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AS8002

Data Sheet - D e t a i l e d D e s c r i p t i o n

7 Detailed Description

Figure 3 presents a typical application schematic for the AS8002 used for voltage and current measurement of a device connected to the grid

such a solar inverter or microinverter.

The external circuitry comprises the power supply unit that is connected to the grid signal and that generates a stable DC voltage which is the

supply of the AS8002 and the digital isolation. Both current and voltage are scaled down and filtered prior to be sensed by the AS8002. In the

case of the voltage, a resistor divider is enough to scale down the voltage. In the case of the current, a low ohmic shunt resistor should be used.

The value of this shunt resistor should be calculated in order not to saturate the inputs of the AS8002 but to provide a good signal to noise ratio.

It is also important to minimize the value of the shunt resistor to lower the losses and increase the overall efficiency.

Unlike commonly used sensing methods, the AS8002 is connected to the same potential level as the grid, which allows using a low cost shunt

resistor as the sensing device. The isolation is achieved by means of a digital isolator which should be able to handle a data rate of up to 2Mbps.

This sensing solution has several advantages compared to other common solutions, like the stability over temperature, accuracy of the

measurements and allowed bandwidth. All these lead to an accurate control of the DC-AC converter with low DC injection currents.

Figure 3. Typical Application Circuit