DA54XX_011

May 9th, 2007

5

000054xx280 ECN 927

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)

1 bar

Variometer, Altimeter, Barometer

High End Altimeter, Medical

Instrumentation

5 bar

Diving computers labelled 250 m

7 bar

Electronic Scale

Divers Watch, Tire Pressure, High End

Electronic Scale

12 bar

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.