ISO7421: Reliability after ESD event

Hi Franz,

Thanks for reaching out., please find my inputs below.

Franz Schellhase said:

Can you, as the manufacturer, make a statement on the part of TI as to what extent the high-voltage strength of the ISO7421D / ISO7420D component may be limited if the component is no longer functional as a result of an ESD event?

Assuming the ESD event is applied across the isolation barrier and the ESD voltage level applied exceeds device capability, the damage caused by the ESD event is going to be uncontrolled and the amount of damage cannot be estimated. Due to this, the isolation barrier will be compromised and high voltage strength cannot be estimated.

Franz Schellhase said:

Do you know whether the tests for obtaining the Safety and Regulatory Approvals can still be passed?

Since the isolation barrier is damaged, I do not believe the device will be able to meet the isolation tests for obtaining the Safety and Regulatory Approvals.

Franz Schellhase said:

Can a statement be made as to whether the energy of an ESD pulse is sufficient to damage the insulation barrier?

Yes, we do know the ESD withstanding capabilities of our isolation devices. ISO7421 is one of our older isolator devices with not so much ESD withstanding capability. The newer device families, like the ISO77xx, support support much greater than 8kV of ESD across the isolation barrier. We recommend customers to use our newer isolation devices that support much superior overall performance. Thanks.

Regards,
Koteshwar Rao