DA5541B_005.doc

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00005541766 ECN865

APPLICATION INFORMATION

GENERAL

The advantage for this combination of a sensor with a directly adapted integrated circuit is to save other external

components and to achieve very low power consumption. The main application field for this system includes

portable devices with battery supply, but its high accuracy and resolution make it also suited for industrial and

automotive applications. The possibility to compensate the sensor with a software allows the user to adapt it to

his particular application. Communication between the MS5541B and the widely available microcontrollers is

realised over an easy-to-use 3-wire serial interface. Customers may select which microcontroller system to be

used, and there are no specific standard interface cells required, which may be of interest for specially designed

4 Bit-microcontroller applications.

CALIBRATION

The MS5541B is factory calibrated. The calibration data is stored inside the 64 Bit PROM memory.

SOLDERING

Please refer to the application note AN808 for all soldering issues.

HUMIDITY, WATER PROTECTION

The silicon pressure transducer and the bonding wires are protected by a anticorrosive and antimagnetic

protection cap. The MS5541B carries a metal 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 protection cap is fabricated of special anticorrosive and antimagnetic stainless steel in order to avoid

any corrosive battery effects inside the final product. The MS5541B was qualified referring to the ISO 6425

standard and can withstand a pressure of 21 bar in salt water. The concentration of the see water used for the

qualification is 41 g of see salt for 1 liter of DI water.

For underwater operations like specified in ISO 6425 standard it is important to seal the sensor with a rubber O-

Ring around the metal Ring. Any salt water coming to the contact side (ceramic and Pads) of the sensor could

lead to permanent damage. For "water-resistant" watches 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 MS5541B is protected against sunlight by a layer of white gel. It is, however, important to note that the

sensor may still be slightly 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.

CONNECTION TO PCB

The package outline of the module allows the use of a flexible PCB to connect it. This can be important for

applications in watches and other special devices, and will also reduce mechanical stress on the device.

For applications subjected to mechanical shock, it is recommended to enhance the mechanical reliability of the

solder junctions by covering the rim or the corners of MS5541B's ceramic substrate with glue or glob top-like

material.