PWM/VFM step-down DC/DC Converter
51 6(5,(6
NO. EA-097-0212
OUTLINE
7KH 51 6HULHV DUH &026EDVHG 3:0 VWHSGRZQ '&'& &RQYHUWHU FRQWUROOHUV ZLWK ORZ VXSSO\ FXUUHQW
(DFK RI WKHVH ,&V FRQVLVWV RI DQ RVFLOODWRU D 3:0 FRQWURO FLUFXLW D UHIHUHQFH YROWDJH XQLW DQ HUURU DPSOLILHU D VRIW
VWDUW FLUFXLW D ODWFKW\SH SURWHFWLRQ FLUFXLW D 3:09)0 DOWHUQDWLYH FLUFXLW D FKLS HQDEOH FLUFXLW D SKDVH FRPSHQVD
WLRQ FLUFXLW DQG DQ LQSXW YROWDJH GHWHFW FLUFXLW )XUWKHU SURWHFWLRQ FLUFXLW GHOD\ WLPH DGMXVWHU FLUFXLW DQG UHVLVWRUV IRU
YROWDJH GHWHFWLRQ DUH LQFOXGHG $ ORZ ULSSOH KLJK HIILFLHQF\ VWHSGRZQ '&'& FRQYHUWHU FDQ EH HDVLO\ FRPSRVHG RI
WKLV ,& ZLWK VRPH H[WHUQDO FRPSRQHQWV RU D SRZHUWUDQVLVWRU DQ LQGXFWRU D GLRGH DQG FDSDFLWRUV
:LWK D 3:09)0 DOWHUQDWLYH FLUFXLW ZKHQ WKH ORDG FXUUHQW LV VPDOO WKH RSHUDWLRQ LV DXWRPDWLFDOO\ VZLWFKLQJ LQWR WKH
9)0 RVFLOODWRU IURP 3:0 RVFLOODWRU WKHUHIRUH WKH HIILFLHQF\ DW VPDOO ORDG FXUUHQW LV LPSURYHG 7KH 51[[[&'.
W\SHV ZKLFK DUH ZLWKRXW D 3:09)0 DOWHUQDWLYH FLUFXLW DUH DOVR DYDLODEOH
,I WKH WHUP RI PD[LPXP GXW\ F\FOH NHHSV RQ D FHUWDLQ WLPH WKH HPEHGGHG SURWHFWLRQ FLUFXLW ZRUNV ,W LV ODWFKW\SH
SURWHFWLRQ FLUFXLW DQG LW ZRUNV WR ODWFK DQ H[WHUQDO 3RZHU 026)(7 ZLWK NHHSLQJ LW RII 7R UHOHDVH WKH FRQGLWLRQ RI
SURWHFWLRQ DIWHU GLVDEOH WKLV ,& ZLWK D FKLS HQDEOH FLUFXLW HQDEOH LW DJDLQ RU UHVWDUW WKLV ,& ZLWK SRZHURQ 'HOD\ 7LPH
IRU SURWHFWLRQ FLUFXLW LV DGMXVWDEOH ZLWK DQ H[WHUQDO FDSDFLWRU :LWK D EXLOWLQ 89/2 IXQFWLRQ ZKHQ WKH LQSXW YROWDJH LV
89/2 WKUHVKROG RU OHVV WKLV ,& NHHSV VWDQGE\ VWDWH DQG VDYHV LWV FRQVXPSWLRQ FXUUHQW DQG DYRLGV PLVVRSHUDWLRQ
)XUWKHU LI WKH VHW RXWSXW YROWDJH LV HTXDO RU PRUH WKDQ 9 ZLWK D EXLOWLQ VWDUWXS IXQFWLRQ DW WKH SRZHURQ PRPHQW
XQWLO WKH LQSXW YROWDJH EHFRPHV PRUH WKDQ WKH VHW RXWSXW YROWDJH '&'& RSHUDWLRQ LV KDOWHG DQG DYRLGV PLVVRSHUDWLRQ
FEATURES
•
:LGH 5DQJH RI ,QSXW 9ROWDJH9a9
•
%XLOWLQ 6RIWVWDUW )XQFWLRQ DQG /DWFKW\SH 3URWHFWLRQ )XQFWLRQ
•
7KUHH RSWLRQV RI 2VFLOODWRU )UHTXHQF\N+] N+] N+]
•
+LJK (IILFLHQF\ 7\S
•
2XWSXW 9ROWDJH6WHSZLVH 6HWWLQJ ZLWK D VWHS RI 9 LQ WKH UDQJH RI
9 a 9
•
6WDQGE\ &XUUHQW 7\S $
•
+LJK $FFXUDF\ 2XWSXW 9ROWDJH
•
/RZ 7HPSHUDWXUH'ULIW &RHIILFLHQW RI 2XWSXW 9ROWDJH7\S SSP&
APPLICATIONS
•
3RZHU VRXUFH IRU KDQGKHOG FRPPXQLFDWLRQ HTXLSPHQW FDPHUDV YLGHR LQVWUXPHQWV VXFK DV 9&5V FDPFRUGHUV
•
3RZHU VRXUFH IRU EDWWHU\SRZHUHG HTXLSPHQW
•
3RZHU VRXUFH IRU KRXVHKROG HOHFWULFDO DSSOLDQFHV
1
R1225N
BLOCK DIAGRAM
OSC
V
IN
Start
func
V
OUT
-
EXT
+
PWM/VFM
CONTROL
-
Amp
+
Vref
Soft Start
Protection
DLY
UVLO
Chip Enable
CE
+
-
Vref
GND
SELECTION GUIDE
,Q WKH 51 6HULHV WKH RXWSXW YROWDJH WKH RVFLOODWRU IUHTXHQF\ WKH RSWLRQDO IXQFWLRQ DQG WKH WDSLQJ W\SH IRU WKH
,&V FDQ EH VHOHFWHG DW WKH XVHU V UHTXHVW
7KH VHOHFWLRQ FDQ EH PDGH ZLWK GHVLJQDWLQJ WKH SDUW QXPEHU DV VKRZQ EHORZ
51[[[75
↑ ↑↑ ↑
D EF G
Code
D
E
Contents
6HWWLQJ 2XWSXW 9ROWDJH 9
287
6WHSZLVH VHWWLQJ ZLWK D VWHS RI 9 LQ WKH UDQJH RI 9 WR 9 LV SRVVLEOH
'HVLJQDWLRQ RI 2VFLOODWRU )UHTXHQF\
IL[HG
'HVLJQDWLRQ RI 2SWLRQDO )XQFWLRQ
$ N+] ZLWK D 3:09)0 DOWHUQDWLYH FLUFXLW
% N+] ZLWK D 3:09)0 DOWHUQDWLYH FLUFXLW
& N+] ZLWKRXW D 3:09)0 DOWHUQDWLYH FLUFXLW
' N+] ZLWKRXW D 3:09)0 DOWHUQDWLYH FLUFXLW
- N+] ZLWK D 3:09)0 DOWHUQDWLYH FLUFXLW
. N+] ZLWKRXW D 3:09)0 DOWHUQDWLYH FLUFXLW
'HVLJQDWLRQ RI 7DSLQJ 7\SH 5HIHU WR 7DSLQJ VSHFLILFDWLRQ
´75µ LV SUHVFULEHG DV D VWDQGDUG
←3DUW
1XPEHU
F
G
2
R1225N
PIN CONFIGURATION
SOT-23-6W
6
5
4
V
OUT
GND
(mark side)
CE
EXT
V
IN
DLY
1
2
3
PIN DESCRIPTION
Pin No.
Symbol
(;7
9
,1
'/<
&(
*1'
9
287
Description
([WHUQDO 7UDQVLVWRU 'ULYH 3LQ &026 2XWSXW 7\SH
3RZHU 6XSSO\ 3LQ
3LQ IRU 6HWWLQJ ([WHUQDO &DSDFLWRU IRU 3URWHFWLRQ &LUFXLW 'HOD\ 7LPH
&KLS (QDEOH 3LQ $FWLYH ´+µ
*URXQG 3LQ
3LQ IRU 0RQLWRULQJ 2XWSXW 9ROWDJH
ABSOLUTE MAXIMUM RATINGS
Symbol
9
,1
9
(;7
9
&(
9
287
9
'/<
,
(;7
,
'/<
3
'
7RSW
7VWJ
Item
9
,1
6XSSO\ 9ROWDJH
(;7 3LQ 2XWSXW 9ROWDJH
&( 3LQ ,QSXW 9ROWDJH
9
287
3LQ ,QSXW 9ROWDJH
9
'/<
3LQ ,QSXW 9ROWDJH
(;7 3LQ ,QGXFWRU 'ULYH 2XWSXW &XUUHQW
'/< 3LQ 2XWSXW &XUUHQW
3RZHU 'LVVLSDWLRQ
2SHUDWLQJ 7HPSHUDWXUH 5DQJH
6WRUDJH 7HPSHUDWXUH 5DQJH
Rating
a9
,1
a9
,1
a9
,1
a
a
a
Unit
9
9
9
9
9
P$
P$
P:
&
&
3
R1225N
ELECTRICAL CHARACTERISTICS
•
R1225Nxx2X (X=A/B/C/D/J/K)
Symbol
9
,1
9
287
∆9
287
∆7
Item
2SHUDWLQJ ,QSXW 9ROWDJH
6WHSGRZQ 2XWSXW 9ROWDJH
6WHSGRZQ 2XWSXW 9ROWDJH
7HPSHUDWXUH &RHIILFLHQW
9
,1
9
&(
9
6(7
9 ,
287
P$
:KHQ 9
6(7
≤
9 9
,1
9
&(
9
&
≤
7RSW
≤
&
9
,1
9
&(
9
6(7
9 ,
287
P$
:KHQ 9
6(7
≤
9 9
,1
9
&(
9
-. YHUVLRQ
$& YHUVLRQ
%' YHUVLRQ
&
≤
7RSW
≤
&
9
,1
9
&(
9
287
9
$%-. YHUVLRQ
& YHUVLRQ
' YHUVLRQ
9
,1
9 9
&(
9 9
287
9
9
,1
9 9
(;7
9 9
287
9
9
&(
9
9
,1
9 9
(;7
9 9
287
9
9
&(
9
9
,1
9 9
&(
9 9
'/<
9
9
,1
9
&(
9
287
9
9
,1
9
287
9 9
&(
9
9
,1
9 9
287
9
9
,1
9 9
287
9
$%- YHUVLRQ
9
,1
9
&(
9 WR 9 9
287
9
9
,1
9
&(
9 WR 9 9
287
9
9
,1
9
6(7
9 ,
287
P$
9
&(
9→9
6(7
9
9
,1
9
&(
9
6(7
9
9
287
9
6(7
9→9
9
89/2
9
9
PV
PV
Conditions
Min.
9
6(7
×
9
6(7
Typ.
7RSW &
Max.
9
6(7
×
Unit
9
9
SSP
&
IRVF
2VFLOODWRU )UHTXHQF\
N+]
∆I
26&
∆7
2VFLOODWRU )UHTXHQF\
7HPSHUDWXUH &RHIILFLHQW
6XSSO\ &XUUHQW
6WDQGE\ &XUUHQW
(;7 ´+µ 2XWSXW &XUUHQW
(;7 ´/ 2XWSXW &XUUHQW
µ
'/< VZLWFK FXUUHQW
&( ´+µ ,QSXW &XUUHQW
&( ´/ ,QSXW &XUUHQW
µ
&( ´+µ ,QSXW 9ROWDJH
&( ´/ ,QSXW 9ROWDJH
µ
2VFLOODWRU 0D[LPXP 'XW\ &\FOH
&
,
''
,VWE
,
(;7+
,
(;7/
,
6:
,
&(+
,
&(/
9
&(+
9
&(/
0D[GW\
$
$
P$
P$
P$
$
$
9
9
9)0GW\ 9)0 'XW\ &\FOH
9
89/2
9
89/2
7VWDUW
7SURW
89/2 9ROWDJH
89/2 5HOHDVH 9ROWDJH
'HOD\ 7LPH E\ 6RIW6WDUW IXQFWLRQ
'HOD\ 7LPH IRU SURWHFWLRQ FLUFXLW
4
R1225N
TYPICAL APPLICATION AND APPLICATION HINTS
L
PMOS
R1
C1
V
IN
CE
C2
EXT
GND
V
OUT
DLY
C4
SD
+
-
C3
LOAD
CE CONTROL
3026 +$70 +LWDFKL
6'
&
5
5%/ 5RKP
) &HUDPLF &DSDFLWRU
Ω
/ &50& 6XPLGD +
& ) 7DQWDOXP 7\SH
& ) &HUDPLF &DSDFLWRU
& Q) &HUDPLF &DSDFLWRU
:KHQ \RX XVH WKHVH ,&V FRQVLGHU WKH IROORZLQJ LVVXHV
•
$V VKRZQ LQ WKH EORFN GLDJUDP D SDUDVLWLF GLRGH LV IRUPHG LQ HDFK WHUPLQDO HDFK RI WKHVH GLRGHV LV QRW IRUPHG IRU
ORDG FXUUHQW WKHUHIRUH GR QRW XVH LW LQ VXFK D ZD\ :KHQ \RX FRQWURO WKH &( SLQ E\ DQRWKHU SRZHU VXSSO\ GR QRW
PDNH LWV ´+µ OHYHO PRUH WKDQ WKH YROWDJH OHYHO RI 9
,1
SLQ
•
7KH RSHUDWLRQ RI /DWFKW\SH SURWHFWLRQ FLUFXLW LV DV IROORZV
:KHQ WKH PD[LPXP GXW\ F\FOH FRQWLQXHV ORQJHU WKDQ WKH GHOD\ WLPH IRU SURWHFWLRQ FLUFXLW 5HIHU WR WKH (OHFWULFDO
&KDUDFWHULVWLFV WKH SURWHFWLRQ FLUFXLW ZRUNV WR VKXWGRZQ 3RZHU 026)(7 ZLWK ODWFKLQJ RSHUDWLRQ 7KHUHIRUH ZKHQ
DQ LQSXWRXWSXW YROWDJH GLIIHUHQFH LV VPDOO WKH SURWHFWLRQ FLUFXLW PD\ ZRUN ZLWK VPDOO ORDG FXUUHQW
7R UHOHDVH WKH SURWHFWLRQ RI ODWFK VWDWXV DIWHU GLVDEOH WKLV ,& ZLWK D FKLS HQDEOH FLUFXLW HQDEOH LW DJDLQ RU UHVWDUW WKLV
,& ZLWK SRZHURQ +RZHYHU LQ WKH FDVH RI UHVWDUWLQJ WKLV ,& ZLWK SRZHURQ DIWHU WKH SRZHU VXSSO\ LV WXUQHG RII LI D
FHUWDLQ DPRXQW RI FKDUJH UHPDLQV LQ &
,1
RU VRPH YROWDJH LV IRUFHG WR 9
,1
IURP &
,1
WKLV ,& PLJKW QRW EH UHVWDUWHG
HYHQ DIWHU SRZHURQ
•
6HW H[WHUQDO FRPSRQHQWV DV FORVH DV SRVVLEOH WR WKH ,& DQG PLQLPL]H WKH FRQQHFWLRQ EHWZHHQ WKH FRPSRQHQWV DQG
WKH ,& ,Q SDUWLFXODU D FDSDFLWRU VKRXOG EH FRQQHFWHG WR 9
287
SLQ ZLWK WKH PLQLPXP FRQQHFWLRQ 0DNH JURXQGLQJ
VXIILFLHQW DQG UHLQIRUFH VXSSO\LQJ /DUJH VZLWFKLQJ FXUUHQW IORZV WKURXJK WKH FRQQHFWLRQ RI SRZHU OLQH DQ LQGXFWRU
DQG WKH FRQQHFWLRQ RI 9
287
,I WKH LPSHGDQFH RI WKH FRQQHFWLRQ RI SRZHU VXSSO\ LV KLJK WKH YROWDJH OHYHO RI SRZHU
VXSSO\ RI WKH ,& IOXFWXDWHV ZLWK WKH VZLWFKLQJ FXUUHQW 7KLV PD\ FDXVH XQVWDEOH RSHUDWLRQ RI WKH ,&
5
京公网安备 11010802033920号
EEWORLD
