SFFS306 December 2021 AMC1351-Q1

3 Failure Mode Distribution (FMD)

The failure mode distribution estimation for the AMC1351-Q1 in Table 3-1 comes from the combination of common failure modes listed in standards such as IEC 61508 and ISO 26262, the ratio of sub-circuit function size and complexity, and from best engineering judgment.

The failure modes listed in this section reflect random failure events and do not include failures resulting from misuse or overstress.

Table 3-1 Die Failure Modes and Distribution

Die Failure Modes	Failure Mode Distribution (%)
Output out of specification (gain error)	20%
Output out of specification (offset error)	20%
Output out of specification (differential output at positive or negative full scale)	20%
OUTN stuck high or low	10%
OUTP stuck high or low	10%
Reduced CMTI performance	9%
Output out of specification (spikes, increased noise)	5%
Device behavior undetermined	5%
Output fail-safe function fails to indicate an error⁽¹⁾	1%

(1) Die faults that lead to a fail-safe indication of an error on the output are excluded.

The FMD in Table 3-1 excludes short-circuit faults across the isolation barrier. Faults for short circuits across the isolation barrier can be excluded according to ISO 61800-5-2:2016 if the following requirements are fulfilled:

The signal isolation component is OVC III according to IEC 61800-5-1. If a safety-separated extra low voltage (SELV) or protective extra low voltage (PELV) power supply is used, pollution degree 2 / OVC II applies. All requirements of IEC 61800-5-1:2007, 4.3.6 apply.
Measures are taken to ensure that an internal failure of the signal isolation component cannot result in excessive temperature of its insulating material.

Apply creepage and clearance requirements according to the specific equipment isolation standards of an application. Care must be taken to maintain the creepage and clearance distance of a board design to ensure that the mounting pads of the isolator on the printed-circuit board do not reduce this distance.