In a typical frequency-inverter application, the high-side power supply (AVDD) for the device is directly derived from the floating power supply of the upper gate driver. For lowest system-level cost, a Zener diode can be used to limit the voltage to 5 V or 3.3 V (±10%). Alternatively a low-cost low-drop regulator (LDO), for example the LM317-N, can be used to adjust the supply voltage level and minimize noise on the power supply node. A low-ESR decoupling capacitor of 0.1 µF is recommended for filtering this power-supply path. Place this capacitor (C2 in Figure 57) as close as possible to the AVDD pin of the AMC1303 for best performance. Further, an additional capacitor with a value in the range of 2.2 µF to 10 µF is recommended.
The floating ground reference (AGND) is derived from the end of the shunt resistor, which is connected to the negative input (AINN) of the device. If a four-pin shunt is used, the device inputs are connected to the inner leads and AGND is connected to one of the outer leads of the shunt.
For decoupling of the digital power supply on the controller side, TI recommends using a 0.1-µF capacitor assembled as close to the DVDD pin of the AMC1303 as possible, followed by an additional capacitor in the range of 2.2 µF to 10 µF.