2

Table 2. Reliability Predictions

Demonstrated Performance

Ambient

Temperature

(°C)

Junction

(°C)

Performance in Time (60% Confidence)

Performance in Time (90% Confidence)

(%/1K Hours)

MTBF

Failure Rate

(%/1K Hours)

85

110

86100

1.161

34300

2.915

80

109

88800

1.126

35400

2.825

75

108

91700

1.091

36500

2.740

70

103

109100

0.917

43400

2.304

65

98

130500

0.766

52000

1.923

60

93

156900

0.637

62400

1.603

55

88

189500

0.528

75400

1.326

50

83

230200

0.434

91600

1.092

45

78

281200

0.356

111900

0.894

40

73

345400

0.290

137500

0.727

35

68

426800

0.234

169900

0.589

30

63

530800

0.188

211300

0.473

25

58

664600

0.150

264500

0.378

Notes:

[1] The 60% or 90% confidence MTBF represents the minimum level of reliability performance which is expected from 60% or 90% of all samples. The

confidence level is established based on the chi-square distribution.

[3] Data generated based on 55°C, 20mA and θJA = 780°C/W

Example of Failure Rate Calculation

Assume a device operating 8 hours/day, 5 days/week. The utilization factor, given 168hours/week is:

(8hous/day) x (5 days/week) / (168 hours/week) = 0.25

The point failure rate per year (8760 hours) at 75

°C ambient temperature is:

(1.091% / 1K hours) x 0.25 x (8760 hours/year) = 2.39% per year

Similarly, 90% confidence level failure rate per year at 75

°C:

(2.74% / 1K hours) x 0.25 x (8760 hours/year) = 6.00% per year.