DRV8889-Q1, DRV8889A-Q1 Functional Safety FIT Rate, FMD and Pin FMA

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1 Overview

This document contains information for DRV8889-Q1 and DRV8889A-Q1 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 their distribution (FMD) based on the primary function of the device
Pin failure mode analysis (Pin FMA)

DRV8889-Q1 and DRV8889A-Q1 were developed using a quality-managed development process, but were not developed in accordance with the IEC 61508 or ISO 26262 standards.

Figure 1-1 shows the functional block diagram for the DRV8889-Q1 and DRV8889A-Q1 as a reference.

Figure 1-1 DRV8889/A-Q1 Block Diagram

2 Functional Safety Failure In Time (FIT) Rates

This section provides Functional Safety Failure In Time (FIT) rates for DRV8889-Q1 and DRV8889A-Q1 based on two different industry-wide used reliability standards:

Table 2-1 provides FIT rates based on IEC TR 62380 / ISO 26262 part 11 for the HTSSOP Package.
Table 2-2 provides FIT rates based on IEC TR 62380 / ISO 26262 part 11 for the QFN Package.
Table 2-3 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 for HTSSOP Package

FIT IEC TR 62380 / ISO 26262	FIT (Failures Per 10⁹ Hours)
Total Component FIT Rate	23
Die FIT Rate	7
Package FIT Rate	16

Table 2-2 Component Failure Rates per IEC TR 62380 / ISO 26262 Part 11 for QFN Package

FIT IEC TR 62380 / ISO 26262	FIT (Failures Per 10⁹ Hours)
Total Component FIT Rate	21
Die FIT Rate	9
Package FIT Rate	12

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

Mission Profile: Motor Control from Table 11
Power dissipation: 1 W
Climate type: World-wide Table 8
Package factor (lambda 3): Table 17b
Substrate Material: FR4
EOS FIT rate assumed: 0 FIT

Table 2-3 Component Failure Rates per Siemens Norm SN 29500-2

Table	Category	Lambda ref FIT	Theta vj
5	CMOS/BICMOS ASICs Analog & Mixed =<50V supply	60 FIT	70°C

The Reference FIT Rate and Reference Virtual T_J (junction temperature) in Table 2-3 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 DRV8889-Q1 and DRV8889A-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 due to misuse or overstress.

Table 3-1 Die Failure Modes and Distribution

Die Failure Modes	Failure Mode Distribution (%)
xOUTx is stuck LOW when commanded OFF	8%
xOUTx is stuck OFF when commanded LOW	12%
xOUTx ON resistance too high when commanded LOW	8%
Low side slew rate too fast or too slow	3%
xOUTx is stuck HIGH when commanded OFF	9%
xOUTx is stuck OFF when commanded HIGH	13%
xOUTx ON resistance too high when commanded HIGH	9%
High side slew rate too fast or too slow	3%
Dead time is too short	4%
Incorrect communication or fault indication	14%
Current regulation incorrect	17%