7.3.19.1 Digital Gain and Offset
The digital compensation implements digital gain and offset for both pressure and temperature. These are calculated based on the OFF_EN bit in the OFFSET_ENABLE register. Use Equation 2 and Equation 3 when the OFF_EN bit is 0.
Equation 2. P = P
GAIN × P ADC + P
OFFSET
where
- PGAIN is the Pressure digital gain defined by the PADC_GAIN_MSB, PADC_GAIN_LSB registers
- POFFSET is the Pressure digital offset defined by the PADC_OFFSET_BYTE1, PADC_OFFSET_BYTE0 (MSB, LSB) registers
- P is the pressure
- P ADC is the pressure digital output
Equation 3. T = T
GAIN × T ADC + T
OFFSET
where
- TGAIN is the Temperature digital gain defined by the TADC_GAIN_MSB, TADC_GAIN_LSB registers
- TOFFSET is the Temperature digital offset defined by the TADC_OFFSET_BYTE1, TADC_OFFSET_BYTE0 (MSB, LSB) registers
- T is the temperature
- T ADC is the temperature digital output
Use Equation 4 and Equation 5 if the OFF_EN bit is set to 1:
Equation 4. P = P
GAIN × (P ADC + P
OFFSET)
where
- PGAIN is the Pressure digital gain defined by the PADC_GAIN_MSB, PADC_GAIN_LSB registers
- POFFSET is the Pressure digital offset defined by the PADC_OFFSET_BYTE1, PADC_OFFSET_BYTE0 (MSB, LSB) registers
- P is the pressure
- P ADC is the pressure digital output
Equation 5. T = T
GAIN × (T ADC + T
OFFSET)
where
- TGAIN is the Temperature digital gain defined by the TADC_GAIN_MSB, TADC_GAIN_LSB registers
- TOFFSET is the Temperature digital offset defined by the TADC_OFFSET_BYTE1, TADC_OFFSET_BYTE0 (MSB, LSB) registers
- T is the temperature
- T ADC is the temperature digital output
NOTE
For high-offset sensors or sensor bridges with a low or high common mode, it may be useful to use the Offset Enabled (OFF_EN = 1) option which will cancel the offset and the amplify the values in the digital domain. The PGA305 device allows the ability to cancel the offset and amplify the signal further before being used in the compensation equation. The determination of the digital gain and offset values is implemented automatically by the PGA305 GUI.