1
© 2009 Littelfuse, Inc.
Specifications are subject to change without notice.
Surface Mount Fuses
438 Series
Ceramic Fuse > 438 Series
Please refer to www.littelfuse.com/series/438.html for current information.
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 AMPERE RANGE
E10480 0.250A – 6A
LR29862 0.250A – 6A
Features
Electrical Characteristics for Series
• OperatingTemperature
from -55ºC to +150ºC
• 100%Lead-free,RoHS
compliant and Halogen-
free
• Suitableforbothleaded
and lead-free reflow /
wave soldering
% of Ampere
Rating Ampere Rating Opening Time at 25ºC
100% 0.250A – 6A 4 Hours, Minimum
250% 0.250A – 6A 5 Seconds, Maximum
Applications
Ampere
Rating
(A)
Amp
Code
Max.
Voltage
Rating (V)
Interrupting Rating
Nominal
Resistance
(Ohms)2
Nominal
Melting I2t
(A2Sec.)3
Nominal Voltage
Drop At Rated
Current (V)4
Nominal Power
Dissipation At
Rated Current (W)
Agency Approvals
0.25 .250 63
50A @ 63VDC
50A @ 32VAC
2.024 0.0017 0.550 0.138 x x
0.375 .375 63 1.247 0.0041 0.488 0.183 x x
0.5 .500 63 0.829 0.0100 0.486 0.243 x x
0.75 .750 63 0.466 0.0281 0.378 0.284 x x
1 001. 63 0.310 0.0593 0.351 0.351 x x
1.25 1.25 63 0.200 0.0510 0.365 0.456 x x
1.5 01.5 63 0.174 0.0902 0.368 0.552 x x
1.75 1.75 63 0.125 0.1440 0.360 0.540 x x
2 002. 32
50A @ 32VDC/12VAC
0.051 0.1490 0.107 0.214 x x
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
Electrical Specifications by Item
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.
• HandheldElectronics
• LCDDisplays
• BatteryPacks
• HardDiskDrives
• SDMemoryCards
• AutomotiveElectronics
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.
Revised: February 15, 2012
Introduction to Circuit Protection
Introduction to Circuit Protection
Transientology
2© 2009 Littelfuse, Inc.
Specifications are subject to change without notice.
Surface Mount Fuses
438 Series
Ceramic Fuse > 438 Series
Please refer to www.littelfuse.com/series/438.html for current information.
Average Time Current Curves
0.001
0.01
0.1
1
10
100
.250A
4A
3.5A
3A
2.5A
2A
1.75A
1.5A
1.25A
1A
.500A
.375A
6A
5A
.750A
TIME IN SECONDS
0.1110 100
CURRENT IN AMPERES
Reflow 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 seconds
Average Ramp-up Rate (Liquidus Temp
(TL) to peak) 3°C/second max.
TS(max) to TL - Ramp-up Rate 5°C/second max.
Reflow - Temperature (TL) (Liquidus) 217°C
- Temperature (tL)60 – 150 seconds
Peak Temperature (TP)260+0/-5 °C
Time within 5°C of actual peak
Temperature (tp)10 – 30 seconds
Ramp-down Rate 6°C/second max.
Time 25°C to peak Temperature (TP)8 minutes max.
Do not exceed 260°C
Soldering Parameters
Temperature Rerating Curve
40
60
80
100
120
140
-65 -45 -25 -5 15 35 55 75 95 115 135 15 5
TEMPERATURE (°C)
PERCENT OF RATING
Example:
For continuous operation at 75 degrees celsius, the fuse should be rerated as follows:
I = (0.80)(0.85)IRAT = (0.68)IRAT
Note:
1. Rerating depicted in this curve is in addition to the standard rerating of 20% for
continuous operation.
Wave Soldering 260°C, 10 seconds max.
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
3
© 2009 Littelfuse, Inc.
Specifications are subject to change without notice.
Surface Mount Fuses
438 Series
Ceramic Fuse > 438 Series
Please refer to www.littelfuse.com/series/438.html for current information.
438 Series
Materials
Body: Advanced Ceramic
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
Product Characteristics
Moisture Resistance MIL-STD-202, Method 106G
Thermal Shock MIL-STD-202, Method 107G,
ConditionB-3
Mechanical Shock MIL-STD-202,Method213B,
Condition A
Vibration MIL-STD-202, Method 201A
Vibration,
High Frequency
MIL-STD-202, Method 204D,
Condition D
Dissolution of
Metallization
IPC/EIC/JEDECJ-STD-002B,
Condition D
Terminal Strength IEC60127-4
Dimensions
1.54 ± 0.150
[0.061 ± 0.006]
0.74
[0.029]
1.00
[0.039]
1.94
[0.076]
0.60
[0.024]
0.502 ± 0.080
[0.020 ± 0.003]
0.530 +/- 0.150
[0.021 +/- 0.006]
0.85 ± 0.150
[0.033 ± 0.006]
0.432 +/- 0.150
[0.017 +/- 0.006]
Packaging
Part Marking System
Packaging Option Packaging Specification Quantity Quantity &
Packaging Code
8mm Tape and Reel EIA-481,IEC60286,Part3 3000 WR
Part Numbering System
0438 005. W R
SERIES
AMP CODE
QUANTITY CODE
PACKING CODE
W = 3000 pcs
R=ReelPack
Amp Code Marking Code
.250 D
.375 E
.500 F
.750 G
001. 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