Littelfuse 494 Series - Manual (Page 2)

© 2013 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: 12/19/13
Surface Mount Fuses
Thin Film > 0603 Size > Fast-Acting > 494 Series
Average Time Current Curves
TIME IN SECONDS
CURRENT IN AMPERES
0.01
0.1
0.1
1
1
10
100
10 100
0.001
3.50
A
3.00
A
2.50
A
2.00
A
1.75
A
1.50
A
1.25
A
1.00
A
0.750
A
0.500
A
0.375
A
0.250
A
4.00
A
5.00
A
Temperature Rerating Curve
Reflow Condition Pb – free assembly
pre Heat
- Temperature min (T
s(min)
) 150°C
- Temperature max (T
s(max)
) 200°C
- Time (min to max) (t
s
) 60 – 180 seconds
Average Ramp-up Rate (liquidus Temp
(T
l
) to peak)
5°C/second max.
T
S(max)
to T
l
- Ramp-up Rate 5°C/second max.
Reflow
- Temperature (T
l
) (liquidus) 217°C
- Temperature (t
l
) 60 – 150 seconds
peak Temperature (T
p
) 250 +0/-5 °C
Time within 5°C of actual peak
Temperature (t
p
)
20 – 40 seconds
Ramp-down Rate 5°C/second max.
Time 25°C to peak Temperature (T
p
) 8 minutes max.
Do not exceed 260°C
Soldering Parameters
Time
Te
mperatur
e
T
P
T
L
T
S(max)
T
S(min)
25
t
P
t
L
t
S
time to peak temperature
(t 25ºC to peak)
Ramp-down
Ramp-up
Preheat
Critical Zone
T
L
to T
P