ISOM8110: Photocopier Emulator: Effects of Excessive Stress on Internal Components

DDdoor

Part Number: ISOM8110

Hello,

If excessive stress is applied to the photocopier emulator, resulting in device failure, would its internals be open or shorted?

Best regards,
DDdoor

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 317280 points

I'd guess that it is more likely that damage would break the connection, i.e., the output would be open.

But it is possible that a high current continues to flow through the input. There is no guarantee.

0 Andrew J over 1 year ago in reply to Clemens Ladisch

TI__Mastermind 29415 points

Hello DDoor,

Failure modes in normal devices cannot be guaranteed, as Clemens suggested.

However, isolations devices will fail-open provided certain conditions are accounted for when designing. The following document outlines the behavior of the isolation barrier pre and post a single side failure event.

Understanding failure modes in isolators (Rev. B) (ti.com).

Best,
Andrew

0 DDdoor over 1 year ago in reply to Andrew J

Expert 2435 points

Hello,
Thank you for your reply.

Based on the documentation (slyy081b), it seems that TI's isolators, which utilize series-capacitor isolation, are always perceived to potentially fail open.
What do you mean by the specific conditions you mentioned?

Best regards,
DDdoor

+1 Andrew J over 1 year ago in reply to DDdoor

TI__Mastermind 29415 points

Hello DDoor,

TI's isolators will fail-open assuming the maximum junction temperature (150decC) is not exceeded. Exceeding the maximum temperature can cause the remaining die to fail as a result of the die heating-up. The safety limiting values specify the limits in which the isolation barrier is preserved, even under fault conditions.

In the datasheet, the safety limiting current values refer to the total current through any combination of pins (including the supply and I/O pins) that the device can withstand before damage to the isolation barrier occurs. Similarly, the safety limiting power values given by the datasheet refers to the maximum total power that the device can withstand before damage to the isolation barrier occurs.

Documentation on safety limiting values are linked below for more information:

Isolation

Isolation forum

ISOM8110: Photocopier Emulator: Effects of Excessive Stress on Internal Components