rev. 10/5/00 precision adjustable shunt regulator features applications ? trimmed bandgap to 0.5% ? battery operating equipments ? wide operating current .......................... 1ma to 150ma ? adjustable supplies ? extended temperature range .................... 0 c to 105 c ? switching power supplies ? low temperature coefficient ............................30 ppm/ c ? error amplifiers ? offered in to-92, soic, sot-89, sot-23-5 ? single supply amplifier ? improved replacement in performance for tl431 ? monitors / vcr / tv ? low cost solution ? personal computers product description the as431 is a 3-terminal adjustable s hunt voltage regulator providing a highly accurate 0.5% bandgap reference. as 431 acts as an open-loop error amplifier with a 2.5v temperature compensation reference. the as431 thermal stability, wide operating current (150ma) and temperature range (0 c to 105 c) makes it suitable for all variety of application that are looking for a low cost solution with high performance. as431 tolerance of 0.5% is proven to be sufficient to overcome all of the other errors in the system to virtually eliminate the need for trimming in the power supply manufactures assembly line and contribute a significant cost savings. the output voltage may be adjusted to any value between v ref and 36 volts with two external resistors. the as431 is operating an extended temperature range of 0c to 105c. the as431 is available in to-92, so-8, sot-89, and sot-23-5 packages . pin configurations as431 sot-23-5 (m5) 3 2 1 top view as431 54 top view as431 sot-89 (m1) 1 2 3 bottom view to-92 (n) 13 2 n/c ref anode cathode cathode anode ref top view 2 1 3 4 8 7 6 5 as431 8-pin surface mount (s) cathode ref anode anode anode anode n/c n/c n/c cathode anode ref
rev. 10/5/00 as431 ordering information part number temperature range package type AS431N 0c to 105c to-92 as431m1 0c to 105c sot-89 as431s 0c to 105c so-8 as431m5 0c to 105c sot-23-5 absolute maximum ratings parameter symbol rating units cathode-anode reverse breakdown v ka 37 v anode-cathode forward current i ak 1 a operating cathode current i ka 150 ma reference input current i ref 10 ma continuous power dissipation at 25 c to-92 sot-23 8l soic sot-89 p d 775 200 750 1000 mw mw mw mw junction temperature t j 150 c storage temperature t stg - 65 to 150 c lead temperature (soldering 10 sec.) t l 300 c stresses greater than those listed under absulute maximum ratings may cause permanent damage to the device. this is a stress ra ting only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specificatio n is not implied. exposure to absolute maximum rating conditions for extended periods may affect reliability. recommended conditions typical thermal resistances parameter symbol rating unit package 0 ja 0 jc typical derating cathode voltage v ka v ref to 20 v to-92 160 c/w 80 c/w 6.3 mw/ c cathode current i k 10 ma sot-23 575 c/w 150 c/w 1.7 mw/ c soic 175 c/w 45 c/w 5.7 mw/ c sot-89 110 c/w 8 c/w 9.1 mw/ c 2.5v + - reference (r) cathode (k) anode (a)
rev. 10/5/00 as431 electrical characteristics at 25c i k @ 10ma v k = v ref , unless otherwise specified. parameter symbol test conditions test circuit as431 unit min typ max reference voltage v ref t a = 25 c over temp. 1 1 2.490 2.469 2.503 2.515 2.536 v v ? v ref with temp. ? tc 1 0.07 0.20 mv/ c ratio of change in v ref to cathode voltage ? v ref ? v k v ref to 10v 10v to 36v 2 -2.7 -2 -1.0 -0.4 0.3 mv/v reference input current i ref 2 0.7 4 a i ref temp deviation ? i ref over temp. 2 0.4 1.2 a min i k for regulation i k(min) 1 0.4 1 ma off state leakage i k(off) v ref = 0v, v ka = 36v 3 0.04 250 na dynamic output impedance z ka 1 0.15 0.5 ? tc = test circuit calculating average temperature coefficient (tc) test circuits ppm mv tc in mv/c = ? v ref (mv) ? t a tc in %/c = v ref at 25c ? t a ? v ref ) ) x 100 tc in ppm/c = v ref at 25c ? t a ? v ref ) ) x 10 6 5000 ? -55 0.06 mv/c ? v ref 0 0 0 % -20 -10 0.5 temperature (c) 0.002 %/c 24 ppm/c -25 0 25 50 75 100 125 i k i ref v in v ka = v ref v in v ka i k r 1 r 2 (v ref ) figure 1b. test circuit 2 figure 1a. test circuit 1 v in v ka i k (off) figure 1c. test circuit 3 i ref
rev. 10/5/00 as431 typical performance curves v r ef - reference voltage (v) v ka - cathode voltage (v) high current operating characteristics figure 3 -2 -1 0 1 2 3 -100 -75 -50 -25 0 25 50 75 100 125 150 i k - cathode current (ma) v ka = v ref temperature range: - 0c to 105 c figure 4 off state leakage -60 -30 0 30 60 90 120 0.01 0.1 1 10 100 t a - ambient temperature ( c) i z off - off state cathode current (na) v ka = 36v v ref = 0v figure 5 t a - ambient temperature ( c) 90 120 reference voltage vs. ambient temperature -60 -30 0 30 60 2.45 2.46 2.47 2.48 2.49 2.50 2.51 2.52 2.53 v ka = v ref i k = 10 ma v ref = 2.500 v at 25 c figure 2 low current operating characteristics v ka - cathode voltage (v) 900 800 700 600 500 400 300 200 100 0 -100 -200 1.0 -1.0 2.0 0 3.0 i k - cathode current ( a) v ka = v ref temperature range: -0c to 125 c 105 c 25 c -0 c
rev. 10/5/00 as431 typical performance curves 30 figure 8 f - frequency (hz) noise voltage nv/ hz 20 10 10 100 1 k 10 k 100 k 0 noise voltage 70 30 40 50 60 v ka = v ref i k = 10 ma t a = 25c t a - free air temperature figure 9 low frequency dynamic output impedance z k a - dynamic impedance ( ? ? ? ? ) -60 -30 0 30 60 90 120 0.0 v ka = v ref i ka = 1 to 100 ma f < 1 khz 0.025 0.050 0.075 0.100 0.125 0.150 figure 7 reference voltage line regulation v ka - cathode voltage (v) v ka - cathode voltage (v) 0 -10 -20 -30 -40 -50 0 3 6 9 121518212427 105 c 75 c 25 c 0 c t a - ambient temperature ( c) figure 6 reference input current i r ef - reference input current ( a) -60 -30 0 30 60 90 120 0 r1 = 10 k ? r2 = i k = 10 ma 0.5 1.0 1.5 2.0 2.5 3.0
rev. 10/5/00 as431 typical performance curves figure 11 10 m dynamic output impedance figure 10 f - frequency (hz) z ka - dynamic impedance 100 0.1 1.0 10 1 k 10 k 100 k 1 m 0.01 t a = 25 c i k = 1 to 100 ma 9 f 15 k 8.25 k gnd out 230 ? i k small signal voltage gain vs. frequency f - frequency (hz) a v - small signal voltage gain (db) 70 20 30 40 10 50 60 1 k 10 k 100 k 1 m 10 m 0 temperature range: -0c to 105 c i k = 10 ma
rev. 10/5/00 as431 typical performance curves out gnd 220 ? f p = 100 khz input monitor 50 ? pulse response figure 12 t - time ( s) input and output voltages (v) 12 -1 0 1 2 3 4 5 6 11 10 9 8 7 6 5 4 3 2 1 0 150 ? 10 k i k c l stability boundary conditions figure 13 c l - load capacitance (pf) i k - cathode current (ma) output input 10 7 10 6 10 5 10 4 10 3 10 2 10 1 10 0 0 10 20 30 40 50 60 70 80 90 100 stability region t a = 25 c a: v ka = v ref b: v ka = 5v at i k = 10 ma c: v ka = 10v at i k = 10 ma d: v ka = 15v at i k = 10 ma d c a b
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