Radial Lead Fuses MICRO™ > Very Fast-Acting > 272/273/274/278/279 Series 272/273/274/278/279 Series, QPL 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. Features t Military grade available t High breaking capacity t Available from very low ampere of 2mA to 5A t Clear cover option to view t Plug-in with short or long leads option fuse element status Agency Approvals Applications QPL Agency File Number Ampere Range E10480 2mA - 5A t Printed circuit boards and similar equipment LR 29862 2mA - 5A Electrical Characteristics FM02 2mA - 5A t Electronic components % of Ampere Rating Ampere Rating Opening Time 100% 1/500–5 4 Hours, Min. 1/500–3/10 5 Seconds, Max. 4/10-5 2 Seconds, Max. 200% Electrical Characteristics Ampere Rating (A) .002 .005 .010 .015 .031 .050 .062 .100 .125 .200 .250 .300 .400 .500 .600 .700 .750 .800 1.00 01.5 2.00 3.00 4.00 5.00 Amp Code (for all above series) .002 .005 .010 .015 .031 .050 .062 .100 .125 .200 .250 .300 .400 .500 .600 .700 .750 .800 001. 01.5 002. 003. 004. 005. Max Voltage Rating (V) 125 125 125 125 125 125 125 125 125 125 125 125 125 125 125 125 125 125 125 125 125 125 125 125 Interrupting Rating 10,000 amperes at 125 VAC/VDC. © 2009 Littelfuse, Inc. Specifications are subject to change without notice. Please refer to www.littelfuse.com/series/272.html, /273.html, /274.html, /278.html or /279.html for current information. Nominal Cold Resistance (Ohms) 2200 280 80.0 44.0 16.0 3.20 2.32 1.25 1.0 2.30 1.75 1.25 0.227 0.167 0.430 0.324 0.293 0.271 0.0880 0.0578 0.0425 0.0275 0.0202 0.0156 131 Revised: January 7, 2009 Agency Approvals Nominal Melting I2t (A2 sec) 0.00000000845 0.00000000810 0.000000462 0.00000123 0.00000810 0.0000666 0.000115 0.000385 0.000691 0.00409 0.00640 0.00945 0.0251 0.0716 0.0411 0.0710 0.0900 0.113 0.0648 0.160 0.300 0.759 1.38 2.21 QPL 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 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 X X X X X X X X X X X X 272/273/274/278/279 Series 272-4/278-9 Agency Fuses Introduction toRadial CircuitLead Protection Transientology MICRO™ > Very Fast-Acting > 272/273/274/278/279 Series 1/2 A 3/4 A 1A 1 1/2 A 2A 3A 4A 5A 1/4 A 1/8 A 1/16 A 1/32 A 100 1/100 A 1/64 A Average Time Current Curves 1/200 A Temperature Rerating Curve TIME IN SECONDS 10 1 0.1 0.01 0.001 0.005 1 0.1 CURRENT IN AMPERES 0.01 10 100 Soldering Parameters - Wave Soldering Recommended Process Parameters: 280 260 Wave Parameter 240 220 Preheat: 200 (Depends on Flux Activation Temperature) 180 160 140 120 80 60 40 Lead-Free Recommendation (Typical Industry Recommendation) Temperature Minimum: 100° C Temperature Maximum: Preheat Time: 150° C 60-180 seconds 100 Solder Pot Temperature: 260° C Maximum Solder Dwell Time: 2-5 seconds Recommended Hand-Solder Parameters: 240 230 220 210 200 190 180 170 160 150 140 130 120 110 90 100 80 70 60 50 40 30 0 0 20 20 10 Temperature (°C) - Measured on bottom side of board 300 Time (Seconds) Solder Iron Temperature: 350° C +/- 5°C Heating Time: 5 seconds max. Cooling Time Preheat Time Dwell Time Note: These devices are not recommended for IR or Convection Reflow process. 272/273/274/278/279 Series 132 Revised: January 7, 2009 © 2009 Littelfuse, Inc. Specifications are subject to change without notice. Please refer to www.littelfuse.com/series/272.html, /273.html, /274.html, /278.html or /279.html for current information. Radial Lead Fuses MICRO™ > Very Fast-Acting > 272/273/274/278/279 Series Dimensions Product Characteristics 272 000 Series 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. (Short Lead, Metal Cap) 5.97 (.235") 4.32 (.17") 2.54 (.10") 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 Materials 7.30 (.29") 278 000 Series (Long Lead, Metal Cap) 5.97 (.235") 7.30 (.29") 25.4 (1.0") 2.54 (.10") Current and voltage ratings stamped on cap Product Marking 273 000 and 274 000 Series (Short Lead, Clear Plastic Cap) Part Numbering System 6.35 (.25") 0273 xxxx V 8.89 (.35") 4.32 (.17") 2.54 (.10") Amp. Code 279 000 Series Refer to Amp Code column of Electrical Characteristics Table (Long Lead, Clear Plastic Cap) 6.35 (.25") Packaging Code 8.89 (.35") 25.4 (1.0") V=5 H = 100 2.54 (.10") NOTE: Amperage and voltage rating stamped on cap. Leads are tin plated copper; .025" diameter. Packaging Packaging Option Packaging Specification Quantity Quantity & Packaging Code Bulk N/A 5 V Bulk N/A 100 H © 2009 Littelfuse, Inc. Specifications are subject to change without notice. Please refer to www.littelfuse.com/series/272.html, /273.html, /274.html, /278.html or /279.html for current information. 133 Revised: January 7, 2009 272/273/274/278/279 Series 272-4/278-9 Series