range that represents voltages |VIN| > 3.3 V is not used in this case.
For an FSR of +-4.096V, the size of an LSB is 2mV.
You can use the equation Vin = Output code * LSB size.
For example, if your input is 1V, your output code would be 500 in decimal (1V = 500 * 2mV). This output code would be represented as 0x1F4 in Hex, or 0001 1111 0100 in binary.
You can take a look at our Analog Engineer's Calculator tool ANALOG-ENGINEER-CALC Calculation tool | TI.com, This tool automatically gives you the Hex Output Code, Binary Output Code and Decimal Output Code for an input voltage, or vice versa.
Best Regards,
Angel
