SFFS594A December   2023  – November 2024 TPSI3100 , TPSI3100-Q1

 

  1.   1
  2.   Trademarks
  3. 1Overview
  4. 2Functional Safety Failure In Time (FIT) Rates
  5. 3Failure Mode Distribution (FMD)
  6. 4Pin Failure Mode Analysis (Pin FMA)
  7. 5Revision History

3 Failure Mode Distribution (FMD)

The failure mode distribution for the TPSI310x-Q1, TPSI311x-Q1, TPSI312x-Q1, and TPSI3133-Q1 family and the TPSI310x, TPSI311x, TPSI312x, and TPSI3133 family in Table 4-2 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 ModesFailure Mode Distribution (%)
VDDH/VDDM rails fail to power up, VDRV remains low10
VDRV does not respond to EN signaling12
Output power not meeting specification
Longer VDDH/VDDM start-up and recovery times		20
VDDH not regulated, potential device damage14
VDRV propagation times longer than specified2
Higher EMI4
Unpredictable power-down sequence2
Fault and alarm events incorrectly reported13
Incorrect comparator behavior 11
VDRV fails to turn off within reference accuracy range 4
VDRV output held high 8

The FMD in Die Failure Modes and Distribution excludes short circuit faults across the isolation barrier. Faults for short circuit across the isolation barrier can be excluded according to ISO 61800-5-2:2016 if the following requirements are fulfilled:

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

Creepage and clearance requirements should be applied according to the specific equipment isolation standards of an application. Care should 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.