MAX1459

Features:

 Highly Integrated Sensor Signal Conditioner for 2-Wire, 420mA Transmitters
 Sensor Errors Trimmed Using Correction Coefficients Stored in Internal EEPROM-Eliminates the Need for Laser Trimming and Potentiometers
 Compensates Offset, Offset TC, FSO, FSOTC, FSO Linearity
 Programmable Current Source (0.1mA to 2.0mA) for Sensor Excitation
 Fast Signal-Path Settling Time (=1ms)
 Accepts Sensor Outputs from +1mV/V to +40mV/V
 Fully Analog Signal Path
 Internal or External Temperature Reference Compensation
 Automated Pilot Production (Calibration/ Compensation) System Available
 Write Protection for EEPROM Data Security


Application

420mA Transmitters
Piezoresistive Pressure and Acceleration
Industrial Pressure Sensors
Load Cells/Wheatstone Bridges
Strain Gauges
Temperature Sensors


Pinout




Specifications

Supply Voltage, V_DD to V_SS......................................-0.3V to +6V
All Other Pins ...................................(V_SS - 0.3V) to (V_DD + 0.3V)
Short-Circuit Duration, FSOTC, OUT, BDRIVE .............Continuous
Continuous Power Dissipation (T_A = +70°C)
  20-Pin SSOP (derate 8.00mW/°C above +70°C) .........640mW
Operating Temperature Ranges
  MAX1459CAP ......................................................0°C to +70°C
  MAX1459AAP .................................................-40°C to +125°C
Storage Temperature Range ...........................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C


Description

The MAX1459 highly integrated analog-sensor signal conditioner is optimized for piezoresistive sensor calibration and compensation with minimal external components.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 transducer.Accuracies better than 0.5% can be achieved with low-cost external temperature sensors (i.e., silicon transistor),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 calibration 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.

For custom versions of the MAX1459, see the Customization section at end of data sheet.