Transientology
Thin Film > 1206 Size > Very Fast-Acting > 429 Series
Surface Mount Fuses
Introduction to Circuit Protection
Temperature Rerating Curve
Average Time Current Curves
7A
100
10
TI E I SEC O N D S
M N
1
0.
1
Note:
1. Derating depicted in this curve is in addition to the standard derating of 25% for
continuous operation.
Example:
For continuous operation at 70 degrees celsius, the fuse should be deratedas follows:
I = (0.75)(0.80)I
RAT
= (0.60)I
RAT
2. The temperature derating curve represents the nominal conditions. For questions
about temperature derating curve, please consult Littelfuse technical support
for assistance.
0.
01
0.
001
0.
1
1
10
C U R R EN T I A M PER ES
N
100
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 secs
5°C/second max
5°C/second max
217°C
60 – 150 seconds
250
+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
20 – 40 seconds
5°C/second max
8 minutes Max.
260°C
Wave Soldering
260°C, 10 seconds max.
429 Series
34
© 2009 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/429.html for current information.
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