Introduction to Circuit Protection
Introduction to Circuit Protection
Transientology
34 © 2009 Littelfuse, Inc.
Specications are subject to change without notice.
Surface Mount Fuses
429 Series
Thin Film > 1206 Size > Very Fast-Acting > 429 Series
Please refer to www.littelfuse.com/series/429.html for current information.
Average Time Current Curves
7A
TIM E IN SEC O N D S
CURRENT IN AMPERES
0.01
0.1
0.1
1
1
10
100
10 100
0.001
Reow Condition Pb – Free assembly
Pre Heat
- Temperature Min (Ts(min))150°C
- Temperature Max (Ts(max))200°C
- Time (Min to Max) (ts)60 – 180 secs
Average ramp up rate (Liquidus Temp
(TL) to peak 5°C/second max
TS(max) to TL - Ramp-up Rate 5°C/second max
Reow - Temperature (TL) (Liquidus) 217°C
- Temperature (tL)60 – 150 seconds
Peak Temperature (TP)250+0/-5 °C
Time within 5°C of actual peak
Temperature (tp)20 – 40 seconds
Ramp-down Rate 5°C/second max
Time 25°C to peak Temperature (TP)8 minutes Max.
Do not exceed 260°C
Soldering Parameters
Temperature Rerating Curve
Wave Soldering 260°C, 10 seconds max.
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)IRAT = (0.60)IR AT
2. The temperature derating curve represents the nominal conditions. For questions
about temperature derating curve, please consult Littelfuse technical support
for assistance.
Time
Temperature
TP
TL
TS(max)
TS(min)
25
tP
tL
tS
time to peak temperature
(t 25ºC to peak)
Ramp-down
Ramp-up
Preheat
Critical Zone
TL to TP