Isolated ΔΣ modulators are widely used for voltage measurements in high-voltage applications that must be isolated from a low-voltage domain. Typical applications are AC line voltage measurements, either line-to-neutral or line-to-line, and DC-link voltage measurements in frequency inverters. The AMC3336 integrates an isolated power supply for the high-voltage side and therefore makes the device particularly easy to use in applications that do not have a high-side supply readily available or where a high-side supply is referenced to a different ground potential than the signal to be measured.

Figure 8-1 shows a simplified schematic of the AMC3336 in a solar inverter where the AC phase voltage is measured on the grid-side. At that location in the system there is no supply readily available for powering the isolated amplifier. The integrated isolated power-supply, together with its bipolar input voltage range, makes the AMC3336 ideally suited for AC line-voltage sensing. In this example, phase current is sensed by the AMC3306M05 across a shunt resistor on the grid-side of an LCL filter where there is also no suitable supply available for powering the isolated amplifier. The integrated power-supply of the AMC3306M05 eliminates this problem and enables current sensing at locations that are optimal for the system.