1. Device Overview & Functionality

️· What is it? The ATS643 is a single-chip differential Hall effect sensor IC combined with a magnet and ferrous pole piece (concentrator). It's designed to sense the rotational speed and position of gears.
️· Key Features:
- Differential Sensing: Uses two Hall elements spaced 2.2mm apart to accurately detect subtle differences in the magnetic field.
- Self-Calibrating: Adjusts itself for optimal performance.
- Temperature Compensated: Designed to minimize temperature-related errors.
- Continuous Update: The switching points (switchpoints) adjust automatically based on the signal.
- Easy Integration: Minimal external circuitry is required, reducing design time and cost.

2. Target Profiling & Sensing

️· How it Works: The ATS643 detects the magnetic profile of a rotating gear. This magnetic profile is a direct representation of the gear's physical features.
️· Figure 3: The waveform in Figure 3 shows the magnetic profile translating directly into a digital output signal.
️· Automatic Translation: The ATS643 automatically converts the gear's features into a digital signal, avoiding manual optimization.

3. Output Polarity

️· Rotation Direction: The output signal polarity depends on the direction of rotation.
- Pin 1 to Pin 4 Rotation: When rotating from the Pin 1 side to the Pin 4 side, the output goes HIGH when a tooth of the target gear is nearest the sensor.
- Pin 4 to Pin 1 Rotation: When rotating from the Pin 4 side to the Pin 1 side, the output signal polarity inverts.
️· Sense Resistor: The direction of I OUT (output current) depends on the position of the sense resistor, R SENSE.

4. Continuous Update of Switchpoints

️· Adjusting Thresholds: The ATS643 constantly adjusts its threshold levels (switchpoints) based on the incoming signal. This ensures accurate readings even with changing conditions.

5. Key Specifications & Performance

️· Operating Voltage Range: Not explicitly stated, but likely a standard range for Hall effect sensors.
️· Temperature Range: Likely a standard range, but not specified in the provided text.
️· Power Dissipation:
- TJ(max) = 165ºC; I CC = I CC(max); V CC = V CC(max). (Maximum power dissipation, see page 9 and 10 for graphs).
️· Magnetic Profile: Requires a rotating gear with a magnetic profile.
️· Target Position: Detects a relative motion to the side (pin1) or other (pin 4).



Glossary of Terms

️· Hall Effect Sensor: A type of sensor that produces a voltage proportional to the magnetic field.
️· Differential Sensing: Using two sensors to measure the difference in a signal, improving accuracy by cancelling out common-mode noise.
️· Pole Piece (Concentrator): A ferrous piece that concentrates the magnetic field, increasing sensitivity.
️· BiCMOS: A manufacturing process that combines bipolar and CMOS technologies on the same chip.
️· TJ: Junction Temperature.
️· I CC: Quiescent Current (current drawn when not actively switching).
️· V CC: Supply Voltage.
️· BOP: Break-over Point.
️· RRP: Rise Rate Point.
️· V PROC: Differential internal analog voltage.
️· R SENSE: Sense Resistor.