S101-05200183B
| Model | S101-05200183B |
| Description | DC-DC Regulated Power Supply Module, 2 Output, Hybrid, ROHS COMPLIANT-10 |
| PDF file | Total 6 pages (File size: 210K) |
| Chip Manufacturer | MURATA |
S101-084-S101-00
5.0v Input, 1.5 to 3.3v Output @ 7A
External Capacitance for SIP Products
A ll S IP p r o d u c ts r e q u ir e e x te r n a l c a p a c ita n c e to b e p la c e d o n th e s y s te m b o a r d th a t th e S IP w ill b e d e s ig n e d
in to . T h is a p p lic a tio n n o te is a n a tte m p t to e x p la in h o w to tr a n s la te d a ta s h e e t in f o r m a tio n a n d a p p ly it to a
s y s te m le v e l b o a r d d e s ig n .
IN P U T C A P A C IT A N C E
A lth o u g h in p u t c a p a c ita n c e v a lu e is n o t c r itic a l, th e in p u t c a p a c ito r s m u s t b e c a p a b le o f s to r in g f a ir ly la r g e
a m o u n ts o f e n e r g y . T h is m e a n s , f o r e x a m p le , s m a ll c e r a m ic c a p a c ito r s w o u ld b e in a p p r o p r ia te . T h e p r im a r y
c r ite r ia , th o u g h , f o r c h o o s in g th e in p u t c a p a c ito r s is A C r ip p le c u r r e n t r a tin g . T h e S IP d a ta s h e e t c o n ta in s a
c h a r t s h o w in g r ip p le c u r r e n t v s . o u tp u t c u r r e n t ( o r o u tp u t p o w e r ) . T h e s y s te m d e s ig n e r d e te r m in e s th e
m a x im u m S IP o u tp u t c u r r e n t r e q u ir e d f r o m th e S IP . B a s e d o n th a t n u m b e r , th e c h a r t w ill s h o w a
c o r r e s p o n d in g r ip p le c u r r e n t r a tin g th e d e s ig n e r n e e d s to p la n fo r w h e n c h o o s in g in p u t c a p a c ito r s .
E x a m p le u s in g S IP S 1 0 1 :
T h e d e s ig n e r k n o w s th e S 1 0 1 is in te n d e d to p r o v id e 2 .5 V a t m a x im u m 5 A . U s in g th e S 1 0 1 d a ta s h e e t
c h a r t, th is c o r r e s p o n d s w ith 4 A o f r ip p le c u r r e n t. A ls o k n o w n is th a t th e c a p a c ito r th e d e s ig n e r h o p e s
to u s e h a s a r ip p le c u r r e n t r a tin g o f 2 .2 A . T h e r e f o r e , th e d e s ig n e r m u s t u s e tw o o f th e c h o s e n
c a p a c ito r s in p a r a lle l fo r a to ta l r ip p le c u r r e n t c a p a b ility o f 4 .4 A - w h ic h w ill b e s u f f ic ie n t f o r th e 4 A
r e q u ir e m e n t.
O U T P U T C A P A C IT A N C E
T h e o n ly r e q u ir e m e n t fo r c a p a c ita n c e v a lu e is f o r b a s ic c ir c u it s ta b ility o f th e S IP . T h a t v a lu e is s p e c if ie d o n
th e S IP d a ta s h e e t— u s u a lly 1 5 0
μ
F . T h e o th e r c o n s id e r a tio n f o r o u tp u t c a p a c ita n c e is th e to ta l e f fe c tiv e E S R
( E q u iv a le n t S e r ie s R e s is ta n c e ) . A s w ith r ip p le c u r r e n t, e v e r y c a p a c ito r h a s a s p e c if ie d E S R . W h e n u s in g
m u ltip le c a p a c ito r s in p a r a lle l, th is E S R is a d d e d e x a c tly lik e p a r a lle l r e s is to r s . T h e r e fo r e , m o r e c a p a c ito r s
m e a n le s s E S R . T h e S IP d a ta s h e e t s p e c if ie s a m a x im u m to ta l E S R n e c e s s a r y f o r o p tim u m S IP p e r f o r m a n c e .
T h e d e s ig n e r m a y a ls o c h o o s e to a d d m o r e c a p a c ita n c e to r e d u c e o u tp u t r ip p le a n d n o is e .
E x a m p le u s in g S IP S 1 0 1 :
T h e S 1 0 1 d a ta s h e e t s p e c if ie s a m a x im u m E S R o f 1 0 0 m
f o r o u tp u t c a p a c ita n c e . T h e s y s te m
d e s ig n e r w a n ts to u s e a c a p a c ito r w ith a s p e c if ie d E S R o f 1 3 0 m . S in c e 1 3 0 m
is m o r e th a n th e
n e e d e d 1 0 0 m , tw o c a p a c ito r s m u s t b e u s e d in p a r a lle l f o r a to ta l e ff e c tiv e E S R o f 6 5 m .
G e n e r a lly , g o o d , lo w E S R b u lk c a p a c ito r s w ill b e u s e d fo r b o th in p u t a n d o u tp u t c a p a c ita n c e s o th a t f e w e r
c a p a c ito r s a r e n e e d e d s in c e b o a r d r e a l e s ta te is u s u a lly a n im p o r ta n t f a c to r in to d a y 's d e s ig n s .
Impact on Output Voltage Ripple and Transient Response
If th e c u s to m e r’s a p p lic a tio n re q u ire s a v e r y lo w o u tp u t v o lta g e rip p le a n d / o r v e ry lo w o u tp u t v o lta g e o v e rs h o o t /
u n d e rs h o o t d u rin g tra n s ie n ts , th e n th e g u id e lin e s p re v io u s ly s h o w n n e e d to b e e x c e e d e d a n d g o o d la yo u t p ra c tic e s
b e c o m e m a n d a to ry.
B y u s in g fo u r 3 3 0
μ
F O S C O N c a p a c ito rs , e a c h h a vin g E S R = 1 7 m , th e o u tp u t v o lta g e rip p le c a n b e d e c re a s e d to
5 0 m V p k -p k o n a 1 .2 V o u tp u t S IP . A ls o d u rin g a tra n s ie n t lo a d c o n d itio n (lo a d c u rre n t s te p s fro m 2 0 % to 1 0 0 % a n d
b a c k , a t 2 A /
μ
s e c ) th e o u tp u t v o lta g e d o e s n o t o v e rs h o o t / u n d e rs h o o t m o re th a n 1 0 0 m V .
W h e n fa s t a n d d e e p tra n s ie n t lo a d s a re e x p e c te d , th e in p u t c a p a c ito r b e c o m e s im p o rta n t a s w e ll, e s p e c ia lly if th e S IP
m ig h t
is fa r fro m its in p u t v o lta g e s o u rc e . C a p a c ito rs h a v in g a s m u c h a s 2 0 0 0
μ
F a n d c o m b in e d E S R lo w e r th a n 2 0 m
be needed.
P ra c tic a l re s u lts h e a v ily d e p e n d o n p h ys ic a l la yo u t a n d s p e c ific lo a d c o n d itio n s . F o r c ritic a l a p p lic a tio n s th e c u s to m e r
is e n c o u ra g e d to c o n s u lt w ith th e m a n u fa c tu re r.
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other
technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without
notice.
© 2010 Murata Power Solutions, Inc.
www.murata-ps.com/locations
email: sales@murata-ps.com
29 Apr 2010 MDC_S101-084-S101-00.B01
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