Contactless, Hall-effect variable-speed trigger reference design with external field protection


Design files


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.

  • 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)
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

Download ready-to-use system files to speed your design process.

TIDUBY9.PDF (1796 K)

Reference design overview and verified performance test data

TIDM979.PDF (239 K)

Detailed schematic diagram for design layout and components

TIDM980.PDF (122 K)

Complete listing of design components, reference designators, and manufacturers/part numbers

TIDM981.PDF (245 K)

Detailed overview of design layout for component placement

TIDM983.ZIP (1031 K)

Files used for 3D models or 2D drawings of IC components

TIDCG33.ZIP (943 K)

Design file that contains information on physical board layer of design PCB

TIDM982.PDF (615 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Linear Hall-effect sensors

DRV5056Ratiometric unipolar linear hall effect sensor with analog output

Data sheet: PDF | HTML
General-purpose op amps

TLV9061Single, 5.5-V, 10-MHz, RRIO operational amplifier for cost-optimized applications

Data sheet: PDF | HTML
Hall-effect latches & switches

DRV5032Low power (5 Hz, <1µA), low voltage (up to 5.5V) switch

Data sheet: PDF | HTML
Linear & low-dropout (LDO) regulators

TPS709150-mA, 30-V, ultra-low-IQ, low-dropout voltage regulator with reverse current protection and enable

Data sheet: PDF | HTML
Load switches

TPS229175.5-V, 2-A, 80-mΩ , 10-nA leakage load switch adj. rise time and adj output discharge

Data sheet: PDF | HTML
NAND gates

SN74AUP1G00Single 1-input, 0.8-V to 3.6-V low power NAND gate

Data sheet: PDF | HTML
NAND gates

SN74HCS004-ch, 2-input, 2-V to 6-V low power NAND gates with Schmitt-trigger inputs

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Design guide Contactless, Hall-Effect Variable-Speed Trigger Ref. Des. W/ External Field Prot PDF | HTML Dec. 17, 2021

Related design resources

Hardware development

HALL-TRIGGER-EVM Evaluation module for contactless, Hall-effect variable-speed trigger with external field protection

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