Pinagem

Pinagem Sensor de temperatura IR sem contato MLX90614 (GY-906)

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Pinos

• VIN — board supply pin, usually fed 3.3–5V (up to ~6V) on common breakouts like the GY-906; the bare MLX90614 die itself is sold in two separate voltage grades rather than one wide range — a 3V-rated version (Vdd 2.6–3.6V) and a 5V-rated version (Vdd 4.5–5.5V) — and most breakout boards use the 3V-grade die behind their own small onboard regulator
• GND
• SCL — SMBus/I2C clock, open-drain like a normal I2C bus; needs a pull-up resistor, which most breakout boards already carry onboard
• SDA — SMBus/I2C data at a fixed default slave address of 0x5A; on factory-configured PWM-output parts this same pin instead carries a duty-cycle-encoded temperature signal rather than I2C data

Especificações

Notas

• The I2C address (0x5A by default) has no address-select pin — it's set once in EEPROM at the factory, so putting two MLX90614s on the same bus needs either reprogramming one module's address or adding an I2C multiplexer.
• Unlike a contact sensor such as the DS18B20, it reads radiated infrared rather than touching the target. The standard part has roughly a 90° field of view and about a 1:1 distance-to-spot ratio, so at any given distance it averages the temperature over a circle about that wide — background included, if the target doesn't fill the spot. Narrower-FOV variants (down to roughly 5° on some part numbers) exist specifically to shrink that spot for small or distant targets, like the ones used in no-touch clinical forehead thermometers.
• Accuracy on standard modules is typically quoted around ±0.5°C over a 0–50°C object range; the medical-grade variants used in actual clinical thermometers are tighter (around ±0.2°C) but only over a narrow band centered on body temperature, not across the sensor's full range.
• Active current draw is small (roughly 1.5–2mA typical) and the sensor can be dropped into a ~2.5µA SMBus sleep mode, but waking it back up isn't a normal I2C transaction — it needs SDA held low for tens of milliseconds first, so a driver that skips that sequence just gets no response instead of a reading.
• If the module's logic runs at 5V, SCL/SDA idle near 5V too; wiring it straight into a 3.3V-only I2C bus (an ESP32, for example) without level shifting is a common mistake — feeding the module 3.3V instead is usually the simpler fix, since the chip itself works fine well below 5V.