These safety application notes provide information about a component's safety factor (SF), such as failure rate, failure mode distribution (FMD), and pin failure mode and effects analysis (FMEA). These notes also provide system integrators with access to important information to assist them in designing safety-related systems. Therefore, this first part of the series discusses the recommended validation checks that system integrators should perform before using a component's safety application note.
Introduction
The Analog Devices “Know Your Safety” Application Notes series (1, 2, 3) provides an overview of safety application notes for ADI Functional Safety (FS) integrated circuits (ICs): non-FS compliant devices or standard products recommended for FS applications due to their functions, features, and extensive user experience. As shown in Figure 1, ADI safety application notes detail a component's development process, its failure rate prediction calculated from three reliability prediction methods, the failure mode distribution (FMD) in terms of the IC's system functions, and its pin failure mode and effects analysis (FMEA), which covers short-circuit failures to power, ground, adjacent pins, and open pins.
This second series of articles on ADI security application notes aims to guide system integrators in using these notes to facilitate their technical security analyses. Furthermore, this first part focuses on the next step system integrators should take when using a security application note for their ADI component.
Verification of the Conditions Used for Reliability Predictions:
ADI's Safety Application Notes provide reliability predictions based on three methods: the failure rate calculated using SN29500, IEC 62380, and the Arrhenius equation, using high-temperature operating life (HTOL) data. For each reliability prediction method shown in Figure 2, there are notes below the tables summarizing the calculated failure rate and the conditions used. This includes information such as the mission profile, operating voltage, power dissipation, thermal specifications based on the package used, the confidence level in the case of the Arrhenius HTOL, and other input data required for the reliability prediction method, which can be derived from the product data sheet, as well as design-related data such as integration density, technology structure, etc. This information is made available so that system integrators familiar with reliability predictions can recalculate the failure rates of an integrated circuit as needed when the operating conditions assumed in the initial calculations differ. Part 1 of the "Know Your Safety" Safety Application Notes indicates where the ADI reliability database can be found and provides information on how to modify the confidence level of a reliability prediction. If similar conditions are used and the assumed conditions are directly applicable, system integrators can easily use the reliability prediction data from the safety application note.
Figure 1. LTC2933 Security Application Note.
Figure 2. Information on the failure rate of the LTC2933.
Checking the Conditions Used for FMD:
In addition to the system function, the FMD section of an ADI Safety Application Note also shows the intended application circuit. This is shown in Figure 3. It is important for system integrators to check whether the integrated circuit used in their application matches the intended application circuit. Otherwise, some modifications to the analysis may be necessary. For example, if we look at Figure 3, perhaps only four of the six channels of the LTC2933.
Figure 3. FMD information for LTC2933.
Verifying the Conditions Used for Pin FMEA:
The pin FMEA section of a safety application note, as shown in Figure 4, displays the component package used, the assumed device configuration, and the actual device configuration, along with tables showing the analysis. System integrators should ensure that a pin layout and device configuration similar to those of the assumed application circuit are used so that they can utilize this analysis in their design.
Figure 4. FMEA analysis information for the LTC2933 pins.
In some cases, there may be additional diagnostics or other system-level security measures that ADI's analysis did not consider.
Post-consistency check activities:
After performing a series of validity checks on the security application note, system integrators may conclude that the information is readily applicable to their application or that some modifications are necessary. If the latter occurs, they can contact ADI through ADI's support channels.
conclusion
, ADI's Safety Application Notes for FS-enabled integrated circuits are a critical resource for system integrators, providing detailed reliability and failure analysis data necessary to facilitate FS design. However, the effectiveness of these documents depends on a rigorous verification process, in which integrators must check that the mission profiles, application circuits, and pin configurations assumed in the notes match their specific system requirements. By confirming these conditions—or contacting ADI for further technical assistance when discrepancies arise—engineers can help ensure that the failure rates and FMD data they incorporate into their safety analysis are accurate and robust, ultimately leading to more reliable safety-related industrial systems.
References
1 Bryan Borres. “Know Your Safety Application Notes — Part 1: Failure Rates.” Analog Devices, Inc., August 2025.
2 Bryan Borres. “Know Your Safety Application Notes — Part 2: Failure Mode Distribution.” Analog Dialogue, vol. 59, October 2025.
3 Bryan Borres. “Safety Application Notes: Part 3: Pin FMEA.” Analog Devices, Inc., November 2025.
Author: Bryan Angelo Borres, Senior Functional Safety Engineer at Analog Devices
About the author:
Bryan Angelo Borres is a TÜV-certified functional safety engineer specializing in industrial functional safety. As a senior power applications engineer, he helps component designers and system integrators design functionally safe power products that meet industrial functional safety standards, such as IEC 61508. Bryan is a member of the IEC Philippine National Committee for IEC TC65/SC65A and the IEEE Functional Safety Standards Committee. He also holds a postgraduate diploma in power electronics and has over seven years of extensive experience designing efficient and robust power electronics systems.
