(Regulating Pulse Width Modulator) is not always included in the standard Proteus component library by default. To use it for your simulation projects, you must either download a third-party library or use a compatible equivalent. ariat-tech.com 1. Where to Find the SG3524 Proteus Library
Many GitHub users have contributed to Proteus libraries. The SG3524 is often included in generic "PWM IC" libraries.