Measures barometric pressure, relative humidity, and temperature in one 2.5 mm LGA package, reporting all three over I2C or SPI. Pressure resolves to about 0.18 Pa, which tracks altitude to roughly a meter, humidity reads 0 to 100% with a fast response, and the on-chip temperature both reports ambient and compensates the other two. It runs from 1.71 to 3.6 V at a few microamps in forced mode, so it fits battery weather and altitude sensing. The three-in-one upgrade of the BMP280.

Pinout

Pin	Name	Type	Function
1	GND	power_in	Ground reference for the device. Must be tied to system ground together with pin 7.
2	CSB	input	Chip select (SPI) / interface select. Tie to VDDIO to select I2C mode; drive low to select the device during SPI transactions (4-wire or 3-wire).
3	SDI/SDA	bidirectional	Serial data input. In I2C mode this is SDA; in 4-wire SPI mode this is SDI (MOSI); in 3-wire SPI mode this is the bidirectional SDI/SDO line.
4	SCK/SCL	input	Serial clock input. Acts as SCL in I2C mode and SCK in SPI mode (3- or 4-wire).
5	SDO	bidirectional	Serial data output in 4-wire SPI mode (MISO). In I2C mode this pin sets the LSB of the 7-bit slave address (GND -> address bit 0 = 0; VDDIO -> address bit 0 = 1). Do not connect (DNC) in 3-wire SPI mode.
6	VDDIO	power_in	Digital / interface supply, 1.2 V to 3.6 V. Powers the digital I/O buffers and sets the logic levels for the I2C/SPI pins. Decouple to GND with 100 nF close to the pin.
7	GND	power_in	Ground reference for the device. Tie to system ground together with pin 1.
8	VDD	power_in	Analog / main supply for the internal sensor domains, 1.71 V to 3.6 V (typ 1.8 V). Decouple to GND with 100 nF close to the pin.

Key specifications

Parameter	Value
Type	Humidity + pressure + temperature sensor
Interface	I2C and SPI
Pressure	300-1100 hPa (+/-1 hPa abs)
Humidity	0-100% RH (+/-3% RH)
Temperature	-40 to 85 C (+/-1 C)
Supply	1.71-3.6 V
Package	LGA-8 (2.5x2.5 mm)

Ordering variants

BME280 (LGA-8, tape & reel)

CAD (KiCad official)

Symbol: Sensor:BME280 (KiCad official)
Footprint: Package_LGA:Bosch_LGA-8_2.5x2.5mm_P0.65mm_ClockwisePinNumbering
3D model: LGA-8 (KiCad packages3D, STEP)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Bosch Sensortec datasheet (60 pp, sha256 a2ccdb449fec9438, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF