DA54xx_014

June 15th, 2009

5

000054xx280 ECN 1243

APPLICATION INFORMATION

GENERAL

The MS54xx is a miniaturised absolute pressure sensor series which has been designed as a surface mount

device (SMD). Its main advantages are the high performance of the semiconductor sensor and a design which

makes it suitable for applications requiring small dimensions and cost efficiency.

The sensor element of the MS54xx consists of a micromachined silicone membrane with Pyrex glass

wafer-bonded under vacuum to the back side for reference pressure. Implanted resistors make use of the piezo-

resistive effect to sense pressure applied to the membrane. The sensor is mounted using a special process

allowing best offset stability making the device 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-Axx)

High Linearity Versions

(MS54xx-Bxx)

1 bar

Variometer, Altimeter, Barometer

High End Altimeter,

Medical Instrumentation

7 bar

Divers Watch, Tire Pressure,

Electronic Scale

High End Electronic Scale

12 bar

Pneumatic Brake, Diving Computer

70 bar

Engine Control, Diving Computer

HUMIDITY, WATER PROTECTION

MS54xx-xM with METAL CAP:

The MS54xx-AM / -BM has an anticorrosive and antimagnetic metallic 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 advisable to rinse with clean water afterwards. Special care

has to be taken not to mechanically damage the gel. Damaged gel may 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 alloy in order to avoid any galvanic effects within the end

product. The MS5401-BM is qualified referring to the ISO Standard 2281 and can withstand a pressure of 11

bar in salt water. The concentration of the sea water used for the qualification is 41 g of sea salt per 1 litre of DI

water. The MS5407-AM satisfies salt-water testing with a pressure capability of 21 bar.

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 reaching 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 may push the sensor backwards and even deform the electronic board on which the sensor is

mounted.

MS54xx-xPx with PLASTIC CAP:

The sensor die of the MS54xx-xPx is protected by a drop of silicone gel. The properties of this gel ensure

function of the sensor even in a humid environment.