R1225N Datasheet, PDF (8/31 Pages) RICOH electronics devices division – PWM/VFM step-down DC/DC Converter

R1225N
• Discontinuous Conduction Mode and Continuous Conduction Mode
7KH PD[LPXP YDOXH ,/PD[ DQG WKH PLQLPXP YDOXH ,/PLQ FXUUHQW ZKLFK IORZ WKURXJK WKH LQGXFWRU LV WKH VDPH
DV WKRVH ZKHQ /[ 7U WXUQV RQ DQG ZKHQ LW WXUQV RII
7KH GLIIHUHQFH EHWZHHQ ,/PD[ DQG ,/PLQ ZKLFK LV UHSUHVHQWHG E\ ∆,
∆, ,/PD[,/PLQ 9287×WRSHQ/ 9,19287 ×WRQ/ (TXDWLRQ 
:KHUH 7 IRVF WRQ WRII
GXW\ WRQ7× WRQ×IRVF×
WRSHQ ≤ WRII
,Q (TXDWLRQ  9287×WRSHQ/ DQG 9,19287 ×WRQ/ DUH UHVSHFWLYHO\ VKRZQ WKH FKDQJH RI WKH FXUUHQW DW 21 DQG WKH
FKDQJH RI WKH FXUUHQW DW 2))
:KHQ WKH RXWSXW FXUUHQW ,287 LV UHODWLYHO\ VPDOO WRSHQ  WRII DV LOOXVWUDWHG LQ WKH DERYH GLDJUDP ,Q WKLV FDVH WKH
HQHUJ\ LV FKDUJHG LQ WKH LQGXFWRU GXULQJ WKH WLPH SHULRG RI WRQ DQG LV GLVFKDUJHG LQ LWV HQWLUHO\ GXULQJ WKH WLPH SHULRG
RI WRII WKHUHIRUH ,/PLQ EHFRPHV WR ]HUR ,/PLQ   :KHQ ,287 LV JUDGXDOO\ LQFUHDVHG HYHQWXDOO\ WRSHQ EHFRPHV WR
WRII WRSHQ WRII DQG ZKHQ ,287 LV IXUWKHU LQFUHDVHG ,/PLQ EHFRPHV ODUJHU WKDQ ]HUR ,/PLQ!  7KH IRUPHU PRGH LV
UHIHUUHG WR DV WKH GLVFRQWLQXRXV PRGH DQG WKH ODWWHU PRGH LV UHIHUUHG WR DV FRQWLQXRXV PRGH
,Q WKH FRQWLQXRXV PRGH ZKHQ (TXDWLRQ  LV VROYHG IRU WRQ DQG DVVXPHG WKDW WKH VROXWLRQ LV WRQF
WRQF 7×92879,1 (TXDWLRQ 
:KHQ WRQWRQF WKH PRGH LV WKH GLVFRQWLQXRXV PRGH DQG ZKHQ WRQ WRQF WKH PRGH LV WKH FRQWLQXRXV PRGH
8