MAX1457 Maxim, MAX1457 Datasheet - Page 8

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

Compensation requires an examination of the sensor
performance over the operating pressure and tempera-
ture range. Use two test pressures (e.g., zero and full-
span) and two temperatures. More test pressures and
temperatures will result in greater accuracy. A simple
compensation procedure can be summarized as follows:
Set reference temperature (e.g., +25°C):
1) Initialize each transducer by loading its EEPROM with
2) Set the initial bridge voltage (with the FSO DAC) to
0.1%-Accurate Signal Conditioner
for Piezoresistive Sensor Compensation
8
Figure 5. Basic Ratiometric Output Configuration
default coefficients (e.g., based on mean values of
offset, FSO, and bridge resistance) to prevent gross
overload of the MAX1457.
half the supply voltage. The bridge voltage can be
_______________________________________________________________________________________
0.1 F
*OPTIONAL PULL-UP RESISTOR
SENSOR
+5V
Sensor Compensation Overview
0.1 F
V
ORG
V
DD
SS
93C66 SO-8
EEPROM
CLK
CS
DO
DI
R
50k
0.1 F
ISRC
LINDACREF
+5V
BDRIVE
AGND
AMP+
5k*
AMP-
ECLK
R
ISRC
MCS
INM
ECS
EDO
LIN
INP
EDI
(OPTIONAL)
R
STC
V
V
DD
SS
12-BIT ADC
INTERFACE
CURRENT
SOURCE
EEPROM
SERIAL
V
DD
V
DD
MAX1457
PGA
3) Calibrate the transducer’s output offset and FSO
4) Store calibration data in the test computer.
Set next test temperature:
5) Calibrate offset and FSO using the OFFSET TC and
6) Store calibration data in the test computer.
Repeat steps 5 and 6 for each required test tempera-
ture.
measured by the MAX1457 and returned to the test
computer via the serial interface or by using the sys-
tem digital voltmeter to measure the voltage on either
BDRIVE or VBBUF.
using the OFFSET and FSO DACs, respectively.
FSO TC DACs, respectively.
OSCILLATOR
GENERATOR
V
BDRIVE
BIAS
V
SS
OP AMP
+5V
A = 1
A = 1
A = 1
V
DD
NBIAS
FADJ
FOUT
VOUT
LINDAC
FSOTCDAC
OTCDAC
OFSTDAC
FSODAC
LINOUT
FSOTCOUT
VBBUF
AMPOUT
R
400k
0.1 F
BIAS
R
1.5M
OSC
5 x 0.1 F
0.1 F
0.1 F
VOUT