1. Overview & Function

️· Device Type: Differential Gear Tooth Sensor IC (ATS685LSH).
️· Primary Function: Detects and interprets signals from rotating gears, providing a digital output signal (current amplitude).
️· Two-Wire Operation: Operates using two wires (VCC and GND), simplifying connections.
️· Direction of Rotation: The device reads the signal when the target rotates from pin 1 to pin 4 (left to right when looking at the IC).
️· Polarity: The output signal polarity is configurable (High-Side or Low-Side sensing) affecting the voltage relative to the current flow.

2. Key Features & Operating Principles

️· Continuous Update of Switchpoints: Adaptable to variations in target position and gear shape (eccentric mounts, out-of-round gears). This is achieved through a continuous monitoring and adjustment of the switching thresholds.
️· Power-On Behavior: Starts in a high current state (I CC(High)) upon power application.
️· Initial Edge Detection/Calibration: Self-calibrates during the initial rotation, leading to a brief period of reduced accuracy (CAL I). The first three rising edges are used for Automatic Gain Control (AGC) calibration.
️· Adaptability: The device is able to adapt to changes within a gear's magnetic field.

3. Power-On & Calibration

️· Power-On State: Initially powers on in the high current state (I CC(High)).
️· Calibration Period (CAL I): Occurs after power-on, leading to temporary reduced accuracy. Uses first three rising edges for Automatic Gain Control (AGC).
️· Factors Affecting Calibration: Speed of rotation during power-on and the initial target feature position affect the CAL I period.

4. Signal Configuration & Polarity

️· Sensing Sides: Configurable for High-Side or Low-Side sensing.
️· Output Voltage (V SENSE): Voltage is determined by placement of a sense resistor (R SENSE) on either the VCC or GND pin.
️· Polarity Relationship:
- High-Side: V SENSE(HighSide) is inverted relative to I CC.
- Low-Side: V SENSE(LowSide) is in phase with I CC.

5. Technical Considerations

️· Target Rotation Direction: Critical to proper operation (pin 1 to pin 4).
️· Initialization: Brief period (CAL I) after power-up where accuracy is reduced while the device calibrates.
️· Operating Frequency: Initial edge detection is affected by the operating frequency (f OP ≤ 200 Hz).