1 astec semiconductor as2431 precision adjustable shunt reference features temperature-compensated: 15 ppm/?c trimmed bandgap reference internal amplifier with 100 ma capability multiple temperature ranges low frequency dynamic output impedance: < 450 m? low output noise description the as2431 is a three-terminal adjustable shunt regulator providing a highly accu- rate bandgap reference. the adjustable shunt regulator is ideal for a wide variety of linear applications that can be implemented using external components to obtain adjustable currents and voltages. in the standard shunt configuration, the combination of low temperature coeffi- cient (tc), sharp turn-on characteristics, low output impedance and program- mable output voltage make this precision reference an excellent error amplifier. the as2431 is a direct replacement for the as431 in low voltage, low current appli- cations. it is also available in the very small footprint sot-23. semiconductor pin configuration ? top view cathode to-92 (lp) soic (d) anode reference cathode reference anode anode n/c cathode anode anode n/c sot-89 (s) sot-23/3l (vs) anode reference 1 2 3 4 8 7 6 5 cathode reference anode circuit type: precision adjustable shunt regulator temperature range: a = 0 c to 70 c b = 0 c to 105 c c = ?0 c to +85 c d = ?5 c to +125 c bandgap tolerance: 2 1 r4 r5 r25 = 2% = 1% = 0.4% = 0.5% = 0.25% as2431 a 2 d 7 packaging option: a b t 7 13 package style: d lp s vs = ammo pack = bulk = tube = tape and reel (7" reel dia) = tape and reel (13" reel dia) = soic = to-92 = sot-89 = sot-23/3l ordering information
2 astec semiconductor as2431 precision adjustable shunt reference functional block diagram absolute maximum ratings parameter symbol rating units cathode-anode reverse breakdown v ka 18 v anode-cathode forward current i ak 1 a operating cathode current i ka 100 ma reference input current i ref 1 ma continuous power dissipation at 25 ? c p d t o-92 775 mw 8l soic 750 mw sot -89 1000 mw sot -23/3l 200 mw junction t emperature t j 150 ? c storage t emperature t stg e65 to 150 ? c lead t emp, soldering 10 seconds t l 300 ? c stresses greater than those listed under absolute maximum ra tings may cause permanent damage to the device. this is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operati onal sec - tions of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may af fect reliability . e + reference (r) anode (a) cathode (k) 2.5 v recommended conditions parameter symbol rating unit cathode v oltage v ka v ref to 18 v cathode current i k 10 ma t ypical thermal resistances package q ja q jc t ypical derating t o-92 160 ? c/w 80 ? c/w 6.3 mw/ ? c soic 175 ? c/w 45 ? c/w 5.7 mw/ ? c sot -89 1 10 ? c/w 8 ? c/w 9.1 mw/ ? c sot -23/3l 575 ? c/w 150 ? c/w 1.7 mw/ ? c
3 astec semiconductor as2431 precision adjustable shunt reference electrical characteristics electrical characteristics are guaranteed over full junction temperature range (0 to 105 ? c). ambient temperature must be derated based on power dissipation and package thermal characteristics. the conditions are: v ka = v ref and i k = 10 ma unless otherwise stated. t est as2431 (0.25%) as2431 (0.5%) t est parameter symbol condition min. t yp. max. min. t yp. max. unit circuit reference v oltage v ref t a = 25 ? c 2.494 2.500 2.506 2.490 2.500 2.515 v 1 over temp. 2.480 2.518 2.480 2.530 v 1 ? v ref with t emp* tc 0.04 0.06 0.04 0.06 mv/ ? c 1 ratio of change in ? v ref v ref to 10 v e2.7 e1.01 e2.7 e1.01 v ref to cathode ? v k mv/v 2 v oltage 10 v to 18 v e2 .0 e0.4 0.3 e2 .0 e0.4 0.3 reference input i ref 0.7 4 0.7 4 a 2 current i ref t emp deviation ? i ref over temp. 0.4 1.2 0.4 1.2 a 2 min i k for regulation i k(min) 0.4 1 0.4 1 ma 1 of f state leakage i k(of f) v ref = 0 v , 0.04 500 0.04 500 na 3 v ka = 18 v dynamic output z ka f 2 1 khz 0.45 1 0.45 1 ? 1 impedance i k = 1 to 150 ma t est as2431 (1.0%) as2431 (2.0%) t est parameter symbol condition min. t yp. max. min. t yp. max. unit circuit reference v oltage v ref t a = 25 ? c 2.470 2.495 2.520 2.440 2.495 2.550 v 1 over temp. 2.450 2.540 2.415 2.580 v 1 ? v ref with t emp* tc 0.04 0.06 0.04 0.06 mv/ ? c 1 ratio of change in ? v ref v ref to 10 v e2.7 e1.01 e2.7 e1.01 v ref to cathode ? v k mv/v 2 v oltage 10 v to 18 v e2 .0 e0.4 0.3 e2 .0 e0.4 0.3 reference input i ref 0.7 4 0.7 4 a 2 current i ref t emp deviation ? i ref over temp. 0.4 1.2 0.4 1.2 a 2 min i k for regulation i k(min) 0.4 1 0.4 1 ma 1 of f state leakage i k(of f) v ref = 0 v , 0.04 500 0.04 500 na 3 v ka = 18 v dynamic output z ka f 2 1 khz 0.45 1 0.45 1 ? 1 impedance i k = 1 to 150 ma *calculating a verage t emperature coef ficient (tc). refer to following page.
4 astec semiconductor as2431 precision adjustable shunt reference t est circuits figure 1a. t est circuit 1 figure 1b. t est circuit 2 figure 1c. t est circuit 3 a verage t emperature coefficient 0 ?0 ?0 0.5 5000 0 0 0 15 0.07 mv/ c 0.003%/ c 27 ppm/ c 30 45 60 75 90 105 ppm mv % d v ref d t t emperature ( c) ?tc in mv/ c = ?tc in %/ c = d t a d t a x 100 d v ref (mv) v ref at 25 c d v ref ?tc in ppm/ c = d t a x 10 6 v ref at 25 c d v ref r 1 r 2 i k v in v ka (v ref ) i ref i ref i k v in v ka = v ref i k (off) v in v ka
5 astec semiconductor as2431 precision adjustable shunt reference t ypical performance figure 2 figure 4 figure 3 figure 5 i k ?cathode current ( m a) 900 700 600 500 400 300 200 100 0 ?00 ?00 800 ?.0 0 1.0 v ka ?cathode v oltage (v) 2.0 3.0 low current operating characteristics v ka = v ref t emperature range: ?5 to 125 c 125 c 25 c ?5 c i k ?cathode current (ma) 150 125 100 75 50 25 0 ?5 ?0 ?5 ?00 ? ? 0 1 2 3 v ka ?cathode v oltage (v) high current operating characteristics v ka = v ref t emperature range: ?5 to 125 c i z off ?off state cathode current (na) 100 10 1 0.1 0.01 ?0 ?0 0 30 t a ?ambient t emperature ( c) 60 90 120 off state leakage v ka = 18 v v ref = 0 v v ref ?reference v oltage (v) 3.53 2.52 2.51 2.50 2.49 2.48 2.47 2.46 2.45 ?0 ?0 0 30 t a ?ambient t emperature ( c) 60 90 120 v ka = v ref i k = 10 ma reference v oltage vs ambient t emperature v ref = 2.500 v at 25 c
6 astec semiconductor as2431 precision adjustable shunt reference t ypical performance curves figure 6 figure 8 figure 7 figure 9 3.0 2.5 2.0 1.5 1.0 0.5 0 ?0 ?0 0 30 60 90 120 i ref ?reference input current ( m a) t a ?ambient t emperature ( c) reference input current r1 = 10 k w r2 = i k =10 ma 0 ? ?0 ?5 ?0 ?5 0 3 6 9 v ka ?cathode v oltage (v) 12 15 18 d v ref ?change in reference v oltage (mv) i k = 10 ma t emperature range: ?5 to 125 c ?0 c 25 c 75 c 125 c reference v oltage line regulation 70 60 50 40 30 20 10 0 10 100 1 k f ?frequency (hz) 10 k 100 k noise v oltage nv/ hz v ka = v ref i k = 10 ma t a = 25 c noise v oltage z ka ?dynamic impedance ( w ) 0.150 0.125 0.100 0.075 0.050 0.025 0.0 ?0 ?0 0 30 t a ?free air t emperature 60 90 120 v ka = v ref i ka = 1 to 100 ma f 1 khz low frequency dynamic output impedance
7 astec semiconductor as2431 precision adjustable shunt reference t ypical performance curves figure 10 figure 1 1 100 10 1.0 z ka ?dynamic impedance ( w ) 0.1 0.01 1 k 10 k 100 k f ?frequency (hz) 1 m 10 m t a = 25 c i k = 1 to 100 ma dynamic output impedance 70 60 50 40 30 20 10 0 1 k 10 k 100 k 1 m 10 m f ?frequency (hz) 230 w i k a v ?small signal v oltage gain (db) t emperature range: ?5 to 125 c i k = 10 ma out gnd 15 k 8.25 k 9 m f small signal v oltage gain vs. frequency
8 astec semiconductor as2431 precision adjustable shunt reference t ypical performance curves figure 12 figure 13 6 5 4 3 input and output v otages (v) 2 1 0 ? 0 1 2 3 4 5 6 7 t ?t ime (ms) 8 9 10 11 12 input output pulse response input monitor 220 w 50 w out gnd f p = 100 khz 100 90 80 70 60 50 40 30 20 10 0 10 0 10 1 10 2 10 3 c l ?load capacitance (pf) 10 4 10 5 10 6 10 7 150 w c l 10 k i k a c d b t a = 25 c stability boundar y conditions stability region i k ?cathode current (ma) a: v ka = v ref b: v ka = 5 v at i k = 10 ma c: v ka = 10 v at i k = 10 ma d: v ka = 15 v at i k = 10 ma
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