
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.
Features
Agency Approvals
AGENCY AGENCY FILE NUMBER AMPERE RANGE
E10480 0.250A – 6A
LR29862 0.250A – 6A
Electrical Characteristics for Series
% of Ampere
Rating
100% 0.250A – 6A 4 Hours, Minimum
250% 0.250A – 6A 5 Seconds, Maximum
Ampere Rating Opening Time at 25ºC
• OperatingTemperature
from -55ºC to +150ºC
• 100%Lead-free,RoHS
compliant and Halogenfree
Applications
• HandheldElectronics
• LCDDisplays
• BatteryPacks
Additional Information
Datasheet
• Suitableforbothleaded
and lead-free reflow /
wave soldering
• HardDiskDrives
• SDMemoryCards
Resources
Samples
Electrical Specifications by Item
Ampere
Rating
0.375 .375 63VDC 1.247 0.0041 0.488 0.183 x x
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.
© 2013 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: 12/19/13
Amp
Code
(A)
0.25 .250 63VDC
0.5 .500 63VDC 0.829 0.0100 0.486 0.243 x x
0.75 .750 63VDC 0.466 0.0281 0.378 0.284 x x
1 0 01. 63VDC 0.310 0.0593 0.351 0.351 x x
1.25 1.25 63VDC 0.200 0.0510 0.365 0.456 x x
1. 5 01.5 63VDC 0.174 0.0902 0.368 0.552 x x
1.75 1.75 63VDC 0.125 0.1440 0.360 0.540 x x
2 002. 32
2.5 02.5 32 0.0324 0.1977 0.095 0.238 x x
3 003. 32 0.0252 0.2922 0.093 0.279 x x
3.5 03.5 32 0.0203 0.4752 0.082 0.287 x x
4 004. 32 0.0169 0.6920 0.079 0.316 x x
5 005. 32 0.0113 0.7398 0.074 0.370 x x
6 006. 24 50A @ 24VDC/12VAC 0.0087 1.3838 0.072 0.432 x x
Max.
Voltage
Rating (V)
Interrupting Rating
50A @ 63VDC
50A @ 32VAC
50A @ 32VDC/12VAC
Nominal
Resistance
(Ohms)
2.024 0.0017 0.550 0.138 x x
0.051 0.1490 0.107 0.214 x x
Melting I2t
2
Nominal
(A2Sec.)
Nominal Voltage
Drop At Rated
3
Current (V)
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.
Nominal Power
Dissipation At
4
Rated Current (W)
Agency Approvals

Surface Mount Fuses
Ceramic Fuse > 438 Series
Temperature Rerating Curve
140
120
100
80
PERCENT OF RATING
60
40
-65 -45 -25 -5 15 35 55 75 95 115 135 155
TEMPERATURE (°C)
Note:
1. Rerating depicted in this curve is in addition to the standard rerating of 20% for
continuous operation.
Example:
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
Average Time Current Curves
.250A
.750A
.375A
.500A
1A
1
CURRENT IN AMPERES
TIME IN SECONDS
0.001
100
10
1
0.1
0.01
0.1
1.25A
2.5A
4A
3.5A
3A
2A
1.5A
1.75A
10 100
6A
5A
Soldering Parameters
Reflow Condition Pb – free assembly
- Temperature Min (T
Pre Heat
- Temperature Max (T
- Time (Min to Max) (ts) 60 – 180 seconds
Average Ramp-up Rate (Liquidus Temp
(T
) to peak)
L
to TL - Ramp-up Rate 5°C/second max.
T
S(max)
Reflow
- Temperature (TL) (Liquidus) 217°C
- Temperature (tL) 60 – 150 seconds
Peak Temperature (TP) 260
Time within 5°C of actual peak
Temperature (t
)
p
Ramp-down Rate 6°C/second max.
Time 25°C to peak Temperature (T
Do not exceed 260°C
Wave Soldering 260°C, 10 seconds max.
) 150°C
s(min)
) 200°C
s(max)
3°C/second max.
+0/-5
°C
10 – 30 seconds
) 8 minutes max.
P
T
Temperature
S(max)
T
S(min)
T
P
T
L
25
time to peak temperature
Preheat
t
S
(t 25ºC to peak)
Ramp-up
t
P
Critical Zone
T
to T
L
P
t
L
Ramp-down
Time
Specifications are subject to change without notice.
© 2013 Littelfuse, Inc.
Revised: 12/19/13

Surface Mount Fuses
Ceramic Fuse > 438 Series
Product Characteristics
Body: Advanced Ceramic
Materials
Terminations: Ag / Ni / Sn (100% Lead-free)
Element Cover Coating: Lead-free Glass
Moisture
Sensitivity Level
IPC/JEDEC J-STD-020C, Level 1
Solderability IPC/EIC/JEDEC J-STD-002B, Condition B
Humidity MIL-STD-202, Method 103B, Conditions D
Resistance to
Solder Heat
MIL-STD-202, Method 210F, Condition B
Dimensions
0.530 +/- 0.150
[0.021 +/- 0.006]
0.85 ± 0.150
[0.033 ± 0.006]
0.502 ± 0.080
[0.020 ± 0.003]
0.432 +/- 0.150
[0.017 +/- 0.006]
1.54 ± 0.150
[0.061 ± 0.006]
Moisture Resistance MIL-STD-202, Method 106G
Thermal Shock
Mechanical Shock
MIL-STD-202, Method 107G,
Condition B-3
MIL-STD-202, Method 213B,
Condition A
Vibration MIL-STD-202, Method 201A
Vibration,
High Frequency
Dissolution of
Metallization
MIL-STD-202, Method 204D,
Condition D
IPC/EIC/JEDEC J-STD-002B,
Condition D
Terminal Strength IEC 60127-4
Part Marking System
Amp Code Marking Code
.250 D
.375 E
.500 F
.750 G
0 01. H
1.25 J
01. 5 K
1.75 L
002. N
02.5 O
003. P
03.5 R
004. S
005. T
006. U
0.60
[0.024]
1.00
[0.039]
0.74
[0.029]
Part Numbering System
SERIES
AMP CODE
1.94
[0.076]
Packaging
Packaging Option Packaging Specification Quantity
8mm Tape and Reel EIA-481, IEC 60286, Part 3 3000 WR
© 2013 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: 12/19/13
0438 005. W R
PACKING CODE
R = Reel Pack
QUANTITY CODE
W = 3000 pcs
Quantity &
Packaging Code