INA219 current sensor (CJMCU-219): specs and pinout
A zero-drift bidirectional current and power monitor chip with an I2C/SMBus interface that measures shunt voltage and bus voltage.
Specs
| Spec | Value | Source |
|---|---|---|
| Supply voltage VS | 3 V to 5.5 V | source Pin Functions (p.3) |
| Bus voltage sense range | 0 V to 26 V | source Features (p.1) |
| Shunt full-scale input (PGA settings) | +/-40 mV, +/-80 mV, +/-160 mV, +/-320 mV | source Electrical Characteristics (p.5) |
| Shunt voltage LSB | 10 uV | source Electrical Characteristics (p.5) |
| Accuracy | 0.5 % max over temperature (INA219B grade); 1 % max over temperature (INA219A grade). The grade of the chip on the module is unknown | source Features (p.1) for INA219B; Electrical Characteristics (p.5) for INA219A |
| Interface | I2C / SMBus, fast mode to 400 kHz, high-speed mode to 2.56 MHz | source Serial Bus Address (p.14) |
| Addresses | 16 selectable with A0 and A1; 1000000 with both to GND | source Table 1 (p.14) |
| Quiescent current | 0.7 mA typ, 1 mA max | source Electrical Characteristics (p.6) |
| Power-down quiescent current | 6 uA typ, 15 uA max | source Electrical Characteristics (p.6) |
| Operating temperature | Specified at TA -25 degC to 85 degC | source Electrical Characteristics header condition (p.5) |
Power
| Value | Source | |
|---|---|---|
| Supply | VS 3 V to 5.5 V | source Electrical Characteristics (p.6) |
| Current | 0.7 mA typ, 1 mA max (active) | source Electrical Characteristics (p.6) |
Chip pins
These are the pins of the chip on the module, from the chip datasheet. The module's own header may label or expose them differently.
These are the pin numbers of the bare INA219 chip (SOIC), not the CJMCU-219 header: do not wire the module from this table. The pin table is the bare INA219 chip (SOIC numbers). The CJMCU-219 module (shunt resistor value, header order, I2C pull-ups, address jumpers) is not covered by an official document.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| IN+ | Positive differential shunt voltage; connect to the positive side of the shunt resistor | Analog input | SOIC pin 8 | source Pin Functions (p.3) |
| IN- | Negative differential shunt voltage; bus voltage is measured from this pin to ground | Analog input | SOIC pin 7 | source Pin Functions (p.3) |
| GND | Ground | SOIC pin 6 | source Pin Functions (p.3) | |
| VS | Power supply | 3-5.5 V | SOIC pin 5 | source Pin Functions (p.3) |
| SCL | Serial bus clock line | SOIC pin 4 | source Pin Functions (p.3) | |
| SDA | Serial bus data line | SOIC pin 3 | source Pin Functions (p.3) | |
| A0 | Address pin | SOIC pin 2 | source Pin Functions (p.3); Table 1 (p.14) | |
| A1 | Address pin | SOIC pin 1 | source Pin Functions (p.3); Table 1 (p.14) |
Build with it
Project ideas for the INA219 current sensor (CJMCU-219). Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- Battery current monitor: A single cell at 3.7 V sits inside the 0-26 V bus range (IN+ and IN- must stay at or below 26 V). Use a protected cell (the protection of the stocked cell is not stated), and measure through the shunt at low current only until the module shunt value is known, because its continuous current limit is not documented. Do not short the cell.
- Pump current graph: The pump runs from its own 5 V supply through the shunt; the ESP32 only reads I2C at 3.3 V (VS is 3-5.5 V).
- Uno power meter with LCD: Uno 5 V is within the 3-5.5 V supply; keep the load below the module's shunt rating, which is not documented here.
Common mistakes
- Exceeding the sense range: the bus input reads 0 to 26 V and shunt full scale tops out at +/-320 mV (source)
- Wrong address: A0 and A1 each tie to GND, VS, SDA or SCL, giving 16 addresses; both at GND is 1000000 (source)
- Forgetting calibration: the current register is the shunt voltage times the Calibration register divided by 4096, so it reads zero until that is written (source)
Not covered by the official source
- CJMCU-219 module board is not documented; the shunt resistor value and so the current range are unknown.
- Check quiescent and power-down current figures against the datasheet table.
- Temperature -25 to 85 degC is the TA condition on the Electrical Characteristics table (p.5), not a Recommended Operating Conditions row.
- The accuracy grade (INA219A or INA219B) of the chip on the CJMCU-219 module is not documented.
Sources
- link (TI INA219 datasheet SBOS448G, Aug 2008, revised Dec 2015)