The MAX1462 implements a revolutionary concept in signal conditioning, where the output of its 16-bit analog-to-digital converter (ADC) is digitally corrected over the specified temperature range. This feature can be readily exploited by industrial and medical market segments, in applications such as sensors and smart batteries. Digital correction is provided by an internal digital signal processor (DSP) and on-chip 128-bit EEPROM containing user-programmed calibration coefficients. The conditioned output is available as a 12-bit digital word and as a ratiometric (proportional to the supply voltage) analog voltage using an on-board 12-bit digital-to-analog converter (DAC). The uncommitted op amp can be used to filter the analog output.
The analog front end includes a 2-bit programmable-gain amplifier (PGA) and a 3-bit coarse-offset (CO) DAC, which condition the sensor's output. This coarsely corrected signal is digitized by a 16-bit ADC. The DSP uses the digitized sensor signal, the temperature sensor, and correction coefficients stored in the internal EEPROM to produce the conditioned output.
Multiple or batch manufacturing of sensors is supported with a completely digital test interface. Built-in testability features on the MAX1462 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 of calibration and compensation coefficients determined from transducer pretest data.
- Final test operation: Verification of transducer calibration and compensation, without removal from the pretest socket.
The MAX1462 evaluation kit (EV kit) allows fast evaluation and prototyping, using a piezoresistive transducer (PRT) and a Windows®-based PC. The user-friendly EV kit simplifies small-volume prototyping; it is not necessary to understand fully the test-system interface, the calibration algorithm, or many other details to evaluate the MAX1462 with a particular sensor. Plug the PRT into the EV kit, plug the EV kit into a PC parallel port, connect the sensor to an excitation source (such as a pressure controller), and run the MAX1462 EV kit software. An oven is required for thermal compensation.