The HAL 300 and the HAL 320 are differential Hall switches produced in CMOS technology . The sensors include two temperature-compensated Hall plates with active offset compensation, a differential amplifier with a Schmitt trigger, and an open- drain output transistor.
These differential sensors respond 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 differential signal can be derived via a rotating multi-pole-ring in front of the branded side of the package (HAL 300) or via a magnet on the back side of the package generating a back-bias field at both Hall plates (HAL 320).
The active offset compensation leads to constant magnetic characteristics over sup- ply voltage and temperature . The sensors are designed for automotive and industrial applications and operate with supply voltages from 4 .5 to 24 V in the junction temperature range –40 °C up to 170 °C .
The sensors are available in the SMD package SOT89B and in the leaded version TO92UA.
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 built-in hysteresis eliminates oscillation and provides switching behavior of the output without oscillation.
Block Diagram – System Architecture
- Distance between Hall plates: 2.05 mm
- Operates from 4.5 V to 24 V supply voltage
- Switching offset compensation at 62 kHz
- Overvoltage protection
- Reverse-voltage protection at VDD-pin
- Short-circuit protected open-drain output by thermal shutdown
- Operates with magnetic fields from DC to 10 kHz
- Output turns low with magnetic south pole on branded side of package and with a higher magnetic flux density in sensitive area S1 as in S2
- On-chip temperature compensation circuitry minimizes shifts of the magnetic parameters over temperature and supply voltage range
- The decrease of magnetic flux density caused by rising temperature in the sensor system is compensated by a built-in negative temperature coefficient of hysteresis
- EMC corresponding to ISO 7637