SBASAO0A May 2023 – September 2023 AMC130M03
PRODUCTION DATA
Figure 9-5 illustrates phase A of a three-phase energy meter. The other AMC130M03 devices that monitor phases B and C are connected in a similar way. The phase A current, ISHUNT, is sensed with a shunt resistor (RSHUNT) using channel 0 of the ADC (AIN0N, AIN0P). One terminal of the shunt becomes the isolated ground ISO_GND of the circuit and is connected to the ground pin HGND (pin 5) of the isolated side of the AMC130M03. The phase A to neutral voltage VPHASEA is sensed with a resistor divider connected to channel 1, and the AIN12N pin is also connected to the ISO_GND node. The high side of the resistor divider is connected to the neutral line, the mid-point of the resistor divider is connected to the positive ADC input AIN1P, and the low side of the resistor divider (which is sensing the ISO_GND node) is connected to the negative input AIN12N of channel 1; therefore, the negative phase voltage is measured at channel 1. Thus, voltages measured by channel 1 of the AMC130M03 are opposite in sign to the phase voltage VPHASEA and the phase current ISHUNT, which is a classic approach in single-phase and poly-phase metering.
The selection of the shunt resistor value is made based on the manufacturer and current range required for energy measurements. The voltage divider resistors for the voltage channel are selected to make sure the mains voltage is divided down to adhere to the normal input voltage ranges of the AMC130M03.
In this design, the AMC130M03 interacts with an MCU in the following manner: