Datasheet

4
FB
VIN
AGND
5
6
3
2
1
VIN
C
1
DIM
C
2
L
1
PGND
PGND
C
3
V
O
SW
L
2
D
1
R
1
LED
1
V
OUT
D =
¨
©
§
(V
IN
x K)+
V
OUT
¸
¹
·
V
OUT
V
IN
=
1 - D
D
x K
¸
¹
·
¨
©
§
1
+ +
¸
¹
·
¨
©
§
R
L1
¸
¸
¹
·
¨
¨
©
§
D
2
D
2
'
¨
©
§
R
ON
¸
¹
·
¸
¸
¹
·
¨
¨
©
§
D
D
2
'
1+
+
¸
¸
¹
·
R
L2
V
D
V
OUT
¨
¨
©
§
K=
R
OUT
R
OUT
R
OUT
¨
¨
¨
¨
¨
¨
©
§
¸
¸
¸
¸
¸
¸
¹
·
V
OUT
R
OUT
=
I
LED
LM3410, LM3410Q
SNVS541G –OCTOBER 2007–REVISED MAY 2013 www.ti.com
(66)
Therefore:
(67)
One can see that all variables are known except for the duty cycle (D). A quadratic equation is needed to solve
for D. A less accurate method of determining the duty cycle is to assume efficiency, and calculate the duty cycle.
(68)
(69)
Table 7. Efficiencies for Typical SEPIC Applications
V
IN
2.7V V
IN
3.3V V
IN
5V
V
OUT
3.1V V
OUT
3.1V V
OUT
3.1V
I
IN
770mA I
IN
600mA I
IN
375mA
I
LED
500mA I
LED
500mA I
LED
500mA
η 75% η 80% η 83%
SEPIC Converter PCB Layout
The layout guidelines described for the LM3410 Boost-Converter are applicable to the SEPIC OLED Converter.
Figure 28 is a proper PCB layout for a SEPIC Converter.
Figure 28. HB/OLED SEPIC PCB Layout
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