Micronas' New Sophisticated Hall Sensor To Save Up to 10 Percent Logistic Costs Compared to Potentiometers (0218)
The World's First Hall Sensor To Employ Enough EEPROM Memory And Performance To Linearize Measurement Data
Freiburg, Germany - September 24, 2002 - Micronas, the world's leading supplier of hall sensors and a leading supplier of IC solutions for multimedia, consumer and automotive electronics today announced the world's first programmable hall sensor able to linearize magnetic fields measured by the sensor element. With the HAL 855, automotive system manufacturers effectively only have to store the typical output characteristics for each application (e.g. fuel tank gauges) into the on-chip EEPROM (end of line programming).
The overall functionality of the HAL 855 allows the customers to replace various conventional potentiometers. It is well positioned for the detection of positions and angles in vehicles and industrial applications.
"The HAL 855 has an integrated EEPROM with higher memory capacity and additional logic circuitry for the computation of a range of output characteristics," commented Peter Zimmermann, automotive market manager at Micronas. "Currently, no other hall sensor on the market offers sufficient on-chip memory capacity and digital signal processing power to perform the linearization, and a purely analog approach will not solve the problem."
Since the chip is programmed only at the end of the production line, it is not necessary to support many different types of potentiometers. This makes the inventory handling much easier and reduces inventory and logistic costs dramatically.
"I believe that 10 percent of inventory costs can be saved by using the new programmable hall sensors compared to conventional electro-mechanic potentiometers" added Zimmermann.
Hall sensors offer one other significant advantage. Potentiometers measure data by making contact with the content surface and are therefore prone to wear and tear and serious corrosion. Hall sensors, however, measure the magnetic field contactless so external influences such as dirt, vibration and abrasion do not distort the measurement results. This allows the delivery of highly accurate and reliable measurement data over the entire product life cycle.
On-chip DSP circuitry does all the computing required to digitize the magnetic field and translates it according to the data stored in the EEPROM into the non-linear output data and vice versa. One example for this kind of applications are low-cost magnetic circuits (e.g. ferrites), which offer only a limited range of linearity. The HAL 855 compensates this non-linear behavior allowing mapping at an angular range of +/- 45°, a significant improvement over +/- 30° when using simple low cost magnetic circuits.
Typical application: Fuel indicators
Nearly every type of car has a proprietary tank. To enable the dashboard fuel indicator to show the fuel content, system manufacturers have traditionally deployed potentiometers, which have been tailored to every different tank type. Each potentiometer type is not only expensive to develop but also expensive for inventory handling and logistics.
Inaccurate and misleading tank indicators are a source of many car drivers´ complaints. Failures may occur for example when potentiometers are mixed up during production: if a potentiometer type is built in which does not fit the specific tank form, it delivers wrong measurement data.
An additional source of misleading data is wear: the wiper contacts are unreliable over time and even if the linearizing is done by the dashboard controller the disadvantages of the wiper contacts remain.
"With the smart hall sensor we can do all the required measurements and data processing at the very location inside the tank. Since the system manufacturers can program the specific characteristic curves at the end of their production line, they eliminate additional logistic costs and failures due to permutated potentiometers and can achieve a much higher level of accuracy and reliability", says Peter Zimmermann.
Price and Availability
The HAL 855 operates at temperatures between -40°C and +150° C (crystal temperature). Samples are available now. In high volumes the HAL 855 sells at a price of $ 1.50.