The INA239-Q1 operates off a 2.7 V to 5.5 V supply but can measure voltage and current on rails as high as 85 V. The current is measured by sensing the voltage drop across a external shunt resistor at the IN+ and IN– pins. The input stage of the INA239-Q1 is designed such that the input common-mode voltage can be higher than the device supply voltage, V_S. The supported common-mode voltage range at the input pins is –0.3 V to +85 V, which makes the device well suited for both high-side and low-side current measurements. There are no special considerations for power-supply sequencing because the common-mode input range and device supply voltage are independent of each other; therefore, the bus voltage can be present with the supply voltage off, and vice-versa without damaging the device.

The device also measures the bus supply voltage through the V_BUS pin and temperature through the integrated temperature sensor. The differential shunt voltage is measured between the IN+ and IN– pins, while the bus voltage is measured with respect to device ground. Monitored bus voltages can range from 0 V to 85 V, while monitored temperatures can range from -40 ºC to +125 ºC.

Shunt voltage, bus voltage, and temperature measurements are multiplexed internally to a single ADC as shown in Figure 7-1.

Figure 7-1 High-Voltage Input Multiplexer