9.3.1 Electromagnetic Compatibility (EMC) Considerations

The ISOW7821 device uses emissions reduction schemes for the internal oscillator and advanced internal layout scheme to minimize radiated emissions at the system level.

Many applications in harsh industrial environment are sensitive to disturbances such as electrostatic discharge (ESD), electrical fast transient (EFT), surge and electromagnetic emissions. These electromagnetic disturbances are regulated by international standards such as IEC 61000-4-x and CISPR 22. Although system-level performance and reliability depends, to a large extent, on the application board design and layout, the ISOW7821 device incorporates many chip-level design improvements for overall system robustness. Some of these improvements include:

• Robust ESD protection cells for input and output signal pins and inter-chip bond pads.
• Low-resistance connectivity of ESD cells to supply and ground pins.
• Enhanced performance of high voltage isolation capacitor for better tolerance of ESD, EFT and surge events.
• Bigger on-chip decoupling capacitors to bypass undesirable high energy signals through a low impedance path.
• PMOS and NMOS devices isolated from each other by using guard rings to avoid triggering of parasitic SCRs.
• Reduced common mode currents across the isolation barrier by ensuring purely differential internal operation.