MAX1457 Maxim, MAX1457 Datasheet - Page 10

• Manufacturer Part Number: MAX1457
• Description: 0.1%-Accurate Signal Conditioner for Piezoresistive Sensor Compensation
• Manufacturer: Maxim

0.1%-Accurate Signal Conditioner
for Piezoresistive Sensor Compensation
7) Perform curve-fitting to test data.
8) Based on a curve-fit algorithm, calculate up to 120
9) Download correction coefficients to transducer
10) Perform a final test.
The resulting transducer temperature errors are limited by
the following factors:
10
Figure 7. Automated Test System Concept
Number of selected segments for compensation (up to
120).
Accuracy of the curve fitting, which depends on the
algorithm used, the number of test temperatures, and
the sensor temperature error’s shape.
Repeatability of the sensor performance. This will limit
the MAX1457’s accuracy.
sets of offset and FSO correcting values.
EEPROM.
______________________________________________________________________________________
MULTIPLEXER
DIGITAL
DVM
ECS[1:N], MCS[1:N]
ECLK
EDI
EDO
VOUT
+5V
ECS1
V
DD
MODULE 1
EDO
ECLK
ECS
EDI
V
OUT
MCS
V
MCS1
SS
Calibration and compensation requirements for a sen-
sor involve conversion of the sensor-specific perfor-
mance into a normalized output curve. An example of
the MAX1457’s capabilities is shown in Table 1.
As shown in Table 1, a repeatable piezoresistive sensor
with an initial offset of 16.4mV and FSO of 55.8mV was
converted into a compensated transducer (utilizing the
piezoresistive sensor with the MAX1457) with an offset
of 0.500V and a span of 4.000V. Nonlinear sensor offset
and FSO temperature errors, which were on the order
of 4% to 5% FSO, were reduced to under ±0.1% FSO.
The graphs in Figure 8 show the output of the uncom-
pensated sensor and the output of the compensated
transducer.
ECS2
V
DD
MODULE 2
EDO
ECLK
ECS
EDI
V
OUT
V
MCS
SS
MCS2
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• • •
• • •
• • •
• • •
• • •
• • •
Compensation Example
ECS N
V
Sensor Calibration and
DD
MODULE N
EDO
ECLK
ECS
EDI
V
OUT
OVEN
TEST
MCS
V
MCS N
SS