Surface Mount Fuses
Introduction to Circuit Protection
Transientology
Ceramic Fuse > 440 Series
Temperature Derating Curve
Average Time Current Curves
140
100
PERCENT OF RATING
120
100
10
80
TIME IN SECONDS
60
1
40
-65
-45
-25
-5
15
35
55
75
95
115
135
155
TEMPERATURE (°C)
0.1
Note:
1. Derating depicted in this curve is in addition to the standard derating of 20% for
continuous operation.
Example:
For continuous operation at 75 degrees celsius, the fuse should be derated as follows:
I = (0.80)(0.85)I
RAT
= (0.68)I
RAT
0.01
0.001
0.1
1.0
10.0
100.0
1000.
CURRENT IN AMPERES
Soldering Parameters
reflow condition
- Temperature min (T
s(min)
)
pre Heat
- Temperature max (T
s(max)
)
- Time (min to max) (t
s
)
Average ramp-up rate (liquidus Temp
(T
l
) to peak)
T
S(max)
to T
l
- ramp-up rate
reflow
- Temperature (T
l
) (liquidus)
- Temperature (t
l
)
Pb-free assembly
150°C
60 – 180 seconds
3°C/second max.
5°C/second max.
217°C
60 – 150 seconds
260
+0/-5
T
P
T
L
Temperature
t
P
Ramp-up
Critical Zone
T
L
to T
P
200°C
T
S(max)
T
S(min)
Preheat
t
L
Ramp-down
t
S
time to peak temperature
(t 25ºC to peak)
25
Time
peak Temperature (T
p
)
Time within 5°c of actual peak
Temperature (t
p
)
ramp-down rate
Time 25°c to peak Temperature (T
p
)
Do not exceed
°C
10 – 30 seconds
6°C/second max.
8 minutes max.
260°C
Wave Soldering
260°C, 10 seconds max.
440 Series
2
© 2009 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/440.html for current information.
LITTELFUSE [ LITTELFUSE ]
