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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

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

NBIAS

CK50

TEMP2

TEMP1

INM

INP

BDRIVE

TOP VIEW

MAX1459

SSOP

CS

DIO

AMP+

WE

FSOTC

AMP-

AMPOUT

12

11

9

10

OUT

TEMPIN

ISRC

19-1619; Rev 0; 1/00

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

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.