Introduction to Circuit Protection

Introduction to Circuit Protection

Transientology

© 2012 Littelfuse, Inc.

Specifications are subject to change without notice.

Surface Mount Fuses

449 Series

Please refer to www.littelfuse.com/series/449.html for current information.

Reflow Condition

Pb – Free assembly

Pre Heat

- Temperature Min (T

150°C

- Temperature Max (T

200°C

- Time (Min to Max) (t

60 – 120 secs

Average ramp up rate (Liquidus Temp

(T

3°C/second max.

T

3°C/second max.

Reflow

- Temperature (T

217°C

- Temperature (t

60 – 90 seconds

Peak Temperature (T

Time within 5°C of actual peak

Temperature (t

20 – 40 seconds

Ramp-down Rate

5°C/second max.

Time 25°C to peak Temperature (T

8 minutes max.

Do not exceed

260°C

Soldering Parameters

Average Time Current Curves

Temperature Rerating Curve

CURRENT IN AMPERES

0.01

0.1

1

10

100

1000

0

1

10

100

Note:

1. Derating depicted in this curve is in addition to the standard derating of 25% for

continuous operation.

Wave Soldering Parameters

Temperature,

3 seconds max.

Time

25

time to peak temperature

(t 25ºC to peak)

Ramp-down

Ramp-up

Preheat

Critical Zone