rev. 10/5/00 precision adjustable shunt regulator features applications ? voltage tolerance ................................................ 0.4% ? battery operating equipment ? wide operating current .....................1ma to 150ma ? adjustable supplies ? extended temperature range ........... -55 c to 125 c ? switching power supplies ? low temperature coefficient ........................30 ppm/ c ? error amplifiers ? improved replacement in performance for lt1431 ? single supply amplifiers ? offered in small low power sot-89 package ? monitors / vcr / tv ? low output noise ? personal computers product description the as1431 is a 3-terminal adjustable s hunt voltage regulator providing a highly accurate 0.4% bandgap reference. as 1431 acts as an open-loop error amplifier with a 2.5v temperature compensation reference. the as1431 thermal stability, wide operating curre nt (150ma) and temperature range (125 c) makes it suitable for all varieties of applications that are looking for a low cost solution with high performance. as1431 tolerance of 0.4% 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. in the standard shunt configuration, the combination of low temperature coefficient (t.c.), sharp turn-on characteristics, low output impedance and programmable output voltage that makes this precision reference an excellent error amplifier. the as1431 is a direct improved replacement for the as431 and tl431 in low voltage, low current applications. pin configurations as1431 sot-89 (m1) front view 1 ref 2 anode 3 cathode 13 2 to-92 (n) bottom view ref anode cathode standard pinout top view 2 1 3 4 8 7 6 5 as1431 anode n/c ref anode n/c anode anode cathode 8-pin surface mount (s) sot-23-5 (m5) 3 2 1 top view as1431 54 ref anode n/c n/c cathode as1431
rev. 10/5/00 as1431 ordering information part number temperature range package type as1431n -55c to 125c to-92 as143s1/s2 -55c to 125c soic as1431m1 -55c to 125c sot-89 as1431m5 -55c to 125c 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 250 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 absolute 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 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 as1431 electrical characteristics are guaranteed over full junction temperature range (-55 c to 125 c). ambient temperature must be derated based on power dissipation and package thermal characteristics. the conditions are: v ka = v ref and i k = 10ma, unless otherwise specified. parameter symbol test conditions test circuit min typ max units reference voltage v ref t a = 25 c 1 2.490 2.500 2.510 v over temp. 1 2.465 2.535 v v ref with temp* tc 1 0.06 0.16 mv/ c ratio of change in v ref to cathode voltage v ref v k = 3v to 36v 2 -2 -1.1 mv/v reference input current i ref r i = 10 k; r 2 = 2 0.7 1.9 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 f < 1 khz i k 1 to 100ma 1 0.15 0.2 ? 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 ? -55 0.06 mv/c ? v ref 0 0 0 % -20 -10 0.5 5000 temperature (c) 0.002 %/c 24 ppm/c -25 0 25 50 75 100 125
rev. 10/5/00 as1431 typical performance curves high current operating characteristics v ka - cathode voltage (v) -2 -1 0 1 2 3 -100 -75 -50 -25 0 25 50 75 100 125 150 figure 3 i k - cathode current (ma) v ka = v ref temperature range: - 55 to 125 c off state leakage -60 -30 0 30 60 90 120 0.01 0.1 1 10 100 figure 4 t a - ambient temperature ( c) i z off - off state cathode current (na) v ka = 18v v ref = 0v t a - ambient temperature ( c) figure 5 reference voltage vs. ambient temperature v r ef - reference voltage (v) -60 -30 0 30 60 90 120 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 low current operating characteristics 900 800 700 600 500 400 300 200 100 0 -100 -200 1.0 -1.0 2.0 0 3.0 v ka - cathode voltage (v) i k - cathode current ( a) v ka = v ref temperature range: - 55 to 125 c 125 c 25 c -55 c figure 2
rev. 10/5/00 as1431 typical performance curves 30 noise voltage nv/vhz 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 figure 7 reference voltage line regulation v ka - cathode voltage (v) v ref - change in reference voltage (mv) 0 -10 -20 -30 -40 -50 0 3 6 9 12 15 18 21 24 27 125 c 75 c 25 c 0 c -55 c 100 k noise voltage figure 8 f - frequency (hz) 70 20 30 40 10 50 60 10 100 1 k 10 k 0 v ka = v ref i k = 10 ma t a = 25 c 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
rev. 10/5/00 as1431 typical performance curves figure 11 gnd out figure 10 dynamic output impedance f - frequency (hz) z ka - dynamic impedance ( ? ? ? ? ) 100 0.1 1.0 10 1 k 10 k 100 k 1 m 10 m 0.01 t a = 25 c i k = 1 to 100 ma f - frequency (hz) 1 k 10 k 100 k 1 m 10 m small signal voltage gain vs. frequency a v - small signal voltage gain (db) 70 20 30 40 10 50 60 0 temperature range: -55 to 125 c i k = 10 ma 9 f 15 k 8.25 k 230 ? i k
rev. 10/5/00 as1431 typical performance curves figure 12 figure 13 pulse response 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 output input out gnd 220 ? f p = 100 khz input monitor 50 ? stability boundary conditions c l - load capacitance (pf) i k - cathode current (ma) 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 150 ? 10 k i k c l
|
