Air Pressure Sensor 2810A/2810A EX0 pages

AIR PRESSURE SENSOR 2810A/2810A EX
A barometric pressure sensor produced for use in
hot climates and desined for Aanderaa Automatic
Weather Stations and Display Units.

The monolithic technology used in modern electronic
devices may also be used for making small pressure
sensors. Sensors made using this method have very
small hysteresis and a very low rate of ageing.
To eliminate error due to ambient temperature changes
the small sensing element can be heated to a specific
temperature before the measurement is taken.
Air Pressure Sensor 2810 utilizes a 4x4mm small silicon
chip as a sensing element. In the central area of this chip
is a thin membrane that is exposed to atmospheric
pressure on one side and to a vacuum on the other.
The membrane is furnished with 4 diffused resistors
that form a Wheatstone bridge. The output signal is
proportional to the atmospheric pressure. The chip
thus acts as an absolute pressure-sensing device.
A temperature sensing resistor and 4 heating resistors
are also diffused onto the chip. In conjunction with
an external control circuit, these resistors allow the
chip to be held at a constant temperature of 60°C
during the measurement.

The sensor consists of a PC-board with components
fastened to the sensor base and protected by a
cylindrical cover. The cover is screwed onto the base
and sealed with an O-ring. Six holes in the base provide
atmospheric pressure to the sensing element inside
the sensor.
The sensor shows outstanding performance as it has
practically no hysteresis, no temperature drift and no
ageing. It is also insensitive to mechanical acceleration
and can be operated in any position. The sensor is
waterproof.
Before measurement the sensor is heated to 60°C
and to allow enough time for temperature stabilization
the sensor should be connected to one of the last
channels in the measuring system.
Current consumption for silicon chip heating varies with
ambient temperature. At 60°C the heating current is
zero. This increases linearly as temperature decreases.
A maximum of 70 mA for heating is reached at –40°C.
The heating current is normally switched off between
readings.

D161A - Dec 2012