MLX90819 Datasheet, PDF (4/11 Pages) Melexis Microelectronic Systems – Relative Integrated Pressure Sensor Datasheet

MLX90819
Datasheet
5. Functional Diagram
The pressure sensing element consists of a square diaphragm realized in the silicon chip by backside etching. The
diaphragm reacts to a pressure difference between the top and bottom side of the diaphragm. The internal str ain
increases, in particular at the border of the diaphragm. Here, the piezo -resistive elements have been implanted into
the silicon diaphragm, which act as a transducer.
The electronics front end amplifies the signal from the bridge, performs a coarse of fset compensation and an ADC
conversion. The DSP performs the compensations over temperature. Furthermore, the digital circuit provides some
filtering, the possibility to linearize the pressure signal and also implements the clamping function. The analog b ack
end consists of a 12 bit DAC and an output driver. This chip delivers an analog output proportional to the pressure or a
SENT output compliant with SAE J2716 spec dated January 2010.
A broken wire detection block allows actively driving the output to one of the rails in case of a broken supply or ground
connection. Extensive protection of the supply lines allows the MLX90819 to handle extreme overvoltage conditions
and is immune to severe external disturbances. Several diagnostic functions (over -voltage, under-voltage,
overpressure, under pressure detections) have been implemented on the 90819 and can be enabled by programming
EEPROM settings. Figure 2 describes MLX90819 block diagram.
Piezoresistive
sensing element
Temperature
Sensor
G
Diagnostic
Signals
DSP
Analog/
Digital
Regulator
Rev. Pol.
&
OverVolt.
C
M
U
X
A
D
Gain & Offset
temperature
compensation
Pressure Linearization
Programmable filter
Diagnostics Logic
D
A
Gain
RAM
EEP
ROM
Figure 2: MLX90819 block diagram
VDD
OUT
TX
(SENT)
GND
REVISION 3 – OCTOBER 20, 2016
3901090819
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