UCC2808A-xQ1
Functional Safety FIT Rate, FMD and Pin FMA

1 Overview

This document contains information for UCC2808A-xQ1 (UCC2808A-1Q1 and UCC2808A-2Q1 in SOIC 8 package) to aid in a functional safety system design. Information provided are:

Functional safety failure in time (FIT) rates of the semiconductor component estimated by the application of industry reliability standards
Component failure modes and distribution (FMD) based on the primary function of the device
Pin failure mode analysis (pin FMA)

Figure 1-1 shows the device functional block diagram for reference.

UCC2808A-2Q1 UCC2808A-1Q1 Functional Block Diagram

Figure 1-1 Functional Block Diagram

UCC2808A-xQ1 were developed using a quality-managed development process, but were not developed in accordance with the IEC 61508 or ISO 26262 standards.

2 Functional Safety Failure In Time (FIT) Rates

This section provides functional safety failure in time (FIT) rates for UCC2808A-xQ1 based on two different industry-wide used reliability standards:

Table 2-1 provides FIT rates based on IEC TR 62380 / ISO 26262 part 11
Table 2-2 provides FIT rates based on the Siemens Norm SN 29500-2

Table 2-1 Component Failure Rates per IEC TR 62380 / ISO 26262 Part 11

FIT IEC TR 62380 / ISO 26262	Power Dissipation (mW)	FIT (Failures Per 10⁹ Hours)
Total component FIT rate	75	10
	150	11
	300	15
Die FIT rate	75	3
	150	4
	300	7
Package FIT rate	75	7
	150	7
	300	8

The failure rate and mission profile information in Table 2-1 comes from the reliability data handbook IEC TR 62380 / ISO 26262 part 11:

Mission profile: Motor control from table 11 or figure 16
Power dissipation: 75mW, 150mW, 300mW
Climate type: World-wide table 8 or figure 13
Package factor (lambda 3): Table 17b or figure 15
Substrate material: FR4
EOS FIT rate assumed: 0 FIT

Table 2-2 Component Failure Rates per Siemens Norm SN 29500-2

Table	Category	Reference FIT Rate	Reference Virtual T_J
5	CMOS, BICMOS Digital, analog, or mixed	25 FIT	55°C

The reference FIT rate and reference virtual T_J (junction temperature) in Table 2-2 come from the Siemens Norm SN 29500-2 tables 1 through 5. Failure rates under operating conditions are calculated from the reference failure rate and virtual junction temperature using conversion information in SN 29500-2 section 4.

3 Failure Mode Distribution (FMD)

The failure mode distribution estimation for UCC2808A-xQ1 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 (%)
OUTA and OUTB stuck low	15
OUTA and OUTB pulse width not as expected	17
OUTA stuck low	9.5
OUTA stuck high	9.5
OUTB stuck low	9.5
OUTB stuck high	9.5
System is unstable	7
No effect	23