Back Light Driver

8/3/2019 Back Light Driver

1/18

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Q u a l i f i c a t i o n i n A c c o r d a n c e W i t h A E C - Q 1 0 0 ( 1 ) T h e T P S 6 1 0 4 0 / 4 1 i s a h i g h - f r e q u e n c y b o o s t c o n v e r t e r d e d i c a t e d f o r s m a l l t o m e d i u m L C D b i a s Q u a l i f i e d F o r A u t o m o t i v e A p p l i c a t i o n s u p p l y a n d w h i t e L E D b a c k l i g h t s u p p l i e s . T h e d e v i c e C u s t o m e r - S p e c i f c C o n f i g u r a t i o n C o n t r o l C a n i s i d e a l t o g e n e r a t e o u t p u t v o l t a g e s u p t o 2 8 V f r o m a

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A d j u s t a b l e O u t p u t V o l t a g e R a n g e U p t o 2 8 V T h e T P S 6 1 0 4 0 / 4 1 o p e r a t e s w i t h a s w i t c h i n g f r e - 4 0 0 - m A ( T P S 6 1 0 4 0 ) a n d 2 5 0 - m A ( T P S 6 1 0 4 1 ) q u e n c y u p t o 1 M H z . T h i s a l l o w s t h e u s e o f s m a l l

e x t e r n a l c o m p o n e n t s u s i n g c e r a m i c a s w e l l a s t a n t a - I n t e r n a l S w i t c h C u r r e n t l u m o u t p u t c a p a c i t o r s . T o g e t h e r w i t h t h e t i n y S O T 2 3 U p t o 1 - M H z S w i t c h i n g F r e q u e n c y p a c k a g e , t h e T P S 6 1 0 4 0 / 4 1 g i v e s a s m a l l o v e r a l l

2 8 - A T y p i c a l N o L o a d Q u i e s c e n t C u r r e n t s o l u t i o n s i z e . T h e T P S 6 1 0 4 0 h a s a n i n t e r n a l 4 0 0 - m A 1 - A T y p i c a l S h u t d o w n C u r r e n t s w i t c h c u r r e n t l i m i t , w h i l e t h e T P S 6 1 0 4 1 h a s a 2 5 0 - m A s w i t c h c u r r e n t l i m i t , o f f e r i n g l o w e r o u t p u t I n t e r n a l S o f t s t a r t v o l t a g e r i p p l e a n d a l l o w s t h e u s e o f a s m a l l e r f o r m

A v a i l a b l e i n a T i n y 5 - P i n S O T 2 3 P a c k a g e f a c t o r i n d u c t o r f o r l o w e r p o w e r a p p l i c a t i o n s . T h e l o w ( 1 )C o n t a c t T e x a s I n s t r u m e n t s f o r d e t a i l s . Q 1 0 0 q u i e s c e n t c u r r e n t ( t y p i c a l l y 2 8 A ) t o g e t h e r w i t h a n q u a l i f i c a t i o n d a t a a v a i l a b l e o n r e q u e s t . o p t i m i z e d c o n t r o l s c h e m e , a l l o w s d e v i c e o p e r a t i o n a t

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D E T A I L E D D E S C R I P T I O N

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T h e T P S 6 1 0 4 0 / 4 1 o p e r a t e s w i t h a n i n p u t v o l t a g e r a n g e o f 1 . 8 V t o 6 V a n d c a n g e n e r a t e o u t p u t v o l t a g e s u p t o 2 8 V . T h e d e v i c e o p e r a t e s i n a p u l s e f r e q u e n c y m o d u l a t i o n ( P F M ) s c h e m e w i t h c o n s t a n t p e a k c u r r e n t c o n t r o l . T h i s c o n t r o l s c h e m e m a i n t a i n s h i g h e f f i c i e n c y o v e r t h e e n t i r e l o a d c u r r e n t r a n g e , a n d w i t h a s w i t c h i n g f r e q u e n c y

u p t o 1 M H z , t h e d e v i c e e n a b l e s t h e u s e o f v e r y s m a l l e x t e r n a l c o m p o n e n t s . T h e c o n v e r t e r m o n i t o r s t h e o u t p u t v o l t a g e , a n d a s s o o n a s t h e f e e d b a c k v o l t a g e f a l l s b e l o w t h e r e f e r e n c e v o l t a g e o f t y p i c a l l y 1 . 2 3 3 V , t h e i n t e r n a l s w i t c h t u r n s o n a n d t h e c u r r e n t r a m p s u p . T h e s w i t c h t u r n s o f f a s s o o n a s t h e i n d u c t o r c u r r e n t r e a c h e s t h e i n t e r n a l l y s e t p e a k c u r r e n t o f t y p i c a l l y 4 0 0 m A ( T P S 6 1 0 4 0 ) o r 2 5 0 m A ( T P S 6 1 0 4 1 ) . S e e t h e P e a k C u r r e n t C o n t r o l s e c t i o n f o r m o r e i n f o r m a t i o n . T h e s e c o n d c r i t e r i a t h a t t u r n s o f f t h e s w i t c h i s t h e m a x i m u m o n - t i m e o f 6 s ( t y p i c a l ) . T h i s i s j u s t t o l i m i t t h e m a x i m u m o n - t i m e o f t h e c o n v e r t e r t o c o v e r f o r e x t r e m e c o n d i t i o n s . A s t h e s w i t c h i s t u r n e d o f f , t h e e x t e r n a l S c h o t t k y d i o d e i s f o r w a r d b i a s e d d e l i v e r i n g t h e c u r r e n t t o t h e o u t p u t . T h e s w i t c h r e m a i n s o f f f o r a m i n i m u m o f 4 0 0 n s ( t y p i c a l ) , o r u n t i l t h e f e e d b a c k v o l t a g e d r o p s b e l o w t h e r e f e r e n c e v o l t a g e a g a i n . U s i n g t h i s P F M p e a k c u r r e n t c o n t r o l s c h e m e , t h e c o n v e r t e r o p e r a t e s i n d i s c o n t i n u o u s c o n d u c t i o n m o d e ( D C M ) w h e r e t h e s w i t c h i n g f r e q u e n c y d e p e n d s o n t h e o u t p u t c u r r e n t , w h i c h r e s u l t s i n h i g h e f f i c i e n c y o v e r t h e e n t i r e l o a d c u r r e n t r a n g e . T h i s r e g u l a t i o n s c h e m e i s i n h e r e n t l y s t a b l e , a l l o w i n g a w i d e r s e l e c t i o n r a n g e f o r t h e i n d u c t o r a n d o u t p u t c a p a c i t o r .

T h e i n t e r n a l s w i t c h t u r n s o n u n t i l t h e i n d u c t o r c u r r e n t r e a c h e s t h e t y p i c a l d c c u r r e n t l i m i t ( I L I M ) o f 4 0 0 m A ( T P S 6 1 0 4 0 ) o r 2 5 0 m A ( T P S 6 1 0 4 2 ) . D u e t o t h e i n t e r n a l p r o p a g a t i o n d e l a y o f t y p i c a l 1 0 0 n s , t h e a c t u a l c u r r e n t e x c e e d s t h e d c - c u r r e n t l i m i t t h r e s h o l d b y a s m a l l a m o u n t . T h e t y p i c a l p e a k c u r r e n t l i m i t c a n b e c a l c u l a t e d :

T h e h i g h e r t h e i n p u t v o l t a g e a n d t h e l o w e r t h e i n d u c t o r v a l u e , t h e g r e a t e r t h e p e a k .

B y s e l e c t i n g t h e T P S 6 1 0 4 0 o r T P S 6 1 0 4 1 , i t i s p o s s i b l e t o t a i l o r t h e d e s i g n t o t h e s p e c i f i c a p p l i c a t i o n c u r r e n t l i m i t

r e q u i r e m e n t s . A l o w e r c u r r e n t l i m i t s u p p o r t s a p p l i c a t i o n s r e q u i r i n g l o w e r o u t p u t p o w e r a n d a l l o w s t h e u s e o f a n i n d u c t o r w i t h a l o w e r c u r r e n t r a t i n g a n d a s m a l l e r f o r m f a c t o r . A l o w e r c u r r e n t l i m i t u s u a l l y h a s a l o w e r o u t p u t v o l t a g e r i p p l e a s w e l l .

A l l i n d u c t i v e s t e p - u p c o n v e r t e r s e x h i b i t h i g h i n r u s h c u r r e n t d u r i n g s t a r t - u p i f n o s p e c i a l p r e c a u t i o n i s m a d e . T h i s c a n c a u s e v o l t a g e d r o p s a t t h e i n p u t r a i l d u r i n g s t a r t u p a n d m a y r e s u l t i n a n u n w a n t e d o r e a r l y s y s t e m s h u t d o w n .

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T h e T P S 6 1 0 4 0 / 4 1 l i m i t s t h i s i n r u s h c u r r e n t b y i n c r e a s i n g t h e c u r r e n t l i m i t i n t w o s t e p s s t a r t i n g f r o m

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VI N I n p u t v o l t a g e r a n g e 1 . 8 6 V

IQ O p e r a t i n g q u i e s c e n t c u r r e n t I O U T = 0 m A , n o t s w i t c h i n g , V F B = 1 . 3 V 2 8 5 0 A IS D S h u t d o w n c u r r e n t E N = G N D 0 . 1 1 A

VU V L O U n d e r - v o l t a g e l o c k o u t t h r e s h o l d 1 . 5 1 . 7 V

E N A B L E

VI H E N h i g h l e v e l i n p u t v o l t a g e 1 . 3 V

VI L E N l o w l e v e l i n p u t v o l t a g e 0 . 4 V

II E N i n p u t l e a k a g e c u r r e n t E N = G N D o r V I N 0 . 1 1 A

P O W E R S W I T C H A N D C U R R E N T L I M I T

V s w M a x i m u m s w i t c h v o l t a g e 3 0 V

to f f M i n i m u m o f f t i m e 2 5 0 4 0 0 5 5 0 n s

to n M a x i m u m o n t i m e 4 6 7 . 5 s

RD S ( O N ) M O S F E T o n - r e s i s t a n c e V I N = 2 . 4 V ; I s w = 2 0 0 m A ; T P S 6 1 0 4 0 6 0 0 1 1 0 0 m

RD S ( O N ) M O S F E T o n - r e s i s t a n c e V I N = 2 . 4 V ; I s w = 2 0 0 m A ; T P S 6 1 0 4 1 7 5 0 1 3 0 0 m

M O S F E T l e a k a g e c u r r e n t V s w = 2 8 V 1 1 0 A

IL I M M O S F E T c u r r e n t l i m i t T P S 6 1 0 4 0 3 2 5 4 0 0 5 0 0 m A

IL I M M O S F E T c u r r e n t l i m i t T P S 6 1 0 4 1 2 0 0 2 5 0 3 2 5 m A

O U T P U T

VO U T A d j u s t a b l e o u t p u t v o l t a g e r a n g e ( 1 ) VI N 2 8 V

Vr e f I n t e r n a l v o l t a g e r e f e r e n c e 1 . 2 3 3 V

IF B F e e d b a c k i n p u t b i a s c u r r e n t V F B = 1 . 3 V 1 A

VF B F e e d b a c k t r i p p o i n t v o l t a g e 1 . 8 V VI N 6 V 1 . 2 1 . 2 3 3 1 . 2 7 V

1 . 8 V VI N 6 V ; V O U T = 1 8 V ; I l o a d = 1 0 m A ; C f f L i n e r e g u l a t i o n ( 2 ) 0 . 0 5 % / V = n o t c o n n e c t e d

L o a d r e g u l a t i o n ( 2 ) VI N = 2 . 4 V ; V O U T = 1 8 V ; 0 m A IO U T 3 0 m A 0 . 1 5 % / m A

( 1 ) C a n n o t b e p r o d u c t i o n t e s t e d . A s s u r e d b y d e s i g n . ( 2 ) T h e l i n e a n d l o a d r e g u l a t i o n d e p e n d o n t h e e x t e r n a l c o m p o n e n t s e l e c t i o n . S e e t h e A p p l i c a t i o n S e c t i o n f o r f u r t h e r i n f o r m a t i o n .

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T Y P I C A L C H A R A C T E R I S T I C S

70

72

74

76

78

80

82

84

86

88

90

0.10 1 10 100

VI = 5 V

VI = 3.6 V

VI = 2.4 V

Efficiency-%

IO - Output Current - mA

VO = 18 V

70

72

74

76

78

80

82

84

86

88

90

0.10 1 10 100

TPS61040

TPS61041

Efficiency-%

IL - Load Current - mA

L = 10 H

VO = 18 V


T a b l e o f G r a p h s

F I G U R E

v s L o a d c u r r e n t 1 , 2 , 3 E f f i c i e n c y

v s I n p u t v o l t a g e 4

IQ Q u i e s c e n t c u r r e n t v s I n p u t v o l t a g e a n d t e m p e r a t u r e 5

VF B F e e d b a c k v o l t a g e v s T e m p e r a t u r e 6

IS W S w i t c h c u r r e n t l i m i t v s T e m p e r a t u r e 7

v s S u p p l y v o l t a g e , T P S 6 1 0 4 1 8 IC L S w i t c h c u r r e n t l i m i t

v s S u p p l y v o l t a g e , T P S 6 1 0 4 0 9

v s T e m p e r a t u r e 1 0 R D So n R D S o n

v s S u p p l y v o l t a g e 1 1

L i n e t r a n s i e n t r e s p o n s e 1 2

L o a d t r a n s i e n t r e s p o n s e 1 3

S t a r t - u p b e h a v i o r 1 4

E F F I C I E N C Y E F F I C I E N C Y v s v s

O U T P U T C U R R E N T L O A D C U R R E N T

F i g u r e 1 . F i g u r e 2 .

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70

72

74

76

78

80

82

84

86

88

90

0.10 1 10 100

L = 10 H

L = 3.3 H

Efficiency-%

IL - Load Current - mA

VO = 18 V

70

72

74

76

78

80

82

84

86

88

90

1 2 3 4 5 6

IO = 10 mA

IO = 5 mA

Efficiency-%

VI - Input Voltage - V

L = 10 H

VO = 18 V

1.23

1.232

1.234

1.236

1.238

1.24

-40 -20 0 20 40 60 80 100 120

VCC = 2.4 V

-FeedbackVoltage

-V

VFB

TA - Temperature - C

0

5

10

15

20

25

30

35

40

1.8 2.4 3 3.6 4.2 4.8 5.4 6

QuiescentCurrent-

A

VI - Input Voltage - V

TA = 85C

TA = 27C

TA = -40C

T P S 6 1 0 4 0 - Q 1 T P S 6 1 0 4 1 - Q 1

S G L S 2 7 6 J A N U A R Y 2 0 0 5

E F F I C I E N C Y E F F I C I E N C Y v s v s

L O A D C U R R E N T I N P U T V O L T A G E

F i g u r e 3 . F i g u r e 4 .

T P S 6 1 0 4 0 Q U I E S C E N T C U R R E N T F E E D B A C K V O L T A G E

v s v s I N P U T V O L T A G E F R E E - A I R T E M P E R A T I R E

F i g u r e 5 . F i g u r e 6 .

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230

250

270

290

310

330

350

370

390

410

430

-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90

TPS61040

TPS61041

TA - Temperature - C

I(SW)-SwitchCurrentLimit-mA

240

242

244

246

248

250

252

254

256

258

260

1.8 2.4 3 3.6 4.2 4.8 5.4 6

-CurrentLimit-mA

I(CL)

VCC - Supply Voltage - V

TA = 27C

0

200

400

600

800

1000

1200

4030 20 10 0 10 20 30 40 50 60 70 80 90

rDS(on)StaticDrain-SourceOn-StateResistancem

TA Temperature C

TPS61041

TPS61040

380

385

390

395

400

405

410

415

420

1.8 2.4 3 3.6 4.2 4.8 5.4 6

-CurrentLimit-mA

I(CL)

VCC - Supply Voltage - V

TA = 27C


T P S 6 1 0 4 0 / 4 1 T P S 6 1 0 4 1 S W I T C H C U R R E N T L I M I T C U R R E N T L I M I T

v s v s F R E E - A I R T E M P E R A T U R E S U P P L Y V O L T A G E

F i g u r e 7 . F i g u r e 8 .

T P S 6 1 0 4 0 T P S 6 1 0 4 0 / 4 1 C U R R E N T L I M I T S T A T I C D R A I N - S O U R C E O N - S T A T E R E S I S T A N C E

v s v s S U P P L Y V O L T A G E F R E E - A I R T E M P E R A T U R E

F i g u r e 9 . F i g u r e 1 0 .

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VI

2.4 V to 3.4 V

VO

100 mV/div

200 S/div

VO = 18 V

0

100

200

300

400

500

600

700

800

900

1000

1.8 2.4 3 3.6 4.2 4.8 5.4 6

rDS(on)

StaticDrain-SourceOn-StateResistanc

em

VCC Supply Voltage V

TPS61041

TPS61040

VO

5 V/div

EN

1 V/div

II

50 mA/div

VO = 18 V

VO

1 mA to 10 mA

200 S/div

VO

100 mA/div

VO = 18 V

T P S 6 1 0 4 0 - Q 1 T P S 6 1 0 4 1 - Q 1

S G L S 2 7 6 J A N U A R Y 2 0 0 5

T P S 6 1 0 4 0 / 4 1 S T A T I C D R A I N - S O U R C E O N - S T A T E R E S I S T A N C E

v sS U P P L Y V O L T A G E

F i g u r e 1 1 . F i g u r e 1 2 . L i n e T r a n s i e n t R e s p o n s e

F i g u r e 1 3 . L o a d T r a n s i e n t R r e s p o n s e F i g u r e 1 4 . S t a r t - U p B e h a v i o r

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A P P L I C A T I O N I N F O R M A T I O N

I N D U C T O R S E L E C T I O N , M A X I M U M L O A D C U R R E N T

fSmax+Vin

min (VoutVin)

IP L Vout

( 2 )

fSIload+ 2 Iload (VoutVin) Vd)

I 2P L

( 3 )

load max+ h

I 2P L fSmax

2 (Vout* Vin) ( 4 )


S i n c e t h e P F M p e a k c u r r e n t c o n t r o l s c h e m e i s i n h e r e n t l y s t a b l e , t h e i n d u c t o r v a l u e d o e s n o t a f f e c t t h e s t a b i l i t y o f t h e r e g u l a t o r . T h e s e l e c t i o n o f t h e i n d u c t o r t o g e t h e r w i t h t h e n o m i n a l l o a d c u r r e n t , i n p u t a n d o u t p u t v o l t a g e o f t h e a p p l i c a t i o n d e t e r m i n e s t h e s w i t c h i n g f r e q u e n c y o f t h e c o n v e r t e r . D e p e n d i n g o n t h e a p p l i c a t i o n , i n d u c t o r v a l u e s

b e t w e e n 2 . 2 H u p t o 4 7 H a r e r e c o m m e n d e d . T h e m a x i m u m i n d u c t o r v a l u e i s d e t e r m i n e d b y t h e m a x i m u m o n t i m e o f t h e s w i t c h , t y p i c a l l y 6 s . T h e p e a k c u r r e n t l i m i t o f 4 0 0 m A / 2 5 0 m A ( t y p i c a l l y ) s h o u l d b e r e a c h e d w i t h i n t h i s 6 - s p e r i o d f o r p r o p e r o p e r a t i o n .

T h e i n d u c t o r v a l u e d e t e r m i n e s t h e m a x i m u m s w i t c h i n g f r e q u e n c y o f t h e c o n v e r t e r . T h e r e f o r e , s e l e c t t h e i n d u c t o r v a l u e t h a t e n s u r e s t h e m a x i m u m s w i t c h i n g f r e q u e n c y a t t h e c o n v e r t e r m a x i m u m l o a d c u r r e n t i s n o t e x c e e d e d . T h e m a x i m u m s w i t c h i n g f r e q u e n c y i s c a l c u l a t e d b y t h e f o l l o w i n g f o r m u l a :

W h e r e :

IP = P e a k c u r r e n t a s d e s c r i b e d i n t h e p r e v i o u s p e a k c u r r e n t c o n t r o l s e c t i o n

L = S e l e c t e d i n d u c t o r v a l u e V i n m i n = T h e h i g h e s t s w i t c h i n g f r e q u e n c y o c c u r s a t t h e m i n i m u m i n p u t v o l t a g e

I f t h e s e l e c t e d i n d u c t o r v a l u e d o e s n o t e x c e e d t h e m a x i m u m s w i t c h i n g f r e q u e n c y o f t h e c o n v e r t e r , t h e n e x t s t e p i s t o c a l c u l a t e t h e s w i t c h i n g f r e q u e n c y a t t h e n o m i n a l l o a d c u r r e n t u s i n g t h e f o l l o w i n g f o r m u l a :

W h e r e :


L = S e l e c t e d i n d u c t o r v a l u e

Il o a d = N o m i n a l l o a d c u r r e n t

V d = R e c t i f i e r d i o d e f o r w a r d v o l t a g e ( t y p i c a l l y 0 . 3 V )

A s m a l l e r i n d u c t o r v a l u e g i v e s a h i g h e r c o n v e r t e r s w i t c h i n g f r e q u e n c y , b u t l o w e r s t h e e f f i c i e n c y .

T h e i n d u c t o r v a l u e h a s l e s s e f f e c t o n t h e m a x i m u m a v a i l a b l e l o a d c u r r e n t a n d i s o n l y o f s e c o n d a r y o r d e r . T h e b e s t w a y t o c a l c u l a t e t h e m a x i m u m a v a i l a b l e l o a d c u r r e n t u n d e r c e r t a i n o p e r a t i n g c o n d i t i o n s i s t o e s t i m a t e t h e e x p e c t e d c o n v e r t e r e f f i c i e n c y a t t h e m a x i m u m l o a d c u r r e n t . T h i s n u m b e r c a n b e t a k e n o u t o f t h e e f f i c i e n c y g r a p h s s h o w n i n F i g u r e 1 , F i g u r e 2 , F i g u r e 3 , a n d F i g u r e 4 . T h e m a x i m u m l o a d c u r r e n t c a n t h e n b e e s t i m a t e d a s f o l l o w s :

W h e r e :



f Sm a x = M a x i m u m s w i t c h i n g f r e q u e n c y a s c a l c u l a t e d p r e v i o u s l y

= E x p e c t e d c o n v e r t e r e f f i c i e n c y . T y p i c a l l y 7 0 % t o 8 5 % .

1 0


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S E T T I N G T H E O U T P U T V O L T A G E

Vout

+ 1.233 V 1) R1R2

( 5 )

CFF+

1

2 pfS

20R1

( 6 )

T P S 6 1 0 4 0 - Q 1 T P S 6 1 0 4 1 - Q 1

S G L S 2 7 6 J A N U A R Y 2 0 0 5

T h e m a x i m u m l o a d c u r r e n t o f t h e c o n v e r t e r i s t h e c u r r e n t a t t h e o p e r a t i o n p o i n t w h e r e t h e c o n v e r t e r s t a r t s t o e n t e r t h e c o n t i n u o u s c o n d u c t i o n m o d e . U s u a l l y t h e c o n v e r t e r s h o u l d a l w a y s o p e r a t e i n d i s c o n t i n u o u s c o n d u c t i o n m o d e .

L a s t , t h e s e l e c t e d i n d u c t o r s h o u l d h a v e a s a t u r a t i o n c u r r e n t t h a t m e e t s t h e m a x i m u m p e a k c u r r e n t o f t h e c o n v e r t e r ( a s c a l c u l a t e d i n t h e p e a k c u r r e n t c o n t r o l s e c t i o n ) . U s e t h e m a x i m u m v a l u e f o r I L I M f o r t h i s c a l c u l a t i o n .

A n o t h e r i m p o r t a n t i n d u c t o r p a r a m e t e r i s t h e d c r e s i s t a n c e . T h e l o w e r t h e d c r e s i s t a n c e , t h e h i g h e r t h e e f f i c i e n c y o f t h e c o n v e r t e r . S e e t h e T a b l e 1 a n d t h e T y p i c a l A p p l i c a t i o n s s e c t i o n f o r t h e i n d u c t o r s e l e c t i o n .

T a b l e 1 . R e c o m m e n d e d I n d u c t o r f o r T y p i c a l L C D B i a s S u p p l y ( s e e F i g u r e 1 5 )

D E V I C E I N D U C T O R V A L U E C O M P O N E N T S U P P L I E R C O M M E N T S

1 0 H S u m i d a C R 3 2 - 1 0 0 H i g h e f f i c i e n c y

1 0 H S u m i d a C D R H 3 D 1 6 - 1 0 0 H i g h e f f i c i e n c y

T P S 6 1 0 4 0 1 0 H M u r a t a L Q H 4 C 1 0 0 K 0 4 H i g h e f f i c i e n c y

4 . 7 H S u m i d a C D R H 3 D 1 6 - 4 R 7 S m a l l s o l u t i o n s i z e

4 . 7 H M u r a t a L Q H 3 C 4 R 7 M 2 4 S m a l l s o l u t i o n s i z e

H i g h e f f i c i e n c y T P S 6 1 0 4 1 1 0 H M u r a t a L Q H 3 C 1 0 0 K 2 4

S m a l l s o l u t i o n s i z e

T h e o u t p u t v o l t a g e i s c a l c u l a t e d a s :

F o r b a t t e r y p o w e r e d a p p l i c a t i o n s , a h i g h i m p e d a n c e v o l t a g e d i v i d e r s h o u l d b e u s e d w i t h a t y p i c a l v a l u e f o r R 2 o f 2 0 0 k a n d a m a x i m u m v a l u e f o r R 1 o f 2 . 2 M . S m a l l e r v a l u e s m i g h t b e u s e d t o r e d u c e t h e n o i s e s e n s i t i v i t y o f t h e f e e d b a c k p i n .

A f e e d - f o r w a r d c a p a c i t o r a c r o s s t h e u p p e r f e e d b a c k r e s i s t o r R 1 i s r e q u i r e d t o p r o v i d e s u f f i c i e n t o v e r d r i v e f o r t h e e r r o r c o m p a r a t o r . W i t h o u t a f e e d - f o r w a r d c a p a c i t o r , o r o n e w h o s e v a l u e i s t o o s m a l l , t h e T P S 6 1 0 4 0 / 4 1 s h o w s d o u b l e p u l s e s o r a p u l s e b u r s t i n s t e a d o f s i n g l e p u l s e s a t t h e s w i t c h n o d e ( S W ) , c a u s i n g h i g h e r o u t p u t v o l t a g e

r i p p l e . I f t h i s h i g h e r o u t p u t v o l t a g e r i p p l e i s a c c e p t a b l e , t h e f e e d - f o r w a r d c a p a c i t o r c a n b e l e f t o u t .

T h e l o w e r t h e s w i t c h i n g f r e q u e n c y o f t h e c o n v e r t e r , t h e l a r g e r t h e f e e d - f o r w a r d c a p a c i t o r v a l u e r e q u i r e d . A g o o d s t a r t i n g p o i n t i s t o u s e a 1 0 - p F f e e d - f o r w a r d c a p a c i t o r . A s a f i r s t e s t i m a t i o n , t h e r e q u i r e d v a l u e f o r t h e f e e d - f o r w a r d c a p a c i t o r a t t h e o p e r a t i o n p o i n t c a n a l s o b e c a l c u l a t e d u s i n g t h e f o l l o w i n g f o r m u l a :

W h e r e :

R 1 = U p p e r r e s i s t o r o f v o l t a g e d i v i d e r

f S = S w i t c h i n g f r e q u e n c y o f t h e c o n v e r t e r a t t h e n o m i n a l l o a d c u r r e n t ( s e e t h e p r e v i o u s s e c t i o n f o r c a l c u l a t i n g t h e s w i t c h i n g f r e q u e n c y )

CF F = C h o o s e a v a l u e t h a t c o m e s c l o s e s t t o t h e r e s u l t o f t h e c a l c u l a t i o n

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L I N E A N D L O A D R E G U L A T I O N

O U T P U T C A P A C I T O R S E L E C T I O N

DVout+IoutCout

1fS(Iout)

IP L

Vout) VdVin) I

P ESR

( 7 )


T h e l a r g e r t h e f e e d - f o r w a r d c a p a c i t o r t h e w o r s e t h e l i n e r e g u l a t i o n o f t h e d e v i c e . T h e r e f o r e , w h e n c o n c e r n f o r l i n e r e g u l a t i o n i s p a r a m o u n t , t h e s e l e c t e d f e e d - f o r w a r d c a p a c i t o r s h o u l d b e a s s m a l l a s p o s s i b l e . S e e t h e n e x t s e c t i o n f o r m o r e i n f o r m a t i o n a b o u t l i n e a n d l o a d r e g u l a t i o n .

T h e l i n e r e g u l a t i o n o f t h e T P S 6 1 0 4 0 / 4 1 d e p e n d s o n t h e v o l t a g e r i p p l e o n t h e f e e d b a c k p i n . U s u a l l y a 5 0 - m V

p e a k - t o - p e a k v o l t a g e r i p p l e o n t h e f e e d b a c k p i n F B g i v e s g o o d r e s u l t s .

S o m e a p p l i c a t i o n s r e q u i r e a v e r y t i g h t l i n e r e g u l a t i o n a n d c a n o n l y a l l o w a s m a l l c h a n g e i n o u t p u t v o l t a g e o v e r a c e r t a i n i n p u t v o l t a g e r a n g e . I f n o f e e d - f e e d f o r w a r d f o r w a r d c a p a c i t o r C F F i s u s e d a c r o s s t h e u p p e r r e s i s t o r o f t h e v o l t a g e f e e d b a c k d i v i d e r , t h e d e v i c e h a s t h e b e s t l i n e r e g u l a t i o n . W i t h o u t t h e f e e d - f o r w a r d c a p a c i t o r t h e o u t p u t v o l t a g e r i p p l e i s h i g h e r b e c a u s e t h e T P S 6 1 0 4 0 / 4 1 s h o w s o u t p u t v o l t a g e b u r s t s i n s t e a d o f s i n g l e p u l s e s o n t h e s w i t c h p i n ( S W ) , i n c r e a s i n g t h e o u t p u t v o l t a g e r i p p l e . I n c r e a s i n g t h e o u t p u t c a p a c i t o r v a l u e r e d u c e s t h e o u t p u t v o l t a g e r i p p l e .

I f a l a r g e r o u t p u t c a p a c i t o r v a l u e i s n o t a n o p t i o n , a f e e d - f o r w a r d c a p a c i t o r C F F c a n b e u s e d a s d e s c r i b e d i n t h e p r e v i o u s s e c t i o n . T h e u s e o f a f e e d - f o r w a r d c a p a c i t o r i n c r e a s e s t h e a m o u n t o f v o l t a g e r i p p l e p r e s e n t o n t h e f e e d b a c k p i n ( F B ) . T h e g r e a t e r t h e v o l t a g e r i p p l e o n t h e f e e d b a c k p i n ( 5 0 m V ) , t h e w o r s e t h e l i n e r e g u l a t i o n . T h e r e a r e t w o w a y s t o i m p r o v e t h e l i n e r e g u l a t i o n f u r t h e r :

1 . U s e a s m a l l e r i n d u c t o r v a l u e t o i n c r e a s e t h e s w i t c h i n g f r e q u e n c y w h i c h w i l l l o w e r t h e o u t p u t v o l t a g e r i p p l e ,

a s w e l l a s t h e v o l t a g e r i p p l e o n t h e f e e d b a c k p i n . 2 . A d d a s m a l l c a p a c i t o r f r o m t h e f e e d b a c k p i n ( F B ) t o g r o u n d t o r e d u c e t h e v o l t a g e r i p p l e o n t h e f e e d b a c k p i n

d o w n t o 5 0 m V a g a i n . A s a s t a r t i n g p o i n t , t h e s a m e c a p a c i t o r v a l u e a s s e l e c t e d f o r t h e f e e d - f o r w a r d c a p a c i t o r C F F c a n b e u s e d .

F o r b e s t o u t p u t v o l t a g e f i l t e r i n g , a l o w E S R o u t p u t c a p a c i t o r i s r e c o m m e n d e d . C e r a m i c c a p a c i t o r s h a v e a l o w E S R v a l u e b u t t a n t a l u m c a p a c i t o r s c a n b e u s e d a s w e l l , d e p e n d i n g o n t h e a p p l i c a t i o n .

A s s u m i n g t h e c o n v e r t e r d o e s n o t s h o w d o u b l e p u l s e s o r p u l s e b u r s t s o n t h e s w i t c h n o d e ( S W ) , t h e o u t p u t v o l t a g e r i p p l e c a n b e c a l c u l a t e d a s :

W h e r e :

IP = P e a k c u r r e n t a s d e s c r i b e d i n t h e p r e v i o u s P e a k C u r r e n t C o n t r o l s e c t i o n


Io u t = N o m i n a l l o a d c u r r e n t

f S ( I o u t) = S w i t c h i n g f r e q u e n c y a t t h e n o m i n a l l o a d c u r r e n t a s c a l c u l a t e d p r e v i o u s l y

V d = R e c t i f i e r d i o d e f o r w a r d v o l t a g e ( t y p i c a l l y 0 . 3 V )

Co u t = S e l e c t e d o u t p u t c a p a c i t o r

E S R = O u t p u t c a p a c i t o r E S R v a l u e

R e f e r t o T a b l e 2 a n d t y p i c a l a p p l i c a t i o n s s e c t i o n f o r c h o o s i n g t h e o u t p u t c a p a c i t o r .

T a b l e 2 . R e c o m m e n d e d I n p u t a n d O u t p u t C a p a c i t o r s

D E V I C E C A P A C I T O R V O L T A G E R A T I N G C O M P O N E N T S U P P L I E R C O M M E N T S

4 . 7 F / X 5 R / 0 8 0 5 6 . 3 V T a y o Y u d e n J M K 2 1 2 B Y 4 7 5 M G C I N / C O U T

1 0 F / X 5 R / 0 8 0 5 6 . 3 V T a y o Y u d e n J M K 2 1 2 B J 1 0 6 M G C I N / C O U T

T P S 6 1 0 4 0 / 4 1 1 . 0 F / X 7 R / 1 2 0 6 2 5 V T a y o Y u d e n T M K 3 1 6 B J 1 0 5 K L C O U T

1 . 0 F / X 5 R / 1 2 0 6 3 5 V T a y o Y u d e n G M K 3 1 6 B J 1 0 5 K L C O U T

4 . 7 F / X 5 R / 1 2 1 0 2 5 V T a y o Y u d e n T M K 3 2 5 B J 4 7 5 M G C O U T

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I N P U T C A P A C I T O R S E L E C T I O N

D I O D E S E L E C T I O N

L A Y O U T C O N S I D E R A T I O N S

VIN SW

FB

EN GND

L1 D1

R1

R2

CFF

CO

VO

VIN

CIN

T P S 6 1 0 4 0 - Q 1 T P S 6 1 0 4 1 - Q 1

S G L S 2 7 6 J A N U A R Y 2 0 0 5

F o r g o o d i n p u t v o l t a g e f i l t e r i n g , l o w E S R c e r a m i c c a p a c i t o r s a r e r e c o m m e n d e d . A 4 . 7 - F c e r a m i c i n p u t c a p a c i t o r i s s u f f i c i e n t f o r m o s t o f t h e a p p l i c a t i o n s . F o r b e t t e r i n p u t v o l t a g e f i l t e r i n g t h i s v a l u e c a n b e i n c r e a s e d . S e e T a b l e 2 a n d t h e T y p i c a l A p p l i c a t i o n s s e c t i o n f o r i n p u t c a p a c i t o r r e c o m m e n d a t i o n s .

T o a c h i e v e h i g h e f f i c i e n c y a S c h o t t k y d i o d e s h o u l d b e u s e d . T h e c u r r e n t r a t i n g o f t h e d i o d e s h o u l d m e e t t h e p e a k c u r r e n t r a t i n g o f t h e c o n v e r t e r a s i t i s c a l c u l a t e d i n t h e s e c t i o n p e a k c u r r e n t c o n t r o l . U s e t h e m a x i m u m v a l u e f o r I L I M f o r t h i s c a l c u l a t i o n . S e e T a b l e 3 a n d t h e T y p i c a l A p p l i c a t i o n s s e c t i o n f o r t h e s e l e c t i o n o f t h e S c h o t t k y d i o d e .

T a b l e 3 . R e c o m m e n d e d S c h o t t k y D i o d e f o r T y p i c a l L C D B i a s S u p p l y ( s e e F i g u r e 1 5 )

D E V I C E R E V E R S E V O L T A G E C O M P O N E N T S U P P L I E R C O M M E N T S

3 0 V O N S e m i c o n d u c t o r M B R 0 5 3 0

2 0 V O N S e m i c o n d u c t o r M B R 0 5 2 0 T P S 6 1 0 4 0 / 4 1

2 0 V O N S e m i c o n d u c t o r M B R M 1 2 0 L H i g h e f f i c i e n c y

3 0 V T o s h i b a C R S 0 2

T y p i c a l f o r a l l s w i t c h i n g p o w e r s u p p l i e s , t h e l a y o u t i s a n i m p o r t a n t s t e p i n t h e d e s i g n ; e s p e c i a l l y a t h i g h p e a k c u r r e n t s a n d s w i t c h i n g f r e q u e n c i e s . I f t h e l a y o u t i s n o t c a r e f u l l y d o n e , t h e r e g u l a t o r m i g h t s h o w n o i s e p r o b l e m s a n d d u t y c y c l e j i t t e r .

T h e i n p u t c a p a c i t o r s h o u l d b e p l a c e d a s c l o s e a s p o s s i b l e t o t h e i n p u t p i n f o r g o o d i n p u t v o l t a g e f i l t e r i n g . T h e i n d u c t o r a n d d i o d e s h o u l d b e p l a c e d a s c l o s e a s p o s s i b l e t o t h e s w i t c h p i n t o m i n i m i z e t h e n o i s e c o u p l i n g i n t o o t h e r c i r c u i t s . S i n c e t h e f e e d b a c k p i n a n d n e t w o r k i s a h i g h i m p e d a n c e c i r c u i t t h e f e e d b a c k n e t w o r k s h o u l d b e r o u t e d a w a y f r o m t h e i n d u c t o r . T h e f e e d b a c k p i n a n d f e e d b a c k n e t w o r k s h o u l d b e s h i e l d e d w i t h a g r o u n d p l a n e o r t r a c e t o m i n i m i z e n o i s e c o u p l i n g i n t o t h i s c i r c u i t .

W i d e t r a c e s s h o u l d b e u s e d f o r c o n n e c t i o n s i n b o l d a s s h o w n i n F i g u r e 1 5 . A s t a r g r o u n d c o n n e c t i o n o r g r o u n d p l a n e m i n i m i z e s g r o u n d s h i f t s a n d n o i s e .

F i g u r e 1 5 . L a y o u t D i a g r a m

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VIN SW

FB

EN GND

L1

10 H D1

R1

2.2 MW

R2

160 kW

CFF22 pF

C2

1 F

VOUT18 V

VIN1.8 V to 6 V

C1

4.7 F L1: Sumida CR32-100

D1: Motorola MBR0530

C1: Tayo Yuden JMK212BY475MG

C2: Tayo Yuden TMK316BJ105KL

TPS61040

VIN SW

FB

EN GND

L1

10 H D1

R1

2.2 MW

R2

160 kW

CFF22 pF

C2

1 F

VO

18 V

VIN

1.8 V to 6 V

C1

4.7 F DAC or Analog Voltage

0 V = 25 V1.233 V = 18 V

TPS61040

L1: Sumida CR32-100



C2: Tayo Yuden GMK316BJ105KL

VIN SW

FB

EN GND

L1

10 H D1

R1

2.2 MW

R2

160 kW

CFF22 pF

C2

1 F

VOUT18 V / 10 mA

VIN1.8 V to 6 V

C1

4.7 F

R3

200 kW

BC857C

C3

0.1 F(Optional)

L1: Sumida CR32-100

D1: Motorola MBR0530C1: Tayo Yuden JMK212BY475MG


TPS61040


F i g u r e 1 6 . L C D B i a s S u p p l y

F i g u r e 1 7 . L C D B i a s S u p p l y W i t h A d j u s t a b l e O u t p u t V o l t a g e

F i g u r e 1 8 . L C D B i a s S u p p l y W i t h L o a d D i s c o n n e c t

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VIN SW

FB

EN GND

L1

6.8

H

D1

R1

1.5 MW

R2

210 kW

CFF22 pF

C2

1 F

V1 = 10 V/15 mA

VIN = 2.7 V to 5 V

C1

4.7 F

C4

4.7 FC3

1 F

V2 = -10 V/15 mA

D2

D3

L1: Murata LQH4C6R8M04

D1, D2, D3: Motorola MBR0530


C2, C3, C4: Tayo Yuden EMK316BJ105KF

TPS61040

VIN SW

FB

EN GND

L1

6.8 H D1

R1

1.8 MW

R2

205 kW

CFF4.7 pF

C2

4.7 F

VO=12 V/35 mA

VIN 3.3 V

C1

10 F L1: Murata LQH4C6R8M04


C1: Tayo Yuden JMK212BJ106MG

C2: Tayo Yuden EMK316BJ475ML

TPS61040

VIN SW

FB

EN GND

3.3 H D1

C2

4.7 F

5 V/45 mA

1.8 V to 4 V

C1

4.7 F

TPS61040



C1, C2: Tayo Yuden JMK212BY475MG

CFF3.3 pFR1

620 kW

R2

200 kW

T P S 6 1 0 4 0 - Q 1 T P S 6 1 0 4 1 - Q 1

S G L S 2 7 6 J A N U A R Y 2 0 0 5

F i g u r e 1 9 . P o s i t i v e a n d N e g a t i v e O u t p u t L C D B i a s S u p p l y

F i g u r e 2 0 . S t a n d a r d 3 . 3 - V t o 1 2 - V S u p p l y

F i g u r e 2 1 . D u a l B a t t e r y C e l l t o 5 V / 5 0 - m A C o n v e r s i o n E f f i c i e n c y A p r o x . E q u a l s 8 4 % a t V I N = 2 . 4 V t o V O = 5 V / 4 5 m A

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VIN SW

FB

EN GND

L1

10 H D1

C2

1 F

C1

4.7 F

RS82

VCC = 2.7 V to 6 V

PWM

100 Hz to 500 Hz

D2

24 V

(Optional)

L1: Murata LQH4C100K04




VIN SW

FB

EN GND

L1

10 H

D1

MBRM120L

C2

100 nF

C1

4.7 F

RS110 W

VCC = 2.7 V to 6 V

R1

120 kW

R2 160 kW

Analog Brightness Control

3.3 V Led Off

0 V Iled = 20 mA

D2

24 V(Optional)




C2: Standard Ceramic Capacitor


F i g u r e 2 2 . W h i t e L E D S u p p l y W i t h A d j u s t a b l e B r i g h t n e s s C o n t r o l U s i n g a P W M S i g n a l o n t h e E n a b l e P i n E f f i c i e n c y A p r o x . E q u a l s 8 6 % a t V I N = 3 V , I L E D = 1 5 m A

A . A s m a l l e r o u t p u t c a p a c i t o r v a l u e f o r C 2 c a u s e s a l a r g e r L E D r i p p l e .

F i g u r e 2 3 . W h i t e L E D S u p p l y W i t h A d j u s t a b l e B r i g h t n e s s C o n t r o l U s i n g a n A n a l o g S i g n a l o n t h e F e e d b a c k P i n

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