Surface Mount Fuses Ceramic Fuse > 437 Series 437 Series – 1206 Fast-Acting Fuse RoHS Pb Description This 100% Lead-free, RoHS compliant and Halogen-free fuse series has been designed specifically to provide over current protection to circuits might encounter high working ambient temperatures (up to 150ºC). The general design ensures excellent temperature stability and performance reliability. In addition to this, the high I²t values typical of the Littelfuse Ceramic Fuse family ensure high inrush current withstand capability. Features • Operating Temperature • Suitable for both leaded from -55ºC to +150ºC and lead-free reflow / Agency Approvals wave soldering • 100% Lead-free, Halogen- Agency Agency File Number Ampere Range Free and RoHS compliant • UL Recognized to UL/ CSA/NMX 248-1 and UL/ E10480 0.250A - 8A CSA/NMX 248-14 29862 0.250A - 8A Applications • LCD Displays • Scanners • Servers • Data Modems • Printers Electrical Characteristics for Series % of Ampere Ampere Rating Opening Time at 25ºC Additional Information Rating 100% 250mA - 8A 4 hours, Minimum 250% 750mA - 8A 5 seconds, Maximum 350% 250mA -500mA 5 seconds, Maximum 350% 750mA - 8A 1 second, Maximum Datasheet Resources Samples Electrical Specifications by Item Ampere Max. Nominal Nominal Nominal Voltage Nominal Power Agency Approvals Amp Rating Voltage Interrupting Rating1 Resistance Melting I2t Drop At Rated Dissipation At Rated Code (A) Rating (V) (Ohms)2 (A2Sec.)3 Current (V)4 Current (W) 0.25 .250 125 2.29 0.003 0.78 0.195 x x 50 A @ 125 V AC/DC 0.375 .375 125 1.33 0.01 0.6 0.225 x x 0.5 .500 63 0.908 0.018 0.52 0.26 x x 0.75 .750 63 0.665 0.064 0.45 0.338 x x 1.0 001. 63 0.42 0.1 0.41 0.41 x x 1.25 1.25 63 50 A @ 63 V AC/DC 0.318 0.256 0.4 0.5 x x 1.5 01.5 63 0.209 0.324 0.39 0.585 x x 1.75 1.75 63 0.071 0.075 0.27 0.473 x x 2.0 002. 63 0.058 0.225 0.2 0.4 x x 2.5 02.5 45 0.043 0.441 0.15 0.375 x x 3.0 003. 45 0.033 0.506 0.14 0.42 x x 3.5 03.5 45 50A @ 45V AC/63V DC 0.027 0.777 0.13 0.455 x x 4.0 004. 45 0.022 1.024 0.13 0.52 x x 5.0 005. 45 0.0159 2.3 0.13 0.65 x x 7.0 007. 32 0.01 5.02 0.13 0.91 x x 50 A @ 32 V AC/35 V DC 8.0 008. 32 0.008 7.23 0.13 1.04 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. Contact Littelfuse if application transient surges are less than 1 ms. 4. Nominal Voltage Drop measured at rated current after temperature has stabilized. 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 Re-rating Curve”for additional re-rating information. Devices designed to be mounted with marking code facing up. © 2020 Littelfuse, Inc. Specifications are subject to change without notice. Revised: GD. 10/19/20

Surface Mount Fuses Ceramic Fuse > 437 Series Temperature Re-rating Curve Average Time Current Curves 140 10 .250A .375A.500A .750A1A1.25A 1.5A 1.75A2A2.5A3A3.5A4A5A7A8A G120 N TI A R100 F O 1 T N80 S E D C N R O PE60 EC S N 0.1 40 ME I -65 -45 -25 -5 15 35 55 75 95 115 135 155 TI TEMPERATURE (°C) 0.01 Note: 1. Re-rating depicted in this curve is in addition to the standard re-rating 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 = (0.68)I RAT RAT 0.001 0.1 1 10 100 CURRENT IN AMPERES Soldering Parameters Reflow Condition Pb – free assembly t P - Temperature Min (T ) 150°C T s(min) P Critical Zone Pre Heat - Temperature Max (T ) 200°C Ramp-up TL to TP s(max) - Time (Min to Max) (ts) 60 – 180 seconds TL t Average Ramp-up Rate (Liquidus Temp (TL) to peak) 3°C/second max. eruTS(max) L T to T - Ramp-up Rate 5°C/second max. ta S(max) L r Ramp-down e - Temperature (T) (Liquidus) 217°C p Preheat Reflow L mTS(min) - Temperature (tL) 60 – 150 seconds eT tS Peak Temperature (T) 260+0/-5 °C P Time within 5°C of actual peak Temperature (t) 10 – 30 seconds 25 p time to peak temperature Ramp-down Rate 6°C/second max. (t 25ºC to peak) Time Time 25°C to peak Temperature (T) 8 minutes max. P Do not exceed 260°C Wave Soldering 260°C, 10 seconds max. © 2020 Littelfuse, Inc. Specifications are subject to change without notice. Revised: GD. 10/19/20

Surface Mount Fuses Ceramic Fuse > 437 Series Product Characteristics Body: Advanced Ceramic Thermal Shock MIL-STD-202, Method 107, Condition B Materials Terminations: Ag / Ni / Sn (100% Lead-free) Element Cover Coating: Ceramic/Lead-free Glass Mechanical Shock MIL-STD-202, Method 213, Condition A Moisture Sensitivity Vibration MIL-STD-202, Method 201 IPC/JEDEC J-STD-020, Level 1 Level Vibration, High Frequency MIL-STD-202, Method 204, Condition D Solderability IPC/EIC/JEDEC J-STD-002, Condition B Dissolution of Metallization IPC/EIC/JEDEC J-STD-002, Condition D Humidity Test MIL-STD-202, Method 103, Condition D Terminal Strength IEC 60127-4 Resistance to Solder MIL-STD-202, Method 210, Condition B Heat Moisture Resistance MIL-STD-202, Method 106 Dimensions Part Marking System 3.200 ± 0.1778 Amp Code Marking Code Amp Code Marking Code [0.126 ± 0.007] 0.25 D 2.0 N 0.375 E 2.5 O N 0.5 F 3.0 P 1.63 +0.10 / -0.2 0.75 G 3.5 R [0.064 +0.004 / -0.008] 1.0 H 4.0 S 1.25 J 5.0 T 1.5 K 7.0 W 1.75 L 8.0 X 3.200 ± 0.1778 [0.126 ± 0.007] 1.000 [0.039] HH Part Numbering System 1.63 +0.10 / -0.2 [0.064 +0.004 / -0.008] 0437 008. W R Series Packaging Code AMP Code R = Reel Pack 0.835 ± 0.15 [0.0329 ± 0.006] Quantity Code W = 3000 pcs 0.520 ± 0.200 [0.020 ± 0.008] Packaging [10..000309] [10..500509] Packaging Packaging Quantity Quantity & Packaging Option Specification Code 8mm Tape EIA-481, IEC 60286-3 3000 WR & Reel 1.800 [0.071] 3.500 [0.138] Disclaimer Notice - Littelfuse products are not designed for, and shall not be used for, any purpose (including, without limitation, automotive, military, aerospace, medical, life-saving, life-sustaining or nuclear facility applications, devices intended for surgical implant into the body, or any other application in which the failure or lack of desired operation of the product may result in personal injury, death, or property damage) other than those expressly set forth in applicable Littelfuse product documentation. Warranties granted by Littelfuse shall be deemed void for products used for any purpose not expressly set forth in applicable Littelfuse documentation. Littelfuse shall not be liable for any claims or damages arising out of products used in applications not expressly intended by Littelfuse as set forth in applicable Littelfuse documentation. The sale and use of Littelfuse products is subject to Littelfuse Terms and Conditions of Sale, unless otherwise agreed by Littelfuse. 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. © 2020 Littelfuse, Inc. Specifications are subject to change without notice. Revised: GD. 10/19/20