This reference design uses Hall-effect sensors to implement a trigger that outputs varying voltage based on how far the trigger is pressed. These types of triggers are useful in cordless power tools or any other end equipment that uses trigger displacement information.
The design uses a contactless approach that reduces wear and tear compared to traditional mechanical-based triggers, thereby improving product lifetime. Low-power Hall-effect switches are used along with a load switch to keep the system in a low-power standby mode when the trigger is not pressed. In addition, an optional magnetic field protection feature is available that disables the voltage output when a strong, external magnetic field is present.
Features
- Up to 10 mm of trigger displacement translated to voltage
- Measured voltage error < 3% without calibration and < 0.5% with calibration
- Disables voltage output when strong external magnetic fields are detected (optional)
- Operates from AAA batteries or 5-V to 30-V external power supply
- Low system current consumption in sleep mode (3.5 µA to 6.9 µA, depending on selected protection level against external magnetic fields)