SBAS542D April 2011 – July 2015 AMC1200
In a typical frequency inverter application, the high-side power supply for the AMC1200 (VDD1) is derived from the system supply, as shown in Figure 36. For lowest cost, a Zener diode can be used to limit the voltage to 5 V ± 10%. TI recommends using a 0.1-µF, low-ESR decoupling capacitor for filtering this power-supply. TI also recommends using a 0.1-µF decoupling capacitor for filtering the power-supply on the VDD2 side. For best performance, place these capacitors (C1 and C4) as close as possible to the VDD1 and VDD2 pins respectively. If better filtering is required, an additional 1-µF to 10-µF capacitor can be used in parallel to C1 and C4.
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.