MAX1460 Просмотр технического описания (PDF) - Maxim Integrated
Номер в каталоге
Компоненты Описание
производитель
MAX1460 Datasheet PDF : 18 Pages
| |||
MAX1460
Low-Power, 16-Bit Smart ADC
UNCOMPENSATED SENSOR ERROR
10
8
6
4
2
0
FSO
-2
-4
-6
OFFSET
-8
-10
0
10 20 30 40 50 60 70
TEMPERATURE (°C)
CF
1µF
VDD
R1
500k
OUT
RD1
10k
UNFILTERED
BITSTREAM
AGND
RD2
10k
RF
500k
AMP-
AMP+
MAX1460
OP AMP
AMPOUT
FILTERED
ANALOG
OUTPUT
Figure 6. Sensor Characteristics Before Compensation
Figure 8. Filtering the Output DAC
COMPENSATED TRANSDUCER ERROR
0.20
0.15
0.10
0.05
FSO
0
-0.05
OFFSET
-0.10
-0.15
-0.20
0
10 20 30 40 50 60 70
TEMPERATURE (°C)
Figure 7. Compensated Sensor/MAX1460 Pair
where:
Equation (5a)
YAS
=
Signal AS
DS − DOFF
+ Of0 + Of1TA
+
Of2TA 2
Equation(5b)
Signal AL − x ⋅
1− x
Signal AS
+ Of0
+
Of1TA
+ Of2TA 2
= 0
Equation (5c)
Signal AL − x ⋅
1− x
Signal AS
+ Of0 +
Of1TA + Of2TA 2
= 0
Equations 4a and 4b form a system of two linear equa-
tions and two unknowns, G1 and G2. Solve for G1 and
G2. Equation 1 can now be readily solved for the last
unknown, Gain.
Arithmetic manipulation can magnify measurement errors
and noise. Quantization of the calibration coefficients is
another reason to consider adjusting the Gain and DOFF
coefficients. To do this, load the MAX1460 registers with
the calculated coefficients Gain, G1, G2, Of0, Of1, Of2,
and DOFF. Assuming the oven is still at temperature
C and the S sensor excitation is still applied, measure
the output DCS. Change to the L sensor excitation, and
measure DCL. Compute the new Gain coefficient using
equation 6. Remeasure DCL, and compute the new DOFF
coefficient, given by equation 7.
Equation (6)
GAINnew
=
Gain DL
D CL
−DS
− DCS
Equation (7)
DOFFnew= DOFF + DL − DCL
The final calibration coefficients may now be written into
the MAX1460 EEPROM. The unit is now ready for final
test.
www.maximintegrated.com
Maxim Integrated │ 15
Share Link: 