Datasheet

10
LTC1872B
LTC1872B 3-Cell White LED Driver
I
TH
/RUN
LTC1872B
10k
R1
0.27Ω
53.6Ω
L1
150µH
220pF
C1: TAIYO YUDEN CERAMIC EMK325BJ106MNT
C2: AVX TPSD156M035R0300
D0: MOTOROLA MBR0540
D1-D7: CMD333UWC
GND
V
FB
5
4
6
1872B TA04
1
2
3
NGATE
V
IN
SENSE
–
C1
10µF
10V
V
OUT
≈ 28.8V
(WITH 8 LEDs)
C2
15µF
35V
+
C3
0.1µF
CERAMIC
M1
D0
1 TO 8
WHITE
LEDs
15mA
D1
D2
•
•
•
D8
AA
AA
AA
V
IN
= 3 AA CELLS ≈ 2.7V TO 4.8V
L1: COILCRAFT DO1608C-154
M1: Si9804
R1: DALE 0.25W
APPLICATIONS INFORMATION
WUU
U
Figure 6. LTC1872B Layout Diagram (See PC Board Layout Checklist)
L1
M1
BOLD LINES INDICATE HIGH CURRENT PATHS
D1
R
S
V
OUT
V
IN
1872B F06
0.1µF
C
ITH
R
ITH
R2
R1
C
IN
+
I
TH
/RUN
LTC1872B
GND
V
FB
6
5
4
1
2
3
NGATE
V
IN
SENSE
–
C
OUT
+
TYPICAL APPLICATIO S
U