Hardware Overview
Let's take a closer look at the INA228 and INA237 and other hardware present on these Qwiic breakouts.
INA228 and INA237 Digital Power Monitors
The INA228 monitors voltage, power, die temperature as well as energy and charge accumulation with 20-bit delta-sigma analog-to-digital converter (ADC). For complete information on the INA228, refer to the datasheet.
The INA237 monitors voltage, power and die temperature with a 16-bit delta-sigma analog-to-digital converter (ADC). For a complete overview of the INA237, refer to the datasheet.
Both INA2XX sensors have a common-mode range of -0.3 V to 85 V and a bus voltage sensing range of 0 V to 85 V. When measuring differential voltage the sensors have a default range of ± 163.84mV and a reduced range of ± 40.96 mV. The default range allows for measuring larger current values (up to 10A with the default shunt resistor) where the reduced range allows for a 4x finer resolution at the expense of a smaller maximum current value. The INA228 and INA237 communicate over a high-speed 2.94 MHz I2C interface and both boards set the default I2C address to 0x40.
Connectors
Load and Bus Connection Screw Terminal
A 3-pin screw terminal handles connections to the INA2XX's load and bus inputs. These pins are labeled IN+, IN- and VBUS. The load current flows from the IN± through the 15mΩ shunt resistor. With the default shunt resistor, the max rating across the IN± pins is 10A@85V when using the default range. The board defaults to isolate VBUS from the inputs but it can be tied to IN+ by closing the VBUS jumper. Read on to the Solder Jumpers section for more information.
Qwiic Connectors
A pair of Qwiic connectors make it easy to power and communicate with the board with no soldering. These connectors provide power (3.3V/GND) and I2C (SDA/SCL) to the board.
PTHs
There are two plated through-hole pins located just below screw terminal that let users solder a custom shunt resistor to the board in place of the default 15mΩ shunt resistor. If you opt to solder a different shunt resistor, make sure to open the SHUNT jumper on the back side of the board to bypass the default resistor.
The board also has a 0.1"-spaced plated through-hole header to make connections to the INA2XX's power (3.3V and Ground), I2C bus (SDA/SCL) and Alert pin. The alert pin is an open-drain output that can be configured to trigger for various threshold conditions. These include shunt over/under voltage limits, bus voltage over/under limits, temperature limit and power limit. For an example on how to configure this pin and its registers, take a look at Example 4 in the INA2XX Arduino Library.
LEDs
The sole LED on this board is a red power LED to indicate when the board is powered.
Solder Jumpers
The board has six solder jumpers labeled SHUNT, VBUS, LED, I2C, A1 and A0. The list below outlines their functionality, default states and any notes on their use.
- SHUNT - The SHUNT jumper connects the IN± terminals to each other to allow current to flow through the on board 15mΩ resistor. The jumper is CLOSED by default. Open the jumper to disable the on board shunt resistor when using a custom shunt resistor.
- VBUS - The VBUS jumper lets users connect the VBUS and IN+ rails. The jumper is OPEN by default. Close the jumper to tie the IN+ and VBUS rails together.
- LED - The LED jumper completes the power LED circuit. This jumper is CLOSED by default. Open the jumper to disable the power LED.
- I2C - This three-way jumper pulls the INA2XX's SDA and SCL lines to 3.3V. This jumper is CLOSED by default. Completely open this jumper to disable pull-ups on the I2C bus if needed.
- A1/A0 - The A0 and A1 jumpers configure the INA2XX's I2C address. Both are CLOSED by default to set the address to 0x40. Refer to the table below or in the schematic for the available address configurations:
| A1 | A0 | Address |
|---|---|---|
| CLOSED | CLOSED | 0x40 |
| CLOSED | OPEN | 0x41 |
| OPEN | CLOSED | 0x44 |
| OPEN | OPEN | 0x45 |
Board Dimensions
The SparkFun Current Sensor - INA2XX (Qwiic) matches the standard 1" x 1" (22.5mm x 22.5mm) form factor and has four mounting holes that fit a 4-40 screw.