Axial Lead & Cartridge Fuses PICO® ll > Very Fast-Acting Fuse > 251/253 Series 251/253 Series, PICO® II Very Fast-Acting Fuse PS QPL E Description The PICO® II Very Fast-Acting Fuse is designed to meet an extensive array of performance characteristics in a space-saving subminiature package. Features • Very fast-acting • Halogen-free available • Small size • Wide operating • Wide current rating range temperature range (0.062A- 15A) • Low temperature re-rating Applications Agency Approvals Secondary protection for space constrained applications Agency File Number Agency Ampere Range • Flat–panel display TV • Power supply 253 Series 251 Series • LCD monitor • Audio/Video system E10480 0.062A - 15A • LCD backlight inverter • Lighting system 29862 0.062A - 15A • Office machines • Medical equipment PS PSE_NBK200416-JP1021 1A - 5A E Electrical Characteristics for Series J50158379 0.500A - 10A % of Ampere Ampere Rating Opening Time FM10 N/A 0.062A - 15A Rating 100% 0.062A - 15A 4 Hours, Min. 0.500A, 1A, 2A, 2009010207366577 2.5A, 3A, 4A, 5A 0.062A - 7A 1 Second, Max. 200% 10A 3 Seconds, Max. Note: See Electrical Specifications by Item table for specific approved ratings. 12 - 15A 10 Seconds, Max. 0.500A, 1A, 2A, 275% 2.5A, 3A, 4A, 5A, 300 msecs., Max. Additional Information 7A, 10A 0.5A, 1A, 2A, 2.5A, 400% 30 msecs., Max. 3A, 4A, 5A, 7A, 10A 0.500A, 1A, 2A, 1000% 2.5A, 3A, 4A, 5A, 4 msecs., Max. 7A, 10A Datasheet Resources Samples 251 Series 251 Series 251 Series Datasheet Resources Samples 253 Series 253 Series 253 Series © 2018 Littelfuse, Inc. Application testing is strongly recommended.Specifications are subject to change without notice. Revised: 05/31/18

Axial Lead & Cartridge Fuses PICO® ll > Very Fast-Acting Fuse > 251/253 Series Electrical Specifications by Item Max Nominal Nom Agency Approvals Ampere Ordering Ordering Nominal Amp Voltage Interrupting Cold Voltage Rating Number Number Melting QPL Code Rating Rating Resistance Drop PS (A) (Std.) (Mil.) I2t (A2 sec) E 253 Series (V) (Ohms) (V) Only .062 .062 251.062 253.062 125 7.000 0.000113 1.4 x x x .125 .125 251.125 253.125 125 1.700 0.00174 0.285 x x x .200 .200 251.200 253.200 125 0.895 0.0048 0.345 x x .250 .250 251.250 253.250 125 0.665 0.0116 0.24 x x x .375 .375 251.375 253.375 125 0.395 0.0296 0.215 x x x .500 .500 251.500 253.500 125 0.302 0.0598 0.2165 x x x x x .630 .630 251.630 125 0.205 0.08 0.188 x x .750 .750 251.750 253.750 125 0.175 0.153 0.176 x x x x 1.00 001. 251001. 253001. 125 0.128 0.256 0.194 x x x x x x 1.25 1.25 2511.25 125 300 A @ 0.100 0.390 0.2 x x x 125VDC 1.50 01.5 25101.5 25301.5 125 0.0823 0.587 0.21 x x x x x 2.00 002. 251002. 253002. 125 50A@125VAC 0.0473 0.405 0.141 x x x x x x 2.50 02.5 25102.5 125 0.0360 0.721 0.132 x x x x x 3.00 003. 251003. 253003. 125 0.0295 1.19 0.131 x x x x x x 3.50 03.5 25103.5 125 0.0240 1.58 0.1205 x x x x 4.00 004. 251004. 253004. 125 0.0204 2.45 0.114 x x x x x x 5.00 005. 251005. 253005. 125 0.0158 4.14 0.11 x x x x x x 7.00 007. 251007. 253007. 125 0.0107 10.4 0.102 x x x x 10.0 010. 251010. 253010. 125 0.0072 25.5 0.1 x x x x 12.0 012. 251012. 32 300A@32VDC0.0059 45.2 0.0878 x x 15.0 015. 251015. 253015. 32 & 50A@32VAC0.00446 68.8 0.071 x x x Note: Higher ampere ratings are available. Please contact Littelfuse Technical Support or your Littelfuse products representative for assistance. © 2018 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 05/31/18

Axial Lead & Cartridge Fuses PICO® ll > Very Fast-Acting Fuse > 251/253 Series Temperature Re-rating Curve Average Time Current Curves 100 .062A .125A .250A.375A.500A.630A.750A1A1.25A1.5A2A2.5A3A3.5A4A5A7A10A12A15A 10 S D N O C 1 E S N E I M TI 0.1 Note: 1. Re-rating depicted in this curve is in addition to the standard derating of 25% for continuous operation. 0.01 Soldering Parameters 0.001 Recommended Process Parameters: 0.050.1 1 10 100 1000 CURRENT IN AMPERES Lead-Free Recommendation Wave Parameter for 251 Series only 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 Soldering 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 © 2018 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 05/31/18

Axial Lead & Cartridge Fuses PICO® ll > Very Fast-Acting Fuse > 251/253 Series Product Characteristics Encapsulated, Epoxy-coated Body MIL-STD-202, Method 201 (10–55 Materials 251 Series: Pure tin-coated copper wire leads Vibration Hz); Method 204, Test Condition C 253 Series: Solder-coated copper wire leads (55–2000 Hz at 10 G’s Peak) Solderability MIL-STD-202, Method 208 MIL-STD-202, Method 213, Test Shock Condition I (100 G’s peak for 6 MIL-STD-202, Method 211, Test Condition A msecs.) Lead Pull Force (will withstand a 7lbs. axial pull test) MIL-STD-202, Method 302, Insulation Resistance For fuses to MIL-PRF-23419, FM10 change the Test Condition A (10,000 ohms Fuses To MIL (After Opening): series number from minimum at 100 volts) SPEC 251 to 253 Moisture Resistance MIL-STD-202, Method 106 Operating –55ºC to +125ºC (Consider re-rating) Temperature Resistance to Soldering Withstands 60 seconds above 200OC Heat and up to 260ºC, maximum Flammability Rating UL 94V–0 Dimensions Part Numbering System 251 Series Markings 0251 xxxx N R T1 L (T1 lead length) 62.7 (2.468") Series 27.78 52.4 (2.062")* 27.78 251 = Standard type (1.094") 7.11 (.280") (1.094") 253 = Military type Current Rating 1 A LF Refer to Amp Code column of 2.80 Electrical Specifications Table 6.35 (.25") 5.0 (.197") (.11") 6.35 (.25") tape MAX tape Quantity 1 A LF N = 5000 P = 2000 Wire Diameter: M = 1000 0.64 (.025") for 0.062-10 amp, H = 100 0.81 (.032") for 12-15 amp Type of Packaging R = Reel 251 Series (Halogen-free Version) Markings 253 Series Markings A = Ammo Pack (T1 lead length) (T3 lead length) X = Loose Pack 62.7 (2.468") 83.31 (3.28") 52.4 (2.062")* Lead Length 27.78 27.78 38.1 73.0 (2.874")** 38.1 The default lead length for Ammo pack( 1a.n0d9 4") 7.11 (.280") (1.094") (1.5") 7.11 (.280") (1.5") Loose pack is now T1 for 251 series, and remains T3 for 253 series, therefore: LF 1 A LF 1 A T1 = 52.4mm (2.062”), 251 series only* 2.80 6.35 (.25") 5.0 (.197") 2.61M (A.1X03") 6.35 (.25") Borl a7n3km =m 5 (22..48m74m”) (f2o.r0 62256”3.) 3 sft5eoa rrp(i .ee22s55*"1)* serie5s.0* ( .197") (M.1A1X") 6.3t5a p(.e25") tape tape Option Codes 1 A LF LF 1 A L = RoHS + HF Wire Diameter: (Only applies to 251 Series) 0.64 (.025") for 0.62-10.0 amp, Wire Diameter: 0.81 (.032") for 12-15 amp 0.64 (.025") for 0.062-10 amp, 0.81 (.032") for 15 amp Packaging Packaging Quantity & Packaging Option Specification Packaging Code *T1: 52.4mm (2.062") Please refer to EIA 296 Tape and Reel available quantities above in "Part **T3: 73mm (2.874') Numbering EIA 296 Tape and Reel System” The default lead length for both ammo pack and loose pack is T1 for 251 and is T3 for 253. Notes: * T1 dimension is defined as the length of the component between the two tapes. The full component length is 62.7mm (2.468"). T1 length is for 251 series only. ** T3 dimension is defined as the length of the component between the two tapes. The full component length is 83.3.7mm (3.28”). T3 length is for 253 series only. Disclaimer Notice - Information furnished is believed to be accurate and reliable. However, users should independently evaluate the suitability of and test each product selected for their own applications. Littelfuse products are not designed for, and may not be used in, all applications. Read complete Disclaimer Notice at: www.littelfuse.com/disclaimer-electronics. © 2018 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 05/31/18