Introduction to Circuit Protection

Introduction to Circuit Protection

Transientology

© 2009 Littelfuse, Inc.

Specifications are subject to change without notice.

Surface Mount Fuses

Please refer to www.littelfuse.com/series/440.html for current information.

440 Series

Ceramic Fuse > 440 Series

Average Time Current Curves

0.001

0.01

0.1

1

10

1

10

100

1000

CURRENT IN AMPERES

Reflow Condition

Pre Heat

-Temperature Min (T

150°C

-Temperature Max (T

200°C

-Time (Min to Max) (t

60 – 180 seconds

Average Ramp-Up Rate (LiquidusTemp

(T

3°C/second max.

T

5°C/second max.

Reflow

-Temperature (T

217°C

-Temperature (t

60 – 150 seconds

PeakTemperature (T

Time within 5°C of actual peak

Temperature (t

10 – 30 seconds

Ramp-down Rate

6°C/second max.

Time 25°C to peakTemperature (T

8 minutes max.

Do not exceed

260°C

Soldering Parameters

Temperature Derating Curve

40

60

80

100

120

140

-65

-45

-25

-5

15

35

55

75

95

115

135

155

TEMPERATURE (°C)

Time

25

time to peak temperature

(t 25ºC to peak)

Ramp-down

Ramp-up

Preheat

Critical Zone

For continuous operation at 75 degrees celsius, the fuse should be derated as follows:

I = (0.80)(0.85)I

Note:

1. Derating depicted in this curve is in addition to the standard derating of 20% for

continuous operation.

Wave Soldering

260°C, 10 seconds max.