This user’s guide compares the features of the INA219 and INA232 digital power monitors, and outlines key differences that need to be considered when migrating from INA219 to INA232. A design example is used to highlight both commonalities and differences between the two. The example demonstrates that there are a range of applications that can be served by both devices, either to solve a supply chain constraint issue or simply to upgrade to the latest product offerings from TI. For applications that require features unique to one device, substituting one device with the other device is not always possible.
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A digital power monitor is specially designed for current sensing applications, with an integrated analog-to-digital converter that is able to withstand common-mode voltages that are much higher than the device power supply itself. As a result, the digital power monitor can be directly interfaced with the circuit being measured.
Digital power monitors extract the small differential shunt voltage from a normally high common-mode voltage rail. This shunt voltage is proportional to the load current supplied by the voltage rail. The common mode (Bus) voltage is also measured. With these two measurements, the power monitors calculate the current, voltage, and power. These quantities are available as bit streams and available through the digital interface. Figure 1-1 shows a block diagram of a typical power monitor with I2C digital interface.
The INA219 is a current shunt and power monitor with an I2C- or SMBus-compatible interface. The device monitors both shunt voltage drop and bus supply voltage, with programmable conversion times and filtering. A programmable calibration value, combined with an internal multiplier, enables direct readouts of current in amperes. An additional multiplying register calculates power in watts. The I2C- or SMBus-compatible interface features 16 programmable addresses. The INA219 is available in two grades: A and B. The B grade version has higher accuracy and higher precision specifications.
The INA232 device is a 16-bit digital current monitor with an I2C- or SMBus-compatible interface that is compliant with a wide range of voltages such as 1.2 V, 1.8 V, 3.3 V, and 5.0 V. The device monitors the voltage across an external sense resistor and reports values for current, bus voltage, and power. The INA232 senses current on common-mode bus voltages that can vary from –0.3 V to 48 V, independent of the supply voltage. The device operates from a single 1.7-V to 5.5-V supply, drawing a typical supply current of 300 μA in normal operation. The device can be placed in a low-power standby mode where the typical operating current is 2.2 μA.
Figure 1-2 compares some of the key electrical specifications of INA219 and INA232