Overview
The Adafruit INA238 is a high-performance DC power monitoring breakout designed for projects that demand accurate current, voltage, and power measurements across a very wide operating range. Built around Texas Instruments’ INA238, this board supports high-side or low-side current sensing up to +85V DC, making it suitable for everything from battery-powered devices to industrial and automotive systems.
At the heart of the board is a 16-bit ADC paired with an on-board 15 mΩ, 0.1% precision shunt resistor, allowing you to measure currents up to 10A with ~0.15 mA resolution or 2.75A with ~42 µA resolution—no external shunt selection required. Along with current measurement, the INA238 continuously measures bus voltage and automatically calculates power, effectively replacing multiple multimeters with a single compact module.
Unlike simpler current sensors that are limited to low-side measurements or narrow voltage ranges, the INA238 excels in real-world designs where ground shifts, high voltages, or varying loads are involved. It offers excellent accuracy with 0.1% gain error and ±5 µV maximum offset voltage, ensuring reliable readings across a wide temperature and operating range.
The board communicates over I2C and is fully compatible with 3V or 5V logic, making it easy to use with Arduino, CircuitPython-compatible microcontrollers, and single-board computers like the Raspberry Pi. The built-in STEMMA QT / Qwiic connector enables solder-free connections and quick daisy-chaining of multiple sensors. Up to four INA238 boards can share the same I2C bus by configuring the address jumpers on the back.
Code-wise, the INA238 is fully compatible with the INA237, offering a straightforward upgrade path with improved accuracy. While it does not include built-in energy or charge accumulation like the INA228, it delivers an excellent balance of precision, capability, and cost for most DC power monitoring applications.
Specification
Technical details for Adafruit INA238 DC Current Voltage Power Monitor.
| Specification | Details |
|---|---|
| Monitor IC | Texas Instruments INA238 |
| Bus Voltage Range | 0 to +85V DC (high-side or low-side sensing) |
| Current Measurement | High-side or low-side DC current sensing |
| On-board Shunt Resistor | 15 mΩ (0.015 Ω), 0.1% precision |
| Max Continuous Current | Up to 10A (high current mode) or 2.75A (low current mode) |
| ADC Resolution | 16-bit |
| Current Resolution | ~0.15 mA/LSB (10A range) or ~42 µA/LSB (2.75A range) |
| Measured Parameters | Current, Bus Voltage, Power (calculated) |
| Interface | I2C |
| Logic Level Compatibility | 3V / 5V logic compatible |
| Connectors | STEMMA QT / Qwiic (JST SH 4-pin) + breakout pads |
| I2C Addresses | Up to 4 devices on one bus (address jumpers) |
| Notes | For DC only (not for AC); power the board from 3–5V and connect VIN+/VIN− across the load |
Pinout
| Pin / Feature | Description |
|---|---|
| VIN | Power input for the board. Supply 3V or 5V, matching your microcontroller logic level (e.g., 5V for Arduino). |
| GND | Common ground for both power and logic. |
| SCL | I2C clock pin. Connect to the microcontroller’s I2C clock line. Supports 3–5V logic with a 10K pull-up resistor. |
| SDA | I2C data pin. Connect to the microcontroller’s I2C data line. Supports 3–5V logic with a 10K pull-up resistor. |
| STEMMA QT | JST SH 4-pin connector for solder-free connection to STEMMA QT / Qwiic-compatible boards and accessories. |
| VIN+ | Positive current-sense input. Used for both high-side and low-side measurement configurations. |
| VIN− | Negative current-sense input. Connects to the load side or ground depending on configuration. |
| VBUS | Bus voltage input pin. Connects to the highest project voltage (up to 85V DC). |
| VBUS Jumper | Configures measurement mode. Closed (default) connects VIN+ to VBUS for high-side sensing. Cut the jumper to enable low-side sensing. |
| ALRT | Alert/interrupt output pin. Default state is active low. |
| Power LED | Green LED labeled ON, indicates the board is powered. Located above the STEMMA QT connector. |
| ADDR (I2C Address) | A0 Jumper | A1 Jumper |
|---|---|---|
| 0x40 (Default) | L (Open) | L (Open) |
| 0x41 | H (Closed) | L (Open) |
| 0x44 | L (Open) | H (Closed) |
| 0x45 | H (Closed) | H (Closed) |
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