rev. 9/29/00 as2884 8a low dropout voltage regulator adjustable & fixed 3.3v features applications ? adjustable output down to 1.2v or fixed 3.3v & 5v ? powering intel pentium ? p from +5v supplies ? output current of 8a ? power pc ? supplies ? low dropout voltage ? smps post-regulator ? extremely tight load and line regulation ? high efficiency ?green? computer systems ? current & thermal limiting ? high efficiency linear power supplies ? standard 3-terminal low cost to-220 ? portable instrumentation ? similar to industry standard lt1083/lt1584 ? constant current regulators ? adjustable power supplies ? battery charger product description the as2884 is a low power 8a adjustable voltage regulator that is very easy to use. it requires only 2 external resistors to s et the output voltage. this device is an excellent choice when using powering intel ? microprocessor to convert from +5v to 3.3v supplies, and as a post regulator for switching supplies applications. the as2884 features low dropout of a maximum 1.5 volts. the as2884 offers full protection against over-current faults, reversed input polarity, reversed load insertion, over temperatu re operation, and positive and negative transient voltage. on-chip trimming adjusts the reference voltage to 1%. the i q of this device flows into the load which increases efficiency. the as2884 is offered in a 3-pin to-220 package compatible with older 3-terminal regulators. for a 5a low dropout regulator re fer to the as2850 datasheet. ordering information to-220 3-pin as2884au x = output voltage (i.e. 3.3 for 3.3v, 5.0 for 5.0v etc.) y = output tolerance, a for 1% blank for 2% consult with factory for fixed output voltage front view to-220-3 (u) as2884 1 23 adj/gnd v out v in pin connections
rev. 9/29/00 as2884 absolute maximum ratings power dissipation..........................................internally limited input supply voltage ............................. ......................... 30v lead temp. (soldering, 10 seconds) .............................. 300c input to output voltage differential ..................... .......... 30v storage temperature range ............................ -65 to +150c operating junction temperature range as2884 control section ............................0c to +125c as2884 power transistor..........................0c to +150c electrical characteristics (note 1) at i out = 10ma, t a = 25 c, unless otherwise specified. parameter conditions as2884a as2884 units typ min max min max 3.3v version output voltage (note 2) as2884-3.3v, 0 i out 8a, 4.75v v in 25v 3.3 3.3 3.270 3.240 3.330 3.360 3.230 3.201 3.370 3.399 v 5.0v version output voltage (note 2) as2884-3.3v, 0 i out 8a, 6.5v v in 25v 5.0 5.0 4.950 4.900 5.050 5.100 4.900 4.650 5.100 5.150 all voltage options reference voltage 10 ma i out i fullload 3.3v (v in - v out ) v in max ? v out max 1.250 1.250 1.238 1.225 1.262 1.270 1.238 1.225 1.262 1.270 v mid load current (v in - v out ) = v in max ? v out max 5 10 10 ma line regulation 29v v in - v out v in max ? v out max i load = 10ma 0.015 0.05 0.2 0.5 0.2 0.5 % load regulation 10ma i out i fullload (v in - v out )=3v 0.1 0.2 0.3 0.4 0.3 0.4 % dropout voltage i out =i fullload , ? v ref =1% 1.1 1.2 1.2 v current limit v in - v out =5v 9.5 8.0 8.0 a long term stability t a =125 c, 1000hrs. 0.3 1 1 % adjust pin current t a =25 c 55 90 90 a adjust pin current change 0.2 5 5 a thermal regulation 30ms pulse 0.003 0.01 0.01 %/w temperature stability 0.5 % ripple rejection ratio v in - v out =3v i out =3a, c out = 25 f, c adj = 25 f, f= 120hz 75 60 60 db output noise, rms 10hz to 10khz 0.003 % v o thermal resistance junction-to-case to-220 junction to tab junction to ambient 2.7 0.65 2.7 0.65 c/w the bold specifications apply to the full operating temperature range. note 1 : changes in output voltage due to heating effects are covered under the specification for thermal regulation. note 2 : a 10 f output capacitor is required on as2884
rev. 9/29/00 as2884 typical characteristics reference voltage (v) 1.270 1.260 1.230 temperature (oc) temperature stability 1.250 1.240 short circuit current (a) 12 10 6 4 0 input/output differential (v) 8 2 0 51015202530 short circuit current minimum operating current 7 6 3 0 input/output differential (v) 5 4 1 0 5101520253035 minimum operating current minimum input/output differential (v) 2 0 0 68 10 output current (a) dropout voltage 9 7 5 1 output voltage deviation (%) 0.05 -0.05 -0.15 -0.20 -50 25 150 input/output differential (v) load regulation -25 0 50 100 125 0 adjustment pin current (a) 90 50 20 temperature (oc) 40 30 10 0 adjustment pin current 100 60 70 80 25 50 75 100 125 150 0 -25 -50 25 50 75 100 125 150 0 -25 -50 2 8 10 9 35 75 4 3 2 1 -0.10 0.10 indicates guaranteed test point -40oc t j 150oc 0oc t j 120oc t j =150oc t j =25oc t j = -55oc t j =150oc t j =-55oc t j =25oc i fullload -55oc 150oc 25oc
rev. 9/29/00 as2884 typical applications pentium processor is a trademark of intel corp. power pc is a trademark of ibm corp. in out adj as2884 c 1 r 1 r 2 powering intel pentium tm with as2884 v in intel pentium tm +5v c 2 3.45v v cc in out adj as2884 c 1 r 1 v out fig. 5 typical adjustable regulator v in load adj as2884 fig. 4 8a current output regulator v in c 1 out in r 2 c 2 v out = v ref (1 + r 2 ) + i adj r 2 r 1 r 1 v ref
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