Diode Incorporated’s AH356xQ newest line of automotive-tough Omnipolar Hall Sensors are qualified under the Automotive Electronics Council’s AEC-Q100 Grade 0 standard. This mandates their full functionality over a wide –40°C to 150°C temperature range.
Typically, these devices are used for position and proximity sensing, open and close detection, level detection and flow metering.
The AH356xQ series of omnipolar Hall-effect switches. Image used courtesy of Diodes Incorporated.
Further specifications of the devices are detailed in the AH356xQ press release, including:
- An operating range of 3V to 28V
- HBM (human body model) ESD rating of 8kV.
- Active low outputs, open-drain outputs.
- 10µs power-up
- 3.75µs response time
The AH356xQ Family
There are three members of the AH356xQ series:
The main differences between the series members are their minimum, typical, and maximum magnetic operating points and their minimum, typical, and maximum magnetic release points. See the AH356xQ family product page for complete specifications.
According to Simon Ramsdale, Diodes Incorporated’s worldwide automotive IC marketing manager, the switches "are well-suited for automotive proximity and level-detection applications... Thanks to their Grade 0 qualification, these switches offer a great combination of performance and robustness.”
What Is the Hall Effect? What Does Omnipolar Mean?
The Hall effect comes into play when a magnetic field is applied perpendicular to a flow of electricity. The result is a charge separation, with a measurable “Hall voltage” generated as shown below.
A visual representation of Hall voltage. Image used courtesy of NPTEL (National Programme on Technology Enhanced Learning)
An omnipolar (bipolar) sensor might require proximity to the south pole of a magnet for turn-on, and proximity to the north pole of a magnet for turn off. A unipolar sensor might respond to the presence or absence of the south pole of a magnet for turn on and turn off.
The Automotive Hall-Effect Switch Landscape
- Allegro’s APS11200 is a unipolar, automotive-grade, high-temperature Hall-effect switch. The device is AEC-Q100 qualified and can actually operate at 175° for up to 500 hours. Actually developed in accordance with ISO 26262, it works with supplies ranging from 2.8 to 24V. Allegro also released a Hall-effect-based IC for angular motion detection last year.
- Silicon Labs’ S172x is a family of Hall-effect switch for the automotive market. Available for unipolar or omnipolar operation, there are six members of this family, all AEC-Q100 qualified.
- Texas Instruments’ DRV5056-Q1 is an automotive unipolar Hall-effect switch which operates from 3.3 V and 5 V power supplies. It is AEC-Q100 qualified and operates over a –40°C to 150°C ambient operating temperature range. If you'd like to read more about TI's work with the Hall-effect, they also released a Hall-effect sensor, the DRV5011.
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