The Bosch Sensortec BME280 is a digital relative-humidity, barometric-pressure, and temperature sensor with I²C and three-/four-wire SPI interfaces in a miniature metal-lid LGA package. It is commonly integrated into battery-powered environmental monitors, weather stations, and indoor-climate nodes; its temperature output also supplies compensation for the pressure and humidity measurements.
Scope: bare BME280 IC, not a breakout board with its own regulator or level shifters. Manufacturer specifications are cited; implementation recommendations are identified as engineering guidance. Research checked October 6, 2026.
1. Quick Specifications
Absolute maximum ratings are stress limits, not acceptable continuous operating conditions.
Table
Parameter
Recommended operating / typical specification
Absolute maximum / qualification
VDD, sensor supply
1.71–3.6 V; 1.8 V typical; maximum ripple 50 mV peak-to-peak.
−0.3 to +4.25 V.
VDDIO, interface supply
1.2–3.6 V; 1.8 V typical.
−0.3 to +4.25 V.
Interface-pin voltage
Logic must be compatible with VDDIO; do not assume 5 V tolerance.
−0.3 V to VDDIO + 0.3 V.
Temperature
Operating range −40 to +85 °C.
Storage −45 to +85 °C at ≤65% RH.
Pressure
Measurement range 300–1100 hPa.
0–20,000 hPa; this is not a measurement range.
Relative humidity
Stated range 0–100% RH; permitted temperature/RH combinations are qualified by the operating-envelope chart, not the entire rectangular range.
Direct liquid contact is prohibited.
Current
3.6 µA typical average at 1 Hz measuring humidity, pressure, and temperature; not a universal current for arbitrary oversampling/rates.
No absolute-maximum supply-current rating verified.
Sleep current
0.1 µA typical, 0.3 µA maximum.
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Package / pitch
8-contact LGA; 2.50 × 2.50 mm body, 0.65 mm pitch; body height 1.00 mm maximum in mechanical table.
Use the mechanical drawing, not the nominal 0.93 mm feature-summary height, for enclosure clearance.
Start-up
Maximum 2 ms to first communication after VDD >1.58 V and VDDIO >0.65 V.
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Engineering guidance: a regulated 3.3 V rail may supply both VDD and VDDIO when the host uses 3.3 V logic. A bare BME280 must not be powered from 5 V; use regulation and appropriate logic-level translation for a 5 V host.
2. Pinout & Connections
Pin numbering is clockwise in top view and counterclockwise in bottom view; check the footprint orientation before layout.
Table
Pin Number
Pin Name
Description
Best Practice
1
GND
Ground.
Tie to board GND, with a short return path.
2
CSB
SPI chip select / interface selection.
For I²C, connect directly to VDDIO. For SPI, connect to the host chip-select signal.
3
SDI
I²C SDA; SPI data input; shared data in three-wire SPI.
For I²C, connect to SDA with a pull-up to VDDIO; Bosch gives 4.7 kΩ as a normal value, subject to bus timing/load.
4
SCK
I²C SCL / SPI clock input.
For I²C, connect to SCL with a pull-up to VDDIO; size as for SDA.
5
SDO
SPI data output / I²C address selection.
I²C: tie to GND for 7-bit address 0x76 or VDDIO for 0x77. Four-wire SPI: host MISO. Three-wire SPI: do not connect.
6
VDDIO
Digital/interface supply.
Connect to a compatible logic rail; decouple to GND with 100 nF.
7
GND
Ground.
Tie to board GND; do not omit the second ground connection.
8
VDD
Analog/sensor supply.
Supply within its operating range; decouple to GND with 100 nF.
3. Standard Application Circuit
BME280 I²C wiring at 3.3 V
Use the following engineering implementation of Bosch's recommended I²C connection diagram:
Connect pin 8 VDD and pin 6 VDDIO to regulated 3.3 V; connect pins 1 and 7 to GND. These supply and ground pin functions are defined in Bosch's pin table.
Fit two 100 nF ceramic capacitors, one from VDD to GND and one from VDDIO to GND. Bosch recommends 100 nF for each; engineering guidance is to place each immediately beside its supply pin with a short ground return.
Connect CSB directly to VDDIO, SDI to host SDA, and SCK to host SCL.
Provide one SDA and one SCL pull-up to VDDIO. 4.7 kΩ each is a normal starting value, not a fixed requirement: Bosch requires selection based on bus loading and timing. Engineering guidance: account for pull-ups already fitted elsewhere on the bus, their parallel resistance, and measured rise time before changing bus speed.
Strap SDO to GND for 0x76, or to VDDIO for 0x77; use these as 7-bit addresses in the host driver. Engineering guidance: choose a definite strap rather than leaving the selection open.
For four-wire SPI, retain the two 100 nF capacitors and connect CSB, SDI/MOSI, SCK, and SDO/MISO to the host. For three-wire SPI, SDI is the shared data line and SDO is DNC; the host and sensor must be configured for the same interface.
First communication and measurement
Allow the specified start-up interval after valid supplies before communicating.
Read register 0xD0 and verify chip ID 0x60. Optional software reset is 0xB6 written to 0xE0.
Use the device's stored calibration parameters to compensate raw readings; raw register values are not directly temperature, hPa, or %RH.
Write humidity oversampling in ctrl_hum (0xF2) before writing ctrl_meas (0xF4); the humidity setting takes effect only after the latter write.
For low-duty-cycle monitoring, engineering guidance is to use forced mode: it performs one measurement and automatically returns to sleep, and must be triggered again for subsequent measurements.
After conversion completes, burst-read 0xF7–0xFE for pressure, temperature, and humidity data, then apply compensation.
Use Bosch's official BME280 SensorAPI as the firmware starting point. No LED series resistor, USB CC resistor, or differential-pair circuit applies to this IC.
4. PCB Layout & Routing Guidelines
Decoupling and return paths: Put the two recommended 100 nF capacitors close to their respective supply pins; short supply/ground loops are engineering guidance, while the capacitances come from Bosch's application circuit.
Thermal placement: Engineering guidance: keep the sensor away from regulators, MCU hotspots, power resistors, and heat-conducting copper leading from them. The internal temperature reading depends on PCB temperature, self-heating, and ambient temperature and is typically above ambient. Do not assume it is an isolated ambient-air thermometer.
Land pattern and assembly: Use Bosch's recommended Figure 21 land pattern and distinguish solder-mask-defined from non-solder-mask-defined pads. Engineering guidance: align mask, paste, and assembly capabilities with the chosen fabricator, including JLCPCB; do not substitute a generic LGA-8 footprint just because the contact count matches. Bosch specifies at least 50 µm solder height after reflow for mechanical decoupling.
Air access and lid clearance: Provide at least 0.1 mm clearance above the metal lid and appropriate housing venting for ambient-pressure measurements; prevent direct liquid contact. Engineering guidance: keep the sensing opening free of conformal coating and adhesive, and shield from strong light without sealing the vent. Bosch warns that light can affect accuracy.
Routing and thermal relief: Engineering guidance: keep I²C/SPI routes short with a nearby ground reference and avoid noisy switching nodes. No differential-pair routing or high-current trace sizing is required for these low-current sensor connections. Use thermal relief only as supported by the assembly process, avoiding long ground spokes that compromise decoupling; thermal isolation from board heat is a separate measurement-design concern.
5. Common Pitfalls / Things to Watch Out For
Treating the bare sensor like a 5 V-compatible breakout or leaving interface selection ambiguous. The supply absolute maximum is 4.25 V and interface pins are limited to VDDIO + 0.3 V; a board advertised as 5 V-compatible may contain circuitry absent from the bare IC. For I²C, connect CSB directly to VDDIO and deliberately strap SDO to select the address.
Reporting invalid or thermally biased measurements. Apply the per-device compensation parameters, write ctrl_hum before ctrl_meas, and validate readings in the final enclosure. Firmware mistakes can invalidate humidity results; poor placement can bias temperature because the sensor measures a combination of PCB heat, self-heating, and ambient conditions.
6. Popular Alternatives & Equivalents
No cross-manufacturer drop-in replacement was verified. The following verified parts provide portions of the BME280 functionality and require PCB and firmware redesign; neither is pin-compatible nor footprint-compatible with BME280.
Digital humidity and temperature, I²C; four-pin DFN, 1.5 × 1.5 × 0.5 mm.
Functionally similar for RH/T only. Does not replace pressure measurement. Change footprint, pin mapping, command handling, and driver. Exact -AD1B-R2 orderable variant is documented.
Digital absolute-pressure barometer; HLGA-10L, 2 × 2 mm body, 0.8 mm maximum height.
Functionally similar for pressure sensing only. Not an integrated RH replacement. Change footprint, wiring, and driver.
Engineering guidance: using SHT40 plus LPS22HH is a potential two-chip redesign when all three environmental measurements are required. It is not a substitute BOM line: review electrical limits, bus addresses, conversion timing, and system accuracy before committing. No Flux-library drop-in link is provided because no drop-in was verified; the links above are manufacturer product links, not claims of Flux-library availability.
7. Sourcing & Purchasing Guide
Table
Attribute
Details
Primary Distributors
DigiKey BME280 listing verified directly. Mouser BME280 listing exists but access was denied during research, so its packaging/MOQ were not confirmed. Use manufacturer-authorized channels and confirm authorization for the region.
Packaging Options
DigiKey lists Tape & Reel (TR), Cut Tape (CT), and Digi-Reel. Its SKUs are 828-1063-2-ND (TR), 828-1063-1-ND (CT), and 828-1063-6-ND (Digi-Reel). DigiKey source
Standard MOQ
DigiKey cut tape: 1 unit. Manufacturer reel quantity: 10,000 units, not the generic 3,000-unit reel sometimes assumed for ICs. This reel quantity is not a universal MOQ for every distributor. DigiKey source
Sourcing Advice
Engineering guidance: buy traceable stock from franchised distributors; avoid untraceable marketplace listings and verify incoming device identity and environmental response. Confirm bare IC versus breakout, manufacturer MPN BME280, Bosch SPN 0 273 141 185, LGA package, and distributor packaging SKU before ordering. Distributor CT/TR suffixes are packaging selections, not evidence of a different sensor pinout.
Availability / pricing limits
Live stock, price, lead time, and regional authorization are not guaranteed by this guide. LCSC ordering identity and availability for JLCPCB assembly were not directly verified; check those before production release.
Sources
Bosch Sensortec BME280 datasheet: revision 1.24, February 2024, document BST-BME280-DS001-24. Key sections: electrical specifications; absolute maximum ratings; compensation/registers; interfaces; pinout/application diagrams; package/land pattern; assembly; tape-and-reel. Cover revision/date verified; some extracted page footers retain earlier revision text, so identify the document by its cover.
Sensirion SHT4x datasheet, V7.3 URL: primary evidence for SHT40 function, pin assignment, package, and ordering variants. Document date not independently verified here.
STMicroelectronics LPS22HH datasheet: primary evidence for pressure-sensor function and LPS22HHTR package/ordering. Revision/date not independently verified here.
DigiKey BME280 product listing: direct distributor evidence for packaging, SKUs, cut-tape MOQ, and standard reel quantity; checked October 6, 2026.