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General Description
The MAX1459 highly integrated analog-sensor signal
conditioner is optimized for piezoresistive sensor calibra-
tion and compensation with minimal external compo-
nents. It includes a programmable current source for
sensor excitation, a 3-bit programmable-gain amplifier
(PGA), a 128-bit internal EEPROM, and four 12-bit DACs.
Achieving a total error factor within 1% of the sensor’s
repeatability errors, the MAX1459 compensates offset,
offset temperature coefficient (offset TC), full-span output
(FSO), FSO temperature coefficient (FSOTC), and FSO
nonlinearity of silicon piezoresistive sensors.
The MAX1459 calibrates and compensates first-order
temperature errors by adjusting the offset and span of
the input signal through digital-to-analog converters
(DACs), thereby eliminating quantization noise.
The MAX1459 allows temperature compensation via the
external sensor, an internal temperature-dependent
resistor, or a dedicated external temperature transduc-
er. Accuracies better than 0.5% can be achieved with
low-cost external temperature sensors (i.e., silicon tran-
sistor), depending on sensor choice.
Built-in testability features on the MAX1459 result in the
integration of three traditional sensor-manufacturing
operations into one automated process:
Pretest: Data acquisition of sensor performance
under the control of a host test computer.
Calibration and compensation: Computation and
storage (in an internal EEPROM) of calibration and
compensation coefficients computed by the test
computer and downloaded to the MAX1459.
Final test operation: Verification of transducer cali-
bration and compensation without removal from the
pretest socket.
Although optimized for use with piezoresistive sensors,
the MAX1459 may also be used with other resistive
sensors (i.e., accelerometers and strain gauges) with
some additional external components.
________________________Applications
4–20mA Transmitters
Piezoresistive Pressure and Acceleration
Industrial Pressure Sensors
Load Cells/Wheatstone Bridges
Strain Gauges
Temperature Sensors
Features
o Highly Integrated Sensor Signal Conditioner for
2-Wire, 4–20mA Transmitters
o Sensor Errors Trimmed Using Correction
Coefficients Stored in Internal EEPROM—
Eliminates the Need for Laser Trimming and
Potentiometers
o Compensates Offset, Offset TC, FSO, FSOTC,
FSO Linearity
o Programmable Current Source (0.1mA to 2.0mA)
for Sensor Excitation
o Fast Signal-Path Settling Time (≈1ms)
o Accepts Sensor Outputs from +1mV/V to +40mV/V
o Fully Analog Signal Path
o Internal or External Temperature Reference
Compensation
o Automated Pilot Production (Calibration/
Compensation) System Available
o Write Protection for EEPROM Data Security
Pin Configuration
Ordering Information
MAX1459
2-Wire, 4–20mA
Smart Signal Conditioner
________________________________________________________________ Maxim Integrated Products
1
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
SCLK
VDD
NBIAS
CK50
TEMP2
TEMP1
INM
INP
BDRIVE
TOP VIEW
MAX1459
SSOP
CS
DIO
AMP+
WE
FSOTC
AMP-
AMPOUT
12
11
9
10
VSS
OUT
TEMPIN
ISRC
19-1619; Rev 0; 1/00
*Dice are tested at TA = +25°C, DC parameters only.
Functional Diagram appears at end of data sheet.
EVALUATION
KIT
AVAILABLE
20 SSOP
Dice*
20 SSOP
PIN-PACKAGE
TEMP. RANGE
0°C to +70°C
-40°C to +125°C
MAX1459AAP
MAX1459C/D
MAX1459CAP
PART
For custom versions of the MAX1459, see the Customization
section at end of data sheet.