21 ? 2009 littelfuse, inc. specications are subject to change without notice. surface mount fuses 438 series ceramic fuse > 438 series please refer to www.littelfuse.com/series/438.html for current information. 438 series 438 series C 0603 fast-acting fuse description the 438 series is a 100% lead-free, rohs compliant and halogen-free fuse series designed specically to provide over-current protection to circuits that operate under high working ambient temperature up to 150oc. the general design ensures excellent temperature stability and performance reliability. the high i2t values which is typical in the littelfuse ceramic fuse family ensure high inrush current withstand capability. agency approvals agency agency file number ampere range e10480 0.250a C 6a lr29862 0.250a C 6a features electrical characteristics for series t 0 q f s b u j o h 5 f n q f s b u v s f from -55oc to +150oc t - f b e g s f f
3 p ) 4 compliant and halogen- free t 4 v j u b c m f g p s c p u i m f b e f e and lead-free reow / wave soldering % of ampere rating ampere rating opening time at 25oc 100% 0.250a C 6a 4 hours, minimum 250% 0.250a C 6a 5 seconds, maximum applications ampere rating (a) amp code max. voltage rating (v) interrupting rating nominal resistance (ohms) 2 nominal melting i 2 t (a 2 sec.) 3 nominal voltage drop at rated current (v) 4 nominal power dissipation at rated current (w) agency approvals 0.25 .250 32 50 a @ 32 vdc 2.024 0.0017 0.550 0.138 x x 0.375 .375 32 1.247 0.0041 0.488 0.183 x x 0.5 .500 32 0.829 0.0100 0.486 0.243 x x 0.75 .750 32 0.466 0.0281 0.378 0.284 x x 1 001. 32 0.310 0.0593 0.351 0.351 x x 1.25 1.25 32 0.200 0.0510 0.365 0.456 x x 1.5 01.5 32 0.174 0.0902 0.368 0.552 x x 1.75 1.75 32 0.125 0.1440 0.360 0.540 x x 2 002. 32 0.051 0.1490 0.107 0.214 x x 2.5 02.5 32 0.0324 0.1977 0.095 0.238 x x 3 003. 32 0.0252 0.2922 0.093 0.279 x x 3.5 03.5 32 0.0203 0.4752 0.082 0.287 x x 4 004. 32 0.0169 0.6920 0.079 0.316 x x 5 005. 32 0.0113 0.7398 0.074 0.370 x x 6 006. 24 50 a @ 24 vdc 0.0087 1.3838 0.072 0.432 x x electrical specications 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 msec. opening time. 4. nominal voltage drop measured at rated current after temperature has stabilized. t ) b o e i f m e & m f d u s p o j d t t - $ % % j t q m b z t t # b u u f s z 1 b d l t t ) b s e % j t l % s j w f t t 4 % . f n p s z $ b s e t t " v u p n p u j w f & m f d u s p o j d t 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 curvefor additional rerating information. devices designed to be mounted with marking code facing up. revised: august 21, 2009
introduction to circuit protection introduction to circuit protection transientology 22 ? 2009 littelfuse, inc. specications are subject to change without notice. surface mount fuses 438 series ceramic fuse > 438 series please refer to www.littelfuse.com/series/438.html for current information. average time current curves 0.001 0.01 0.1 1 10 100 .250a 4a 3.5a 3a 2.5a 2a 1.75a 1.5a 1.25a 1a .500a .375a 6a 5a .750a time in seconds 0.1 1 10 100 current in amperes reow condition 1 c o g s f f b t t f n c m z pre heat - temperature min (t s(min) ) 150c - temperature max (t s(max) ) 200c - time (min to max) (t s ) 60 C 180 seconds average ramp-up rate (liquidus temp (t l ) to peak) 3c/second max. t s(max) to t l - ramp-up rate 5c/second max. reow - temperature (t l ) (liquidus) 217c - temperature (t l ) 60 C 150 seconds peak temperature (t p ) 260 +0/-5 c time within 5c of actual peak temperature (t p ) 10 C 30 seconds ramp-down rate 6c/second max. time 25c to peak temperature (t p ) 8 minutes max. do not exceed 260c soldering parameters temperature rerating curve 40 60 80 100 120 140 -6 5 -4 5 -2 5 - 5 1 5 3 5 55 7 5 9 5 11 5 13 5 1 55 temperature (c) percent of rating & y b n q m f for continuous operation at 75 degrees celsius, the fuse should be rerated as follows: i = (0.80)(0.85)i rat = (0.68)i rat note: 1. rerating depicted in this curve is in addition to the standard rerating of 20% for continuous operation. wave soldering 260c, 10 seconds max. time temperature t p t l t s(max) t s(min) 25 t p t l t s time to peak temperature (t 25oc to peak) ramp-down ramp-up preheat critical zone t l to t p
23 ? 2009 littelfuse, inc. specications are subject to change without notice. surface mount fuses 438 series ceramic fuse > 438 series please refer to www.littelfuse.com/series/438.html for current information. 438 series materials body: advanced ceramic terminations: ag / ni / sn (100% lead-free) element cover coating: lead-free glass moisture sensitivity level * 1 $ + & % & $ + 4 5 % $
- f w f m solderability * 1 $ & * $ + & % & $ + 4 5 % #
$ p o e j u j p o # humidity . * - 4 5 %
. f u i p e #
$ p o e j u j p o t % esd immunity * & $
l 7 % j s f d u resistance to solder heat . * - 4 5 %
. f u i p e '
$ p o e j u j p o # product characteristics moisture resistance mil-std-202, method 106g thermal shock mil-std-202, method 107g, $ p o e j u j p o # mechanical shock . * - 4 5 %
. f u i p e #
condition a vibration mil-std-202, method 201a vibration, high frequency mil-std-202, method 204d, condition d dissolution of metallization * 1 $ & * $ + & % & $ + 4 5 % #
condition d terminal strength * & $ dimensions 1.54 0.150 [0.061 0.006] 0.74 [0.029] 1.00 [0.039] 1.94 [0.076] 0.60 [0.024] 0.502 0.080 [0.020 0.003] 0.530 +/- 0.150 [0.021 +/- 0.006] 0.85 0.150 [0.033 0.006] 0.432 +/- 0.150 [0.017 +/- 0.006] packaging part marking system packaging option packaging specication quantity quantity & packaging code 8mm tape and reel & * " * & $
q b s u
3000 wr part numbering system 0438 005. w r series amp code quantity code packing code w = 3000 pcs 3 3 f f m 1 b d l 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 006. u
introduction to circuit protection introduction to circuit protection transientology 24 ? 2009 littelfuse, inc. specications are subject to change without notice.
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