Analog – Digital Converter Type

The general hardware configuration of A/D converter type components is shown in the figure below, where VDD is supplied from the MPU or from another power supply.

physical value
vi Sensor output signal
ai      Circuit output voltage
Conversion formula from circuit output voltage to sensor output signal value
vi = f(ai)
SP      Conversion formula from sensor output signal value to physical value
y = f(vi)

The conversion formula for vi shall be as follows.

vi = f(ai) = ai * ADC_vdd / ( 2ADC_bit )× K_tc

ADC_Vdd Sensor supply voltage [V]
ADC conversion of MPU Bit number
CAUTION:When Mbed is selected, 16bit is fixed
K_tc      Circuit/IC transformer circuit constants

The conversion formula for y is as follows.
Let it be a linear transformation equation.

y = f(vi) =( vi – x_offset ) / k_gain + y_offset

x_offset  Voltage Offset [V]
k_gain      Voltage/Physical Value Conversion Constant
y_offset     physical value Offset