In a typical application, the high-side power supply (VDD1) for the ISO224 is generated from the low-side supply (VDD2) of the device by an isolated DC/DC converter circuit. A low-cost solution is based on the push-pull driver SN6501 and a transformer that supports the desired isolation voltage ratings. TI recommends using a low-ESR decoupling capacitor of 0.1 µF and an additional capacitor of a minimum 1 µF for both supplies of the ISO224. Figure 51 shows the recommended placement of these decoupling capacitors as close as possible to the ISO224 power-supply pins to minimize supply current loops and electromagnetic emissions.

To decouple the output of the integrated LDO, use a 0.22-µF capacitor placed as close to the VCAP pin of the ISO224 as possible.

The ISO224 does not require any specific power up sequencing. Consider the analog settling time t_AS as specified in the Switching Characteristics table after ramp up of the VDD1 high-side supply.

Figure 51. SN6501-Based, High-Side Power Supply