Revised: January 7, 2009

131

Speciﬁcations are subject to change without notice.

Radial Lead Fuses

272/273/274/278/279 Series

Please refer to www.littelfuse.com/series/272.html, /273.html, /274.html,

/278.html or /279.html for current information.

MICRO™ > Very Fast-Acting > 272/273/274/278/279 Series

272-4/278-9

272/273/274/278/279 Series, MICRO™ Very Fast-Acting Fuse

Description

Developed originally for the U.S. Space Program,

MICRO™ fuse provides reliability in a compact design.

The MICRO™ fuse is available in plug–in or radial lead

styles and a complete range of ampere ratings from

1/500 to 5A to suit a wide variety of design needs.

Agency Approvals

Agency Agency File Number Ampere Range

E10480 2mA - 5A

LR 29862 2mA - 5A

FM02 2mA - 5A

Features

Electrical Characteristics

Applications

QPL

% of Ampere

Rating

Ampere Rating Opening Time

100% 1/500–5 4 Hours, Min.

200%

1/500–3/10 5 Seconds, Max.

4/10-5 2 Seconds, Max.

Ampere

Rating

(A)

Amp Code

(for all

above

series)

Max

Voltage

Rating

(V)

Interrupting

Rating

Nominal

Cold

Resistance

(Ohms)

Nominal

Melting

t (A

sec)

Agency Approvals

.002 .002 125

10,000 amperes at

125 VAC/VDC.

2200 0.00000000845

XXX

.005 .005 125 280 0.00000000810

XXX

.010 .010 125 80.0 0.000000462

XXX

.015 .015 125 44.0 0.00000123

XXX

.031 .031 125 16.0 0.00000810

XXX

.050 .050 125 3.20 0.0000666

XXX

.062 .062 125 2.32 0.000115

XXX

.100 .100 125 1.25 0.000385

XXX

.125 .125 125 1.0 0.000691

XXX

.200 .200 125 2.30 0.00409

XXX

.250 .250 125 1.75 0.00640

XXX

.300 .300 125 1.25 0.00945

XXX

.400 .400 125 0.227 0.0251

XXX

.500 .500 125 0.167 0.0716

XXX

.600 .600 125 0.430 0.0411

XXX

.700 .700 125 0.324 0.0710

XXX

.750 .750 125 0.293 0.0900

XXX

.800 .800 125 0.271 0.113

XXX

1.00 001. 125 0.0880 0.0648

XXX

01.5 01.5 125 0.0578 0.160

XXX

2.00 002. 125 0.0425 0.300

XXX

3.00 003. 125 0.0275 0.759

XXX

4.00 004. 125 0.0202 1.38

XXX

5.00 005. 125 0.0156 2.21

XXX

Electrical Characteristics

Military grade availablet

High breaking capacityt

Clear cover option to view t

fuse element status

Available from very low t

ampere of 2mA to 5A

Plug-in with short or long t

leads option

Printed circuit boards t

and similar equipment

Electronic componentst

Revised: January 7, 2009

Introduction to Circuit Protection

Transientology

132

Speciﬁcations are subject to change without notice.

Radial Lead Fuses

272/273/274/278/279 Series

Please refer to www.littelfuse.com/series/272.html, /273.html, /274.html,

/278.html or /279.html for current information.

MICRO™ > Very Fast-Acting > 272/273/274/278/279 Series

Average Time Current Curves

100

0.1

0.01

0.001

100

0.01

0.1

0.005

1/64 A

1/100 A

1/200 A

1/32 A

1/16 A

1/8 A

1/4 A

1/2 A

3/4 A

1 A

1 1/2 A

2 A

3 A

4 A

5 A

TIME IN SECONDS

CURRENT IN AMPERES

Temperature Rerating Curve

Soldering Parameters - Wave Soldering

Dwell Time

100

120

140

160

180

200

220

240

260

280

300

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

Time (Seconds)

Temperature (°C) - Measured on bottom side of board

Cooling Time

Preheat Time

Wave Parameter Lead-Free Recommendation

Preheat:

(Depends on Flux Activation Temperature)

(Typical Industry Recommendation)

Temperature Minimum:

100

° C

Temperature Maximum:

150

° C

Preheat Time: 60-180 seconds

Solder Pot Temperature:

260

° C Maximum

Solder Dwell Time: 2-5 seconds

Recommended Hand-Solder Parameters:

Solder Iron Temperature: 350° C +/- 5°C

Heating Time: 5 seconds max.

Note: These devices are not recommended for IR or

Convection Reﬂow process.

Recommended Process Parameters:

Revised: January 7, 2009

133

Speciﬁcations are subject to change without notice.

Radial Lead Fuses

272/273/274/278/279 Series

Please refer to www.littelfuse.com/series/272.html, /273.html, /274.html,

/278.html or /279.html for current information.

MICRO™ > Very Fast-Acting > 272/273/274/278/279 Series

272-4/278-9

Product Characteristics

Operating Temperature:

273 and 279: –55ºC to +85ºC;

272 and 278: –55ºC to +125ºC

Fuses to MIL SPEC

273 Series is available in CSA LR

29862. Military QPL type (FM02).

To order, change 273 to 274.

Materials

272 and 278 series cap:

Nickel Plated Brass

273, 274 and 279 series cap:

Mirror polished Polycarbonate

Base: R-4 Ryton

Pins: Tin Plated Copper

Product Marking

Current and voltage ratings stamped

on cap

Dimensions

7.30

(.29")

(.17")

8.89

(.35")

2.54 (.10")

7.30

(.29")

25.4 (1.0")

2.54 (.10")

25.4 (1.0")

2.54 (.10")

5.97

(.235")

6.35

(.25")

5.97

(.235")

2.54 (.10")

8.89

(.35")

6.35

(.25")

272 000 Series

273 000 and 274 000 Series

278 000 Series

279 000 Series

(Short Lead, Metal Cap)

(Short Lead, Clear Plastic Cap)

(Long Lead, Metal Cap)

(Long Lead, Clear Plastic Cap)

NOTE: Amperage and voltage rating stamped on cap.

Leads are tin plated copper; .025" diameter.

(.17")

4.32

Part Numbering System

0273 xxxx V

Packaging Code

Amp. Code

Series

Refer to Amp Code column of

Electrical Characteristics Table

V = 5

H = 100

Packaging

Packaging Option Packaging Speciﬁcation Quantity

Quantity &

Packaging Code

Bulk N / A 5 V

Bulk N / A 100 H

Part #	0273.125V
Description	FUSE BOARD MNT 125MA 125VAC/VDC
Category	FUSE
Availability	In Stock
Qty	1150

Qty	Price
1 - 52	$4.77371
53 - 131	$3.79727
132 - 279	$3.58029
280 - 601	$3.32713
602 +	$2.96549

0273.125V

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Technical Document