The HAL^® 320 is a differential Hall switch produced in CMOS technology. The sensor includes two temperature-compensated Hall plates (2.25 mm apart) with active offset compensation, a differential amplifier with a Schmitt trigger, and an open-drain output transistor.

The HAL 320 is a differential sensor which responds to spatial differences of the magnetic field. The Hall voltages at the two Hall plates, S₁ and S₂, are amplified with a differential amplifier. The differential signal is compared with the actual switching level of the internal Schmitt trigger. Accordingly, the output transistor is switched on or off.

The sensor has a bipolar switching behavior and requires positive and negative values of ΔB = B_S1 - B_S2 for correct operation.

The sensor is designed for industrial and automotive applications and operates with supply voltages from 4.5 V to 24 V in the ambient temperature range from –40 °C up to 150 °C.

The HAL 320 is an ideal sensor for target wheel applications, ignition timing, anti-lock brake systems, and revolution counting in extreme automotive and industrial environments

The HAL 320 is available in the SMD-package SOT89B-2 and in the leaded versions TO92UA-3 and TO92UA-4.

System Architecture

This Hall effect sensor is a monolithic integrated circuit with 2 Hall plates 2.25 mm apart that switches in response to differential magnetic fields. If magnetic fields with flux lines perpendicular to the sensitive areas are applied to the sensor, the biased Hall plates force Hall voltages proportional to these fields. The difference of the Hall voltages is compared with the actual threshold level in the comparator. The temperature-dependent bias increases the supply voltage of the Hall plates and adjusts the switching points to the decreasing induction of magnets at higher temperatures. If the differential magnetic field exceeds the threshold levels, the open drain output switches to the appropriate state. The builtin hysteresis eliminates oscillation and provides switching behavior of the output without oscillation.

HAL 320 block diagram

Main Features