Surface Mount Fuses
Ceramic Fuse > 438 Series
438 Series – 0603 Fast-Acting Fuse
Description
The 438 Series is a 100% Lead-free, RoHS compliant and
Halogen-free fuse series designed specifically to provide
over-current protection to circuits that operate under high
working ambient temperature up to 150ºC.
The general design ensures excellent temperature stability
and performance reliability.
The high I²t values which is typical in the Littelfuse Ceramic
Fuse family ensure high inrush current withstand capability.
Agency Approvals
AGENCY
AGENCY FILE NUMBER
E10480
LR29862
AMPERE RANGE
0.250A – 6A
0.250A – 6A
Features
from -55ºC to +150ºC
compliant and Halogen-
free
Applications
and lead-free reflow /
wave soldering
Electrical Characteristics for Series
% of Ampere
Rating
100%
250%
Ampere Rating
0.250A – 6A
0.250A – 6A
Opening Time at 25ºC
4 Hours, Minimum
5 Seconds, Maximum
Electrical Specifications by Item
Ampere
Max.
Amp
Rating
Voltage
Code
(A)
Rating (V)
0.25
0.375
0.5
0.75
1
1.25
1.5
1.75
2
2.5
3
3.5
4
5
6
Notes:
1. AC Interrupting Rating tested at rated voltage with unity power factor. DC Interrupting
Rating tested at rated voltage with time constant < 0.8 msec.
2. Nominal Resistance measured with < 10% rated current.
3. Nominal Melting I²t measured at 1 msec. opening time.
4. Nominal Voltage Drop measured at rated current after temperature has stabilized.
Devices designed to carry rated current for 4 hours minimum. It is recommended that
devices be operated continuously at no more than 80% rated current. See “Temperature
Rerating Curve”for additional rerating information.
Devices designed to be mounted with marking code facing up.
Interrupting Rating
Nominal Nominal Voltage Nominal Power Agency Approvals
Nominal
Drop At Rated
Dissipation At
Resistance Melting I
2
t
(A
2
Sec.)
3
Current (V)
4
Rated Current (W)
(Ohms)
2
2.024
1.247
0.829
0.466
0.310
0.200
0.174
0.125
0.051
0.0324
0.0252
0.0203
0.0169
0.0113
0.0087
0.0017
0.0041
0.0100
0.0281
0.0593
0.0510
0.0902
0.1440
0.1490
0.1977
0.2922
0.4752
0.6920
0.7398
1.3838
0.550
0.488
0.486
0.378
0.351
0.365
0.368
0.360
0.107
0.095
0.093
0.082
0.079
0.074
0.072
0.138
0.183
0.243
0.284
0.351
0.456
0.552
0.540
0.214
0.238
0.279
0.287
0.316
0.370
0.432
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
.250
.375
.500
.750
001.
1.25
01.5
1.75
002.
02.5
003.
03.5
004.
005.
006.
32
32
32
32
32
32
32
32
32
32
32
32
32
32
24
50 A @ 32 VDC
50 A @ 24 VDC
© 2009 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/438.html for current information.
21
Revised: August 21, 2009
438 Series
Surface Mount Fuses
Introduction to Circuit Protection
Transientology
Ceramic Fuse > 438 Series
Temperature Rerating Curve
Average Time Current Curves
.250A
.375A
.500A
.750A
1A
1.25A
1.5A
1.75A
2A
2.5A
3A
3.5A
4A
5A
6A
140
100
PERCENT OF RATING
120
10
100
80
TIME IN SECONDS
1
60
40
-65
-45
-25
-5
15
35
55
75
95
115
135
155
TEMPERATURE (°C)
0.1
Note:
1. Rerating depicted in this curve is in addition to the standard rerating of 20% for
continuous operation.
0.01
For continuous operation at 75 degrees celsius, the fuse should be rerated as follows:
I = (0.80)(0.85)I
RAT
= (0.68)I
RAT
0.001
0.1
1
10
100
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
)
150°C
60 – 180 seconds
3°C/second max.
5°C/second max.
217°C
60 – 150 seconds
260
+0/-5
T
P
Ramp-up
t
P
Critical Zone
T
L
to T
P
Temperature
200°C
T
L
T
S(max)
Preheat
t
L
Ramp-down
T
S(min)
t
S
25
time to peak temperature
(t 25ºC to peak)
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.
438 Series
22
© 2009 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/438.html for current information.
Surface Mount Fuses
Ceramic Fuse > 438 Series
Product Characteristics
Body:
Advanced Ceramic
Terminations:
Ag / Ni / Sn (100% Lead-free)
Element Cover Coating:
Lead-free Glass
Moisture Resistance
Thermal Shock
Mechanical Shock
Vibration
Vibration,
High Frequency
Dissolution of
Metallization
Terminal Strength
MIL
-STD-202, Method 106G
MIL
-STD-202, Method 107G,
Materials
Moisture
Sensitivity Level
Solderability
Humidity
ESD Immunity
Resistance to
Solder Heat
Condition A
MIL
-STD-202, Method 201A
MIL
-STD-202, Method 204D,
Condition D
Condition D
Dimensions
Part Marking System
Amp Code
Marking Code
D
E
F
G
H
J
K
L
N
O
P
R
S
T
U
0.530 +/- 0.150
[0.021 +/- 0.006]
1.54 ± 0.150
[0.061 ± 0.006]
.250
.375
.500
.750
001.
1.25
01.5
0.85 ± 0.150
[0.033 ± 0.006]
0.502 ± 0.080
[0.020 ± 0.003]
1.75
002.
02.5
003.
03.5
004.
005.
0.432 +/- 0.150
[0.017 +/- 0.006]
006.
0.74
[0.029]
0.60
[0.024]
Part Numbering System
0438 005. W R
1.00
[0.039]
SERIES
PACKING CODE
1.94
[0.076]
AMP CODE
QUANTITY CODE
W = 3000 pcs
Packaging
Packaging Option
8mm Tape and Reel
Packaging Specification
Quantity
3000
Quantity &
Packaging Code
WR
© 2009 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/438.html for current information.
23
438 Series
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