437 LITTELFUSE | Alldatasheet

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Technical content

Features

Electrical Characteristics for Series t 0QFSBUJOH5FNQFSBUVSF from -55ºC to +150ºC t -FBEGSFFBOE RoHS compliant t 4VJUBCMFGPSCPUIMFBEFE and lead-free reflow / wave soldering % of Ampere Rating Ampere Rating Opening Time at 25ºC 100% 250mA - 8A 4 hours, Minimum 250% 750mA - 8A 5 seconds, Maximum 350% 250mA -500mA 5 seconds, Maximum 350% 750mA - 8A 1 second, Maximum

Applications

(A) Amp Code Max. Voltage Rating (V) Interrupting Rating Nominal Resistance (Ohms)2 Nominal Melting I2t (A2Sec.)3 Nominal Voltage Drop At Rated Current (V)4 Nominal Power Dissipation At Rated Current (W) Agency Approvals 500mA .500 63

50 A @ 63 V AC/DC

0.908 0.018 0.52 0.260 x x 2.5A 02.5 32

50 A @ 32 V AC/DC

0.043 0.225 0.14 0.363 x x Electrical Specifications by Item 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 msecs. opening time. 4. Nominal Voltage Drop measured at rated current after temperature has stabilized. t "VUPNPUJWF&MFDUSPOJDT t -$%%JTQMBZT t 4FSWFST t 1SJOUFST t 4DBOOFST t %BUB.PEFNT 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.Revised: August 3, 2009

Introduction to Circuit ProtectionIntroduction to Circuit Protection Transientology 18 © 2009 Littelfuse, Inc. Specifications are subject to change without notice. Surface Mount Fuses Please refer to www.littelfuse.com/series/437.html for current information.

437 Series

Ceramic Fuse > 437 Series Average Time Current Curves 0.001 0.01 0.1 100 0.1 1 10 100 CURRENT IN AMPERES TIME IN SECONDS .250A .375A .500A .750A 1.25 1.5A 1.75 2.5A 3.5A Reflow Condition 1CoGSFFBTTFNCMZ Pre Heat - Temperature Min (Ts(min)) 150°C - Temperature Max (Ts(max)) 200°C - Time (Min to Max) (ts) oTFDPOET Average Ramp-up Rate (Liquidus Temp (TL) to peak) 3°C/second max. TS(max) to TL - Ramp-up Rate 5°C/second max. Reflow - Temperature (TL) (Liquidus) 217°C - Temperature (tL) oTFDPOET Peak Temperature (TP) 260+0/-5 °C Time within 5°C of actual peak Temperature (tp) oTFDPOET Ramp-down Rate 6°C/second max. Time 25°C to peak Temperature (TP) 8 minutes max. Do not exceed 260°C Soldering Parameters T emperature Rerating Curve 100 120 140 -65 -45 -25 -5 15 35 55 75 95 115 135 155 TEMPERATURE (°C) PERCENT OF RATING Time Temperature TP TL TS(max) TS(min) tP tL tS time to peak temperature (t 25ºC to peak) Ramp-down Ramp-up Preheat Critical Zone TL to TP &YBNQMF For continuous operation at 75 degrees celsius, the fuse should be rerated as follows: I = (0.80)(0.85)I RAT = (0.68)IRAT Note: 1 . Rerating depicted in this curve is in addition to the standard rerating of 20% for continuous operation. Wave Soldering 260°C, 10 seconds max.

19© 2009 Littelfuse, Inc. Specifications are subject to change without notice. Surface Mount Fuses Please refer to www.littelfuse.com/series/437.html for current information. Ceramic Fuse > 437 Series Body: Advanced Ceramic T erminations: Ag / Ni / Sn (100% Lead-free) Element Cover Coating: Lead-free Glass Moisture Sensitivity Level *1$+&%&$+45%$ -FWFM $POEJUJPO# Humidity T est .*-45% .FUIPE# $POEJUJPOT% ESD Immunity *&$ L7%JSFDU Resistance to Solder Heat .*-45% .FUIPE' $POEJUJPO# Product Characteristics Moisture Resistance MIL -STD-202, Method 106G Thermal Shock MIL -STD-202, Method 107G, $POEJUJPO# Mechanical Shock .*-45% .FUIPE# Condition A Vibration MIL -STD-202, Method 201A Vibration, High Frequency MIL -STD-202, Method 204D, Condition D Dissolution of Metallization Condition D T erminal Strength *&$ Dimensions 0.520 ± 0.200 [0.020 ± 0.08] 3.200 ± 0.1778 [0.126 ± 0.007] 1.000 [0.039] 1.63 +0.10 / -0.2 N 1.500 [0.059] 1.800 [0.071] 3.500 [0.138] 1.000 [0.039] Packaging Part Marking System Packaging Option Packaging Specification Quantity Quantity & Packaging Code QBSU 3000 WR Part Numbering System 0437 008. W R SERIES AMP CODE QUANTITY CODE PACKING CODE W = 3000 pcs 3FFM1BDL Amp Code Marking Code .250 D .375 E .500 F .750 G 001 . H 1 .25 J 01.5 K 1 .75 L 002. N 02.5 O 003. P 03.5 R 004. S 005. T 007 . W 008. X

Introduction to Circuit ProtectionIntroduction to Circuit Protection Transientology 20 © 2009 Littelfuse, Inc. Specifications are subject to change without notice.