BMP390 Pressure Sensor Interface
Overview
Interface circuit for BMP390 digital barometric pressure sensor with I2C communication protocol and power conditioning. The sensor is configured for I2C operation with address selection via SDO pin.
Bill of Materials
| Reference |
Component |
Value |
Package |
Description |
| U14 |
BMP390 |
- |
HLGA-10 |
Barometric pressure sensor |
| C61 |
Capacitor |
1µF |
0603 |
VDD decoupling capacitor |
| C62 |
Capacitor |
1µF |
0603 |
VDDIO decoupling capacitor |
| R81 |
Resistor |
10kΩ |
0603 |
CSB pull-up resistor |
Pinout and Connections
BMP390 (U14) Pin Configuration
| Pin |
Symbol |
Function |
Connection |
Notes |
| 1 |
VDDIO |
I/O Supply |
3.3V via C61 |
I2C interface power |
| 2 |
SCK |
Serial Clock |
I2C_SCL |
I2C clock input |
| 3 |
VSS |
Ground |
GND |
Ground reference |
| 4 |
SDI |
Serial Data In |
I2C_SDA |
I2C data line |
| 5 |
SDO |
Serial Data Out |
GND |
I2C address select (0x76) |
| 6 |
CSB |
Chip Select |
3.3V via R81 |
I2C mode enable (HIGH) |
| 7 |
INT |
Interrupt |
DNC |
Do Not Connect per datasheet |
| 8 |
VSS |
Ground |
GND |
Ground reference |
| 9 |
VDD |
Core Supply |
3.3V via C62 |
Main power supply |
| 10 |
GND |
Ground |
GND |
Ground reference |
Power Supply Configuration
- Supply Voltage: 3.3V common rail for both VDD and VDDIO
- VDD Range: 1.8V - 3.6V (core supply)
- VDDIO Range: 1.2V - 3.6V (I/O supply)
- Decoupling: 1µF ceramic capacitors on both supply pins
Power Consumption
| Operating Mode |
Typical Current |
Supply Voltage |
Power |
| Sleep Mode |
0.2 µA |
3.3V |
0.66 µW |
| Standby Mode |
1.8 µA |
3.3V |
5.94 µW |
| Normal Mode @ 1Hz |
3.4 µA |
3.3V |
11.2 µW |
| Forced Mode (single conversion) |
~500 µA |
3.3V |
1.65 mW |
| Peak Current (during conversion) |
714 µA |
3.3V |
2.36 mW |
Additional Power Notes:
- Startup Current: Brief spike during power-on (~1mA for ~2ms)
- I2C Activity: Minimal additional current during communication
- Pull-up Resistor (R81): 3.3V/10kΩ = 330µA when CSB active
I2C Interface Setup
- Protocol: I2C slave device
- Slave Address: 0x76 (SDO tied to GND)
- Alternative Address: 0x77 (if SDO tied to VDDIO)
- Bus Speed: Supports 100kHz (standard) and 400kHz (fast mode)
- Pull-up Resistors: Implemented elsewhere in system on SCL/SDA lines
- Mode Selection: CSB pulled high via R81 enables I2C communication
Interface Signals
- I2C_SCL: Serial clock line to microcontroller
- I2C_SDA: Serial data line to microcontroller
- BMP390_INT: Interrupt output (currently unused, DNC per datasheet)
Design Notes
- Thermal Placement: Component positioned away from heat sources for accurate readings
- Single Supply: VDD and VDDIO connected to same 3.3V rail (datasheet compliant)
- Address Configuration: SDO grounded for 7-bit address 0x76
- Unused Pins: INT pin left disconnected as recommended by datasheet
- Communication Mode: CSB high selects I2C over SPI interface
Operational Characteristics
- Pressure Range: 300 - 1250 hPa (equivalent to +9000m to -500m altitude)
- Temperature Range: -40°C to +85°C
- Resolution: 0.0016 hPa (0.013m altitude resolution)
- Interface: I2C up to 400kHz
- Power Modes: Sleep, forced, and normal measurement modes
Register Access
- Default State: Sleep mode after power-on reset
- Calibration: Factory calibration coefficients stored in NVM
- Configuration: All sensor parameters configurable via I2C registers
- Data Format: 20-bit pressure, 20-bit temperature values