INA219AIDCNR

The INA219AIDCNR from Texas Instruments is a bidirectional current and power monitor with an I2C interface that measures the voltage across a shunt resistor and the bus supply voltage, then computes current and power using an integrated math engine. The device senses bus voltages from 0V to 26V, independent of its own supply voltage (3.0V to 5.5V), making it suitable for high-side current sensing on rails up to 26V. The 12-bit ADC measures shunt voltage with programmable PGA gains (/1, /2, /4, /8) corresponding to ±320mV, ±160mV, ±80mV, and ±40mV full-scale ranges. The calibration register scales the shunt voltage reading to produce direct current values in amperes, and the internal multiplier computes power (Current × Bus Voltage / 5000). Two address pins (A0, A1) allow 16 unique I2C addresses by tying each pin to GND, VS, SDA, or SCL. The A-grade provides 1% max accuracy over temperature. The DCNR suffix denotes the SOT-23-8 package with tape-and-reel packaging.

The INA219AIDCNR measures current by sensing the voltage drop across an external shunt resistor placed between the IN+ and IN- pins. The internal differential amplifier measures this small shunt voltage (typically 0-320mV), and the PGA amplifies it by the selected gain (/1, /2, /4, /8). The 12-bit delta-sigma ADC digitizes the amplified shunt voltage. A separate ADC channel measures the bus voltage at IN- relative to GND (0 to 26V, with 4mV LSB). The conversion results are stored in the Shunt Voltage Register (01h) and Bus Voltage Register (02h). The Calibration Register (05h) is programmed with a value calculated from the desired current LSB and shunt resistance. When the calibration value is programmed, the device automatically calculates Current = Shunt_Voltage × Calibration / 4096 and stores it in the Current Register (04h). The Power Register (03h) is computed as Current × Bus_Voltage / 5000. This eliminates the need for the MCU to perform floating-point multiplication. The Configuration Register (00h) controls PGA gain, ADC resolution/averaging, and operating mode (continuous, triggered, or power-down). In triggered mode, a single conversion is performed on command; in continuous mode, the device converts continuously at the programmed rate.

INA219AIDCNR uses the VSSOP-10 (DCN, 3.0×3.0mm) surface-mount package from TI: Pin 1 = A0 (I2C address LSB), Pin 2 = A1 (I2C address MSB), Pin 3 = VIN- (shunt resistor negative), Pin 4 = VIN+ (shunt resistor positive), Pin 5 = GND, Pin 6 = SDA (I2C data), Pin 7 = SCL (I2C clock), Pin 8 = VS (supply voltage, 3-5.5V), Pin 9 = NC (no connect), Pin 10 = NC. The shunt resistor connects between VIN+ and VIN-; the bus voltage is measured at VIN-. Pins A0 and A1 set the I2C address from 0x40 to 0x4F, allowing up to 16 devices on one bus. For high-side current sensing, VIN+ connects to the supply rail and VIN- to the load. The DCN package is footprint-compatible with other VSSOP-10 current sensors.

• Battery Monitoring: High-side sensing up to 26V measures charge/discharge current and computes remaining capacity via power integration
• Server PSU: 16 I2C addresses allow monitoring 16 separate power rails from one MCU I2C bus
• Solar Power: Measures panel voltage (up to 26V) and current through shunt; power register computes output directly
• Motor Drive: Bidirectional measurement captures both drive and regenerative braking current
• Portable Devices: 6µA power-down and SOT-23-8 footprint minimize impact on space and battery life

INA219AIDCNR is a 16-bit I2C current/voltage monitor from TI in VSSOP-10. The INA226 provides similar function with separate VBUS and VSHUNT pins for bidirectional current sensing. The INA260 offers integrated 2mΩ shunt resistor in VQFN-16. The INA3221 provides 3-channel monitoring in VQFN-16. The MAX34407 from ADI/Maxim offers 4-channel power accumulator. The PAC1710 from Microchip provides unidirectional current sensing in SOT-23-6. The INA219B provides improved accuracy with 0.1% gain error.