AD7879 Analog Devices, AD7879 Datasheet - Page 16

• Manufacturer Part Number: AD7879
• Description: Low Voltage Controller for Touch Screens
• Manufacturer: Analog Devices

Specifications of AD7879

• Resolution (bits): 12bit
• # Chan: 6
• Sample Rate: 105kSPS
• Interface: I²C/Ser 2-Wire,Ser,SPI
• Analog Input Type: SE-Uni
• Ain Range: Uni Vdd
• Adc Architecture: SAR
• Pkg Type: CSP,WLCSP

AD7879/AD7889
Temperature Calculations
If an explicit temperature reading in degrees Celsius is required,
calculate for the single-measurement method as follows:
1.
2.
3.
4.
5.
Calculate the scale factor of the ADC in degrees per LSB.
Degrees per LSB = ADC LSB size/−2.1 mV =
(V
Save the ADC output, D
T
Take the ADC reading, D
measured, T
Calculate the difference in degrees between T
∆T = (D
Add ∆T to T
CAL
CC
.
/4096)/−2.1 mV
AMB
− D
AMB
CAL
.
.
CAL
) × degrees per LSB
CAL
AMB
, at the calibration temperature,
, at the temperature to be
CAL
and T
AMB
Rev. C | Page 16 of 40
by
Example
Using V
The ADC output is 983 decimal at 25°C, equivalent to a diode
forward voltage of 0.6 V.
The ADC output at T
Degrees per LSB = (2.5/4096)/−2.1 × 10
∆T = (880 − 983) × −0.291 = 30°C
T
AMB
CC
= 25 + 30 = 55°C
= 2.5 V as reference,
AMB
is 880.
−3
= −0.291