pimoroni SGP41 Multi-Pixel Gas Sensor Breakout - VOC & NOx - STEMMA QT / Qwiic

AI context

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

BOARD: Adafruit product 6455, the SGP41 Multi-Pixel Gas Sensor Breakout - a Sensirion SGP41 metal-oxide (MOX) gas sensor on a small breakout with two JST-SH STEMMA QT / Qwiic sockets wired in parallel, a 5-pad 0.1 inch header (JP3), an AP2127-3.3 low-dropout regulator and a BSS138 level shifter, so a 3 V or 5 V host can talk to a 3.3 V sensor. Pimoroni resells it as SKU ADA6455 at 15.00 GBP as measured; Adafruit is the maker. Unlike the SGP40 the SGP41 has two MOX hot plates, one for VOC and one for NOx, with an on-chip controller that drives the heaters and returns two raw 16-bit signals - it is not a TVOC/eCO2 sensor like the SGP30, and Sensirion's VOC-index and NOx-index algorithms must process the raw signals.
ADDRESSES: I2C 0x59 (89 decimal), fixed - the datasheet reserves that single address and the board has no address jumper or select pin, so two SGP41s cannot share a bus without a multiplexer.
PINOUT: 5 pads on JP3. Pad 1 = VIN (power in, the fab file calls this net VCC), pad 2 = 3.3V (regulator output, up to 100 mA usable), pad 3 = GND, pad 4 = SCL (level shifted, 10 kOhm pull-up), pad 5 = SDA (level shifted, 10 kOhm pull-up). Labels are the vendor's own pin names from Adafruit's pinouts page; the fab file's nets agree (VCC, 3.3V, GND, SCL, SDA). The two STEMMA QT sockets (CONN3 and CONN4) carry the same four nets as JP3, each wired pad 1 GND, pad 2 VCC, pad 3 SDA and pad 4 SCL.
SUPPLY: VIN takes 3 V to 5 V and the regulator makes 3.3 V for the sensor and the level shifter's low side. The sensor itself is a 1.7 V to 3.6 V part (3.3 V typical) with an absolute maximum of -0.3 V to +3.6 V on both VDD and VDDH, so it must never see the raw VIN if VIN is 5 V - on this board it does not, because the regulator stands between them. Adafruit's instruction is to power VIN from the same voltage as the microcontroller's logic level.
LOGIC LEVEL: the host side follows VIN, 3 to 5 V, through the BSS138 level shifter; the sensor side is 3.3 V. SDA and SCL are pulled up on both sides by R3, a four-resistor 10 kOhm pack - two resistors to VCC for the high side and two to 3.3 V for the low side - so the bus idles at VIN, not at 3.3 V.
REFERENCE CIRCUIT: as built, from the fab file. X1 is the sensor (its footprint is named SGP30 while its value is SGP41). C4 10 uF on VIN, C5 10 uF on the regulator output, C6 0.1 uF next to the sensor, and R1 4.7 Ohm in series from the 3.3 V rail into the sensor's supply pin with C6 as its decoupling. U1 is the AP2127-3.3K. Q2 is the BSS138 level shifter. R2 10 kOhm feeds the green power LED D1, which the silk labels on. Nothing needs adding for a normal hookup: pull-ups, regulator, decoupling and level shifting are all fitted.
TRAPS: the sensor draws 6.5 mA typical and 7.2 mA maximum while conditioning at 1.8 V (4.2 mA typical at 3.3 V) and 34 uA idle, so a board powered from a GPIO pin will brown out during a measurement. Sensirion requires VDD and VDDH to be fed from the same supply; R1 4.7 Ohm is the only thing between the rail and the sensor, so do not try to inject a second supply. Data is transferred as 16-bit words each followed by an 8-bit CRC, so a driver that ignores the CRC bytes will misread every value. The sensor has an operating range of -20 to +55 degrees C and 0 to 90 percent relative humidity, non-condensing; it is not a waterproof or combustion-gas sensor. The two STEMMA QT sockets are the same nets as JP3, so a cable in each is one bus, not two.