Micronas Slashes Cost and Qualification Time With Fully Programmable Hall Effect Switch for Automotive Applications (0304)

Freiburg, Germany -February 19, 2003- Micronas, a leading supplier of IC solutions for multimedia, consumer and automotive electronics, introduced the HAL 1500, a fully programmable hall switch aimed at automotive applications requiring position sensing like sunroofs, windows, seat positions and safety belts.

"Until now manufacturers were using a great variety of different sensors with fixed switching levels and output modes to fulfill the different demands of various applications. The HAL 1500 covers all applications with one fully integrated switch, which significantly reduces costs," said Peter Zimmermann, automotive market manager at Micronas. "This also means that now only one qualification process is needed for each single switch."

The fully integrated switch allows system manufacturers to program magnetic switching levels and output modes through simple end-of-line programming of the on-chip EEPROM. The switch acts as a unipolar or latching switch with normal or inverted output, making rotation measurements possible to detect, as in the rotation of camshafts, for example.

"Due to its programmability, the switch offers greater flexibility and a much higher accuracy than fixed-function devices. This allows Micronas to access and expand into new markets for hall effect switches," added Zimmermann.

Higher accuracy is a key issue for many applications in the car such as seat position sensing in conjunction with car safety systems. With position sensing information, the airbag controller knows the exact location of the driver or passenger and can compute how fast the airbag must be deployed to provide optimal protection in case of an accident.

The HAL 1500 features an on-chip sensor element, DSP and EEPROM. With the help of the data stored in the EEPROM, the DSP computes the behavior of the switch. Non-programmable switches have wide-spread magnetic switching levels due to the variations in the production process. To avoid these part-to-part variations each individual sensor can be adjusted in the HAL 1500 to meet the demands of each application. As a result of the sensors' programmability, production variations are no longer problematic and the manufacturer's application is much more accurate.

Where moderate resolution is required, it is possible to program the HAL 1500 as a pseudo linear hall sensor. The PWM output signal delivers a 4-bit resolution, which is enough for applications like four-level regulation of the headlight and multi-level wiper regulation. As a pseudo linear hall sensor, the HAL 1500 is the device of choice for cost sensitive applications where high 12-bit resolution is not required. For applications requiring higher bit resolution, Micronas offers the HAL 8xx families of regular linear hall sensors.

The HAL 1500 switch is available in SOT89-SMD and TO92UA through contact packages. In high quantities of 1 million and up, the sensors sell for US$0.75 each.

Glossary

Unipolar Hall Switch: These types of switches require a single polarity magnetic field for operation (a south pole or a north pole). When the magnetic flux density increases above the operating point, it switches on.

Latching Hall Switch: These switches need both north and south pole for operation. If no magnetic field is sensed the switch remains in its last position.

Inverted output: Normally the sensor switches from high to low if B > Bon. A switch with an inverted output switches from low to high if B > Boff.