Littelfuse 438 User Manual

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

• OperatingTemperature

from -55ºC to +150ºC

• 100%Lead-free,RoHS

compliant and Halogen­free

Applications

• HandheldElectronics

• LCDDisplays

• BatteryPacks

Additional Information

Datasheet

• Suitableforbothleaded

and lead-free reflow /
wave soldering

• HardDiskDrives

• SDMemoryCards

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