APPLICATION INFORMATION
GENERAL
The MS54XX is a miniaturised absolute pressure sensor series which has been designed for surface mounting
applications. Its main advantages are the high reliability of the semiconductor sensor and a design which makes
it suitable for applications requiring small-scale and cost-efficient solutions.
The sensor element of the MS54XX consists of a micromachined silicone membrane with Pyrex glass wafer-
bonded under vacuum to the backside for reference pressure. Implanted resistors make use of the piezo-
resistive effect to sense pressure applied to the membrane. The sensor is mounted in a special process
allowing best-offset stability making the part suitable for direct PCB assembly.
Typical applications for this miniaturised pressure sensor MS54XX are altitude measurements and the
measurement of atmospheric reference pressure in medical and industrial equipment as well as in automotive
and household applications, consumer electronics and pneumatics.
Full Scale
Pressure
High Sensitivity Versions
(MS54XX-AM)
High Linearity Versions
(MS54XX-BM)
High End Altimeter, Medical
Instrumentation
1 bar
5 bar
7 bar
12 bar
Variometer, Altimeter, Barometer
Diving computers labelled 250 m
Divers Watch, Tire Pressure, High End
Electronic Scale
Electronic Scale
Pneumatic Brake, Diving Computer
HUMIDITY, WATER PROTECTION
The MS54XX carries a anticorrosive and antimagnetic stainless steel protection cap filled with silicone gel for
enhanced protection against humidity. The properties of this gel ensure function of the sensor even when in
direct water contact. This feature can be useful for waterproof watches or other applications, where direct water
contact cannot be avoided. Nevertheless the user should avoid drying of hard materials like for example salt
particles on the silicone gel surface. In this case it is better to rinse with clean water afterwards. Special care
has to be taken to not mechanically damage the gel. Damaged gel could lead to air entrapment and
consequently to unstable sensor signal, especially if the damage is close to the sensor surface.
The metal cap is fabricated of special anticorrosive stainless steel in order to avoid any corrosive battery effects
inside the final product. The MS5401-BM are qualified referring to the ISO Standard 2281 and can withstand a
pressure of 11 bar in salt water. The concentration of the see water used for the qualification is 41 g of see salt
for 1 litre of DI water. The MS5405-BM and the MS5407-AM did also pass the salt-water test with a pressure
capability of 26 and 21 bar respectively.
For underwater operations as specified in ISO Standard 2281 it is important to seal the sensor with a rubber O-
ring around the metal cap. Any salt water coming to the contact side (ceramic and pads) of the sensor could
lead to permanent damage. Especially for "water-resistant 100 m" watches and for diving computers, it is
recommended to provide a stable mechanical pusher from the backside of the sensor. Otherwise the
overpressure might push the sensor backwards and even bend the electronic board on which the sensor is
mounted.
LIGHT SENSITIVITY
The MS54XX is sensitive to sunlight, especially to infrared light sources. This is due to the strong photo effect of
silicon. As the effect is reversible there will be no damage, but the user has to take care that in the final product
the sensor cannot be exposed to direct light during operation. This can be achieved for instance by placing
mechanical parts with holes in such that light cannot pass.
DA54XX_011
May 9th, 2007
5
000054xx280 ECN 927
INTERSEMA [ INTERSEMA SENSORIC SA ]
