Hall Effect Sensor

The RM0435 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.
Thanks to its wide operating voltage range and extended choice of temperature range, it is quite suitable for use in automotive, industrial and consumer applications.
The device is delivered in a Thin Small Outline Transistor (TSOT) for surface mount process and in a Plastic Single in Line (TO-92 flat) for through hole mount. Both 3-lead packages are RoHS compliant. The output signal is open-drain type. Such output allows simple connectivity with TTL or CMOS logic by using a pull-up resistor tied between a pull-up voltage and the device output.
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 band gap 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 Burp causing DO to be turned off (high). The RM0435 exhibits latch magnetic switching characteristics. Therefore, it requires both south and north Poles to operate properly.