MLX90323 Datasheet, PDF (22/25 Pages) Melexis Microelectronic Systems – 4 – 20 mA Loop Sensor Interface with Signal Conditioning and EEPROM

MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
11 Unique Features
Special Information
The output of the sensor bridge is amplified via offset and gain amplifiers and then converted to the correct
output signal form in one of the output stages.
The sensitivity and offset of the analog signal chain are defined by numbers passed to the DAC interfaces
from the microcontroller core (GN[9:0] and OF[9:0]). The wide range of bridge offset and gain is
accommodated by means of a 2-bit coarse adjustment DAC in the offset adjustment (CSOF[1:0]), and a
similar one in the gain adjustment (CSGN[1:0]). The signal path can be directed through the processor for
digital processing.
Programming and Setup
The MLX90323 needs to have the compensation coefficients programmed for a particular bridge sensor to
create the sensor system. Programming the EEPROM involves some minimal communications interface
circuitry, Melexis setup software, and a PC. The communications interface circuitry is available in a
development board. This circuitry communicates with the PC via a standard RS-232 serial communications
port.
12 Application Information
100 nF
5K
VDD FET VDD1
COMS
VBP
CMO
VBN
FLT
TMP
GND CMN
39 nF
75 Ohms
24 Ohms
Figure 3. Typical application schematic
Supply
100 nF 100 nF
Depends on
stability of the
current loop
Ground
3901090323
Rev 003
Page 22 of 25
Data Sheet
Feb/12