dfrobot OH9249 Gravity: Digital Hall Sensor

AI context

Dense context for pasting into a model prompt — addresses, pinout, voltages, tolerances and the vendor's reference circuit.

PART: DFRobot Gravity: Digital Hall Sensor, SKU SEN0185, 22 x 30 mm. A single OH9249 micropower omnipolar Hall-effect switch (SOT23, -40 to 85 C, marking GJ9) on a Gravity carrier with an onboard indicator LED. The vendor's own 'Datasheet' link serves the OH9249 data sheet, which is where the part number comes from - the product page and wiki never name the chip.
I2C ADDRESSES: none. The output is a single digital line, so buses is empty and addresses is empty; there is nothing to scan.
PINOUT: DFRobot prints three pads, GND, VCC and Signal, and numbers none of them. The entry's numbers 1-3 are the order the vendor's own pinout table lists them (GND, VCC, Signal), not a printed pad number - there is no silkscreen number to match.
SUPPLY: the module is rated 3.3 V to 5 V; the OH9249 itself runs 2.5 V to 5.5 V (3 V typical), so the module rating is the narrower one and is the one to design to.
OUTPUT AND THRESHOLDS: open digital output with a built-in pull-up resistor in the chip, so no external pull-up is needed. Awake current 2-4 mA, sleep 6-10 uA, average 10-15 uA; the part sleeps 90-120 ms at a 0.15% duty cycle, waking for 150 us with a 15 kHz chopper. Magnetic operate point 30-55 Gs for a south pole and -55 to -30 Gs for a north pole; output current 1.0 mA, saturation voltage 0.4 V at 1 mA, leakage < 0.1 uA below the release point.
ABSOLUTE MAXIMUMS: VCC 7 V, VOUT 7 V, IOUT 2 mA, supply current under fault 6 mA, junction temperature 150 C, storage -55 to 150 C, ESD 4000 V human-body / 600 V machine model. Exceeding IOUT 2 mA by pulling the output into a low-impedance load is the easiest way to kill it; drive a MOSFET or an opto rather than a relay coil directly.
REFERENCE CIRCUIT: no external parts are required - the chip's built-in pull-up plus its own sleep-awake logic means the three Gravity pins (VCC, GND, Signal) are the whole circuit, and the indicator LED is already on the board.
TRAPS: (1) It is omnipolar, so it cannot tell north from south - DFRobot says so outright, and an entry that reports 'polarity' would be wrong. (2) The output is latched between awake windows: it updates on the 90-120 ms sleep cycle, so it is not a fast edge detector. (3) The chip is micropower by design; a 4 mA awake current means it is meant to be polled, not left driving something.