In a typical frequency inverter application, the high-side power supply for the AMC1100 (VDD1) is derived from the system supply, as shown in Figure 41. For lowest cost, a Zener diode can be used to limit the voltage to 5 V ± 10%. A 0.1-µF decoupling capacitor is recommended for filtering this power-supply path. Place this capacitor (C₁) as close as possible to the VDD1 pin for best performance. If better filtering is required, an additional 1-µF to 10-µF capacitor can be used.

Figure 41. Zener Diode Based High-Side Supply

For higher power efficiency and better performance, a buck converter can be used; an example of such an approach is based on the LM5017. A reference design including performance test results and layout documentation can be downloaded at PMP9480, Isolated Bias Supplies + Isolated Amplifier Combo for Line Voltage or Current Measurement.