MLX90326

Analog 0-5V Sensor Interface IC

3901090326

Page 7 of 13

Data Sheet

Rev 002

Feb/12

6 General Description

The MLX90326 can be used with almost any type of resistive bridge sensor without the need of any

additional signal conditioning.

The differential input signal is offset compensated and amplified to achieve the desired output voltage. With a

coarse gain calibration the MLX90326 can easily accommodate sensor output spans in the 1.8mV/V to

63mV/V range to achieve 4 V output span. Sensor output offsets up to 97.2mV/V (depending on the sensor

output span and on the desired output offset) can be compensated with the coarse offset calibration to

achieve an output offset in the 0.5V to 4.5V range.

7 Unique Features

Offset canceling

The offset of amplifier DIDO is cancelled by using a chopping mechanism. Also the

amplifier DTS and all sample-and-hold circuits make use of an offset canceling mechanism. This means

that the contribution of the on-chip offsets and offset drifts is negligible compared to the external sensor

offset and offset drift.

Coarse and fine second order calibration of the sensitivity and offset.

The MLX90326 can be calibrated to achieve 4V output span for a sensor output span in the 1.8mV/V to

63mV/V and can compensate 0.4mV/V to 97.2mV/V input offset depending on the sensor output span and on

the desired MLX90326 output offset voltage. A wide range of sensor sensitivity and offset temperature drift

can be compensated with the second order fine gain and offset calibration.

EEPROM

All the calibration data is stored three times on an EEPROM and a majority voting is done when accessing

data. Parity check is used to diagnose data corruption. After all calibrations parameters were successfully

written to EEPROM, the EEPROM can be locked by sending a ‘Lock EEPROM’ command (see paragraph 6).

This is strongly recommended to avoid in application mode data corruption. For reliability reasons, actually

each calibration bit is stored three times in the EEPROM and the circuit uses a hardware majority voting

system when accessing data.