voltage regulators 1 AN6531 4-pin variable positive output voltage regulator overview the AN6531 is a monolithic 4-pin variable positive output voltage regulator. with an external resistor, it pro- vides any stabilized output voltages between 5v and 30v, and is optimum for the power circuits with a current ca- pacity of up to 0.5a. this ic incorporates various protec- tion circuits. features ? wide range of output voltages: v o = 5 to 30v ? built-in thermal overload protection circuit ? built-in overcurrent protection circuit ? built-in aso (area of safe operation) protection circuit block diagram unit : mm ssip004-p-0000 12.5 max. 3.1 2.0 4.0 3?1.0 0.7 0.2 0.5 0.1 2.3 1.5 1.3 2.3 2.3 1.8 9.0 min. 3.3 max. 9.6 +0.5 ?0.1 control 1234 ? error amp. common input output output pass tr + ref. voltage thermal protection current source start circuit short circuit protection r sc
AN6531 voltage regulators 2 absolute maximum ratings at t a = 25 c electrical characteristics at t a = 25 c v cc i cc * p d t opr t stg v a w c c parameter symbol rating unit 40 1.5 7.5 ? 20 to + 75 ? 55 to + 150 supply voltage supply current power dissipation operating ambient temperature storage temperature * the internal circuit is provided with a current limiting circuit. parameter symbol conditions min typ max output voltage tolerance v o 4% v i = v o + 3v to v o + 15v, i o = 5 to 350ma, t j = 25 c % v o = 5v, i o = 200ma, v i = 7.5 to 25v, t j = 25 c line regulation reg in 0.75 % v o = 18v, i o = 5ma, v i = 21 to 33v, t j = 25 c % v o = 18v, i o = 200ma, v i = 21 to 25v, t j = 25 c ma t j = 25 c bias current i bias a 1 t j = 25 c note 1) the specified condition t j = 25 c means that the test should be carried out within so short a test time (within 10ms) that the characteristic value drift due to the chip junction temperature rise can be ignored. note 2) unless otherwise specified, v i = 10v, v o = 5v, i o = 350ma, c i = 0.33 f, c o = 0.1 f control pin current i cont db 80 v i = 8 to 18v, v o = 5v, f = 120hz ripple rejection ratio rr v output noise voltage v no v 2 v o = 5v, f = 10hz to 100khz minimum input/output voltage difference v dif(min) ma 50 i o = 500ma, t j = 25 c 600 1.4 0.67 1 5 8 62 output short-circuit current i os v i = 35v, v o = 5v, t j = 25 c a 1 v o = 5v, t j = 25 c peak output current i op mv/ c 0.5 output voltage temperature coefficient ? v o /t a v 5 v o = 5v control pin voltage v cont t j = 25 c 5.2 3 v o = 5v, v i = 12v, i o = 5 to 500ma, t j = 25 c load regulation reg l % 1 40 4.8 0.4 t j = ? 55 to + 25 c ? 0.5 i o = 5ma t j = 25 to 150 c unit
voltage regulators AN6531 3 main characteristics 0246810 time t ( s) 10 0 ? 10 ? 20 15 10 5 output voltage fluctuation (mv) input voltage v i (v) transient response to input variation 10 8 6 4 2 0 0 20 40 60 80 100 120 140 160 ambient temperature t a ( c ) power dissipation p d ( w ) p d ? t a (1) t c = t a (2) with a 10 c/w heat sink (3) with a 20 c/w heat sink (4) without heat sink (4) (3) (2) (1) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 4 8 12 16 20 24 28 32 input/output voltage difference v dif (v) peak output current i op (a) i o(peak) ? v dif 125 c t j = 0 c 25 c 2.8 2.4 2.0 1.6 1.2 0.8 0.4 ? 80 ? 40 0 40 80 120 160 200 240 junction temperature t j ( c) minimum input/output voltage difference v dif(min) (v) ripple rejection ratio rr (db) v dif(min) ? t j i o = 500ma 200ma 100ma 10ma 0ma 120 100 80 60 40 20 0 10 100 1k 10k 100k 1m frequency f (hz) rr ? f v i = 8 to 18v v o = 5v i o = 20ma 0 20406080100 time t ( s) 0.5 0 ? 0.5 ? 1.0 1.0 0.5 0 output voltage fluctuation (v) load current i l (a) transient response to load variation 6 5 4 3 2 1 0 0 0.2 0.4 0.6 0.8 1.0 1.2 output current i o (a) output voltage v o (v) current limiting characteristic 10 100 1k 10k 100k 1m frequency f (hz) output impedance z o (m ? ) z o ? f v i = 10v v o = 5v t j = 25 c 10 4 10 3 10 2 10 v i = 10v v o = 5v i o = 20ma c o = 0.1 f t a = 25 c
AN6531 voltage regulators 4 basic regulator circuit application circuit examples 1. current bootstrap circuit 2. current bootstrap circuit (with current limiting circuit) + v o v o = v cont c i is necessary when the v i line is long. c o improves the transient response. 4 3 1 2 c o 0.1 f 0.33 f v cont c i + v 1 AN6531 r 1 r 2 cont input output common r 1 r 1 + r 2 (v cont ? 5v, r 1 = 5k ? ) v o 1 2 4 3 0.33 f 0.1 f v i i o i p i r r 3 = v be(q1) ( + 1) i p ? i o r 3 r 2 r 1 6 ? 5k ? cont input output common q 1 AN6531 v o 1 2 4 3 0.33 f 0.1 f v i i o i p i r i e2 i e1 r sc = v be(q2) i e1(max) r 3 = v be(q1) + i e1 r sc i o ? i e1 i e2(max) = i p(max) ? v be(q1) + v be(q2) r 3 r 3 r sc r 2 r 1 5k ? cont input output common q 1 q 2 AN6531 6 ?
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