power management 1 www.semtech.com sc4431 shunt regulator with open collector output description revision: september 9, 2003 the sc4431 is a four terminal device for regulating an isolated power supply with output voltages down to 1.5v. it is intended to be used as a replacement for three terminal shunt regulators such as sc431l where the output voltage is too low for the device to function in conjunction with an opto-isolator. sc4431 achieves this by having seperate supply and output pins, allowing the output to sink current at voltages as low as 0.1v, while the supply pin still has sufficient voltage for the device to function. in this way, allowing for a 1.4v drop through an opto-isolator diode, regulation down to 1.5v out can be achieved. the sc4431 shunt regulator is available with three initial reference voltage accuracies (0.5%, 1.0% and 2.0%) in the space saving 5-lead sot-23 package. the three voltage tolerances allow the designer the opportunity to select the proper cost/tolerance for their application. features typical application circuit applications ? telecom power supplies ? opto driver for very low output voltage (1.5v) isolated power supplies ? battery operated applications ? point of use power supplies ? open collector output drives optoisolator with as little as 1.5v input voltage ? trimmed bandgap design - initial accuracies to + 0.5% ? 40ma drive capability ? regulates output as low as 50mv ? wide supply voltage range - 1.5v to 15v ? low supply current - typically 110a ? full industrial temperature range ? sot-23 5 lead package 2v out r1 u1 4n25 5 out r3 6.34k c2 22nf c1 33nf r2 5.1k vin t1 r4 10k primary side controller secondary side rectification and filtering sc4431 1 4 vcc gnd nc ref 3 2 c3 2v output isolated power supply
2 ? 2003 semtech corp. www.semtech.com power management sc4431 t , d e i f i c e p s s s e l n u a v , c 5 2 = c c i , v 2 = t u o n i s e u l a v . a m 2 = d l o b . e g n a r e r u t a r e p m e t g n i t a r e p o l l u f r e v o y l p p a r e t e m a r a pl o b m y ss n o i t i d n o c t s e tn i mp y tx a ms t i n u c c v e g a t l o v y l p p u s t u p n iv c c 5 . 15 1 v t n e r r u c y l p p u s t u p n ii c c v f e r v = t u o 0 1 1 0 0 2 a t n e r r u c y l p p u s t u p n i e t a t s f f oi ) f f o ( c c v f e r v , v 7 8 1 . 1 = t u o v 2 =5 60 0 1a 0 5 1 f e r e g a t l o v e c n e r e f e rv f e r v , 5 . - 1 3 4 4 c s f e r v = t u o 9 1 2 . 14 2 2 . 11 3 2 . 1v 7 0 2 . 13 4 2 . 1 v , 1 - 1 3 4 4 c s f e r v = t u o 2 1 2 . 14 2 2 . 16 3 2 . 1v 0 0 2 . 10 5 2 . 1 v , 2 - 1 3 4 4 c s f e r v = t u o 0 0 2 . 14 2 2 . 10 5 2 . 1v 7 8 1 . 11 6 2 . 1 v n i e g n a h c f e r n i e g n a h c o t e u d c c v v d f e r v d / c c v c c v 5 1 o t v 5 . 1 =85 1v m 0 2 v n i e g n a h c f e r t e u dg n a h c oen i i t u o v d f e r i d / t u o i t u o a m 0 4 o t a m 1 . 0 =88 2v m 6 3 t n e r r u c t u p n i e c n e r e f e ri f e r a m 1 . 0 i t u o a m 0 13 . 05 . 0a 0 . 1 t u o e g a t l o v n o i t a r u t a sv ) t a s ( t u o i t u o i , a m 5 = c c a 0 0 5 =0 55 7v m 0 0 1 v f e r i , v 1 6 2 . 1 = t u o a m 0 4 =5 7 20 0 3v m 0 0 4 t n e r r u c t u p t u o e t a t s f f oi ) f f o ( t u o v f e r v , v 7 8 1 . 1 = t u o v 2 =0 5 . 01a 0 1 r e t e m a r a p l o b m y sm u m i x a ms t i n u e g a t l o v y l p p u s t u p n i v c c 6 1 + o t 5 . 0 -v t n e r r u c n i p c c v i c c 8a m e g a t l o v t u p t u o v t u o c c v o t 5 . 0 -v e g a t l o v e c n e r e f e r ) 1 ( v f e r 4 + o t 5 . 0 -v t n e r r u c t u p t u o s u o u n i t n o c i t u o 0 4a m t n e r r u c t u p n i e c n e r e f e r i f e r 5a m e g n a r e r u t a r e p m e t t n e i b m a g n i t a r e p o t a 5 8 + o t 0 4 -c e g n a r e r u t a r e p m e t n o i t c n u j g n i t a r e p o t j 0 5 1 + o t 0 4 -c e g n a r e r u t a r e p m e t e g a r o t s t g t s 0 5 1 + o t 5 6 -c t n e i b m a o t n o i t c n u j e c n a d e p m i l a m r e h t a j 6 5 2w / c e s a c o t n o i t c n u j e c n a d e p m i l a m r e h t c j 1 8w / c t t a n o i t a p i s s i d r e w o p a c 5 2 =p d 5 7 4w m s d n o c e s 0 1 ) g n i r e d l o s ( e r u t a r e p m e t d a e l t d a e l 0 0 3c ) l e d o m y d o b n a m u h ( g n i t a r d s e d s e2v k absolute maximum rating electrical characteristics (1) if vref will be forced above 1.224v, a resistor must be placed in series with the vcc to limit the icc current below 5ma.
3 ? 2003 semtech corp. www.semtech.com power management sc4431 notes: (1) only available in tape and reel packaging. (suffix ?.tr? e.g. sc4431csk-x.tr). (2) where ?-x? denotes initial reference voltage toler- ance. available options are 0.5% (-.5), 1% (-1) and 2% (-2). r e b m u n t r a p ) 2 ( ) 1 ( e g a k c a p x - k s c 1 3 4 4 c s5 - 3 2 - t o s ordering information pin configurations (sot-23-5 lead (sot-23-5 lead (sot-23-5 lead (sot-23-5 lead (sot-23-5 lead ) (top view) (top view) (top view) (top view) (top view) # n i pe m a n n i pn o i t c n u f n i p 1c c v s i h t s s a p y b o t d e s u e b d l u o h s r o t i c a p a c r s e w o l a . 1 3 4 4 c s e h t r o f n i p y l p p u s t u p n i e h t s i s i h t . c i e h t t a t h g i r d n g o t n i p 2d n g. d n u o r g r e w o p d n a c i g o l 3c n. n o i t c e n n o c o n 4f e r. r e i f i l p m a r o r r e e h t f o t u p n i g n i t r e v n i - n o n e h t o t d e t c e n n o c s i s i h t 5t u o. r o t c e l l o c n e p o n a y l l a i t n e s s e , e c i v e d e h t f o n i p t u p t u o e h t s i s i h t m o r f d e r i u q e r s i r o t i c a p a c ) c i m a r e c ( r s e w o l f n 2 2 a : e t o n . n o i t a r e p o e l b a t s r o f d n g o t n i p s i h t pin descriptions block diagram marking information 4431 top mark bottom mark yyww = datecode (example: 9908) yyww
4 ? 2003 semtech corp. www.semtech.com power management sc4431 typical characteristics typical vref vs ta io = 2ma typical vref vs ta vcc = 2v typical icc off vs ta vo = 2v typical iout vs ta vo = 2v typical iref vs ta vcc = 2v typical vsat vs ta vcc = 2v v ref vs t a i out = 2m a 1.218 1.219 1.220 1.221 1.222 1.223 1.224 1.225 1.226 1.227 1.228 -40-30-20-10 0 1020304050607080 ta(d eg.c .) v re f(v v cc=1.5v v cc= 2v v cc= 5v v cc= 15v i cc o ff vs t a v out = 2v 50e -6 55e -6 60e -6 65e -6 70e -6 -40-30-20-10 0 1020304050607080 ta(d eg.c .) i c c o ff(a i cc_o f f i ref vs t a v cc = 2v 20e-9 25e-9 30e-9 35e-9 40e-9 45e-9 -40-30-20-10 0 1020304050607080 ta(d eg.c .) i r e f(a ) i out= 100ua i out= 1m a i out= 2m a i out= 5m a i out= 10m a i out= 15m a v ref vs t a v cc = 2v 1.222 1.224 1.226 1.228 1.230 1.232 1.234 1.236 -40-30-20-10 0 1020304050607080 ta(d eg.c .) v re f(v i out= 40m a i out= 2m a i out= 100ua i ref vs ta vout = 2v 4e -9 5e -9 6e -9 7e -9 8e -9 9e -9 10e -9 11e -9 12e -9 13e -9 -40-30-20-10 0 1020304050607080 ta(d eg.c .) i re f (a i re f v sat vs t a v cc = 2v 0 50 100 150 200 250 300 350 -40-30-20-10 0 1020304050607080 ta(d eg.c .) v s a t(m v i out= 40m a i out= 5m a
5 ? 2003 semtech corp. www.semtech.com power management sc4431 -0.5000 0.0000 0.5000 1.0000 1.5000 2.0000 2.5000 3.0000 3.5000 1.2248 1.2703 1.3048 1.7030 3.0182 vref(v) icc(ma) vcc=2v,io=1.3ma vcc=5v,io=1.3ma vcc=15v,io=1.3ma -0.5000 0.0000 0.5000 1.0000 1.5000 2.0000 2.5000 3.0000 3.5000 1.2243 1.2700 1.3009 1.7073 3.0073 vref(v) icc(ma) vcc=2v,io=2ma vcc=5v,io=2ma vcc=15v,io=2ma typical icc vs vref, io = 1.3ma, ta = 25 deg.c. typical icc vs vref, io = 2ma, ta = 25 deg.c. 10uf c2 vref u1 sc4431 1 2 4 5 10uf c1 +v adj 10uf c4 j2 1 2 j1 1 2 r2 3.9k +vcc r1 4k 22nf c5 r4 1k j3 1 2 r5 1k +vref_adjust vref vo io c3 icc vs vref test circuit typical characteristics
6 ? 2003 semtech corp. www.semtech.com power management sc4431 typical gain phase r3 5.1k r1 1k for 2ma j5 signal in 1 2 3 4 5 c3 33n c5 22u r2 3.16k u1 sc4431 1 2 3 4 5 vcc gnd nc ref out c2 0.1u j4 gnd 1 2v out c6 22u c4 22u c7 22n c1 10u j3 4v in 1 j1 a 12345 j2 r 12345 r4 4.99k gain phase test circuit sc4431 gain / phase vin = 2v, iout = 2ma, vout = 1.6v -20 -10 0 10 20 30 40 50 60 70 10 100 1000 10000 100000 1000000 freq (hz) gain (db) -150 -100 -50 0 50 100 150 200 phase (deg) gain phase sc4431 gain / phase vin = 4v, iout = 2ma, vout = 2v -20 -10 0 10 20 30 40 50 60 70 80 10 100 1000 10000 100000 1000000 freq (hz) gain (db) -100 -50 0 50 100 150 200 phase (deg) gain phase
7 ? 2003 semtech corp. www.semtech.com power management sc4431 typical applications c4 c1 r1 vref u1 sc4431 1 2 4 5 r5 c3 r4 r3 r2 +vcc q1 power good +v monitor 22nf c2 r1 r5 vref u1 sc4431 1 2 4 5 c1 c2 22n r3 +vprimary c3 c4 r2 pwm disable u2 +vcc r4 +vout secondary r4 +vout r2 c3 vref u1 sc4431 1 2 4 5 +vin q1 r3 c1 r1 22nf c2 power good circuit power good circuit power good circuit power good circuit power good circuit isolated ovp circuit isolated ovp circuit isolated ovp circuit isolated ovp circuit isolated ovp circuit linear regulator circuit linear regulator circuit linear regulator circuit linear regulator circuit linear regulator circuit
8 ? 2003 semtech corp. www.semtech.com power management sc4431 outline drawing - sot-23-5l h c n a r b n a w i a t 0 8 3 3 - 8 4 7 2 - 2 - 6 8 8 : l e t fx a0 9 3 3 - 8 4 7 2 - 2 - 6 8 8 : h b m g d n a l r e z t i w s h c e t m e s h c n a r b n a p a j 0 5 9 0 - 8 0 4 6 - 3 - 1 8 : l e t 1 5 9 0 - 8 0 4 6 - 3 - 1 8 : x a f h c n a r b a e r o k tl e7 7 3 4 - 7 2 5 - 2 - 2 8 : f6 7 3 4 - 7 2 5 - 2 - 2 8 : x a ) . k . u ( d e t i m i l h c e t m e s 0 0 6 - 7 2 5 - 4 9 7 1 - 4 4 : l e t 1 0 6 - 7 2 5 - 4 9 7 1 - 4 4 : x a f e c i f f o i a h g n a h s t0 3 8 0 - 1 9 3 6 - 1 2 - 6 8 : l e 1 3 8 0 - 1 9 3 6 - 1 2 - 6 8 : x a f l r a s e c n a r f h c e t m e s 0 0 - 2 2 - 8 2 - 9 6 1 ) 0 ( - 3 3 : l e t 8 9 - 2 1 - 8 2 - 9 6 1 ) 0 ( - 3 3 : x a f f o y r a i d i s b u s d e n w o - y l l o h w a s i g a l a n o i t a n r e t n i h c e t m e s . a . s . u e h t n i s r e t r a u q d a e h s t i s a h h c i h w , n o i t a r o p r o c h c e t m e s h b m g y n a m r e g h c e t m e s 3 2 1 - 0 4 1 - 1 6 1 8 ) 0 ( - 9 4 : l e t 4 2 1 - 0 4 1 - 1 6 1 8 ) 0 ( - 9 4 : x a f contact information for semtech international ag land pattern - sot-23-5l
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