Hall Effect Sensor US1881

• Manufacturer: Melexis

The US1881 is an integrated Hall effect latched sensor. That's nice but what does it do? Holding a magnet near the sensor will cause the output pin to toggle. This makes for a robust presence sensor. A reed sensor also works nicely, but can be limited by the glass encapsulation and size. A hall effect sensor is much smaller, but can handle less current than a reed switch.

The device includes an on-chip Hall voltage generator for magnetic sensing, a comparator that amplifies the Hall voltage, and a Schmitt trigger to provide switching hysteresis for noise rejection, and open-collector output. An internal bandgap regulator is used to provide temperature compensated supply voltage for internal circuits and allows a wide operating supply range.

If a magnetic flux density larger than threshold Bop, DO is turned on (low). The output state is held until a magnetic flux density reversal falls below Brp causing DO to be turned off (high). As an example, one pole of a magnet will cause the switch to turn on, and it will remain on until exposed to the opposite pole of the magnet.

Features

• 3.5V to 24V DC operation voltage
• Low current consumption
• Temperature compensation
• Wide operating voltage range
• Open-Collector pre-driver
• 50mA maximum sinking output current
• Reverse polarity protection
• Lead Free Package: TO-92

Hooking it up

Pin	Function
1	VDD
2	GND
3	OUT

Code

Availability

• SparkFun

References

• http://www.sparkfun.com/commerce/product_info.php?products_id=9312

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