Zxsc400 1w/3w Buck Led Drivers

Diodes, Inc.

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appnote circuit ,Schematic
DN85
ZXSC400 1W/3W buck LED drivers
Ray Liu, Applications Engineer, Zetex Semiconductors
Description
In Figure 1, ZXSC400 is configured as a high efficiency buck LED driver. The target applications
are either 1W (350mA) or 3W (700mA) drivers for white LED driven from a 4 cell Battery or a 2
alkaline cell input for flashlights. The supply voltage for ZXSC400 reference design is:
V
IN
= 3.8V to 6V.
Parts lists for 1W and 3W design are shown in Table 1 and Table 2 respectively. Performance data
is measured based on two different LED's V
F
binning with 0.3V V
F
difference.
C3
V
IN
= 4V to 6V
L1
D1
C2
U1
V
CC
Stdn
V
DRIVE
V
FB
I
SENSE
Q1
R3
R2
C1
GND
R1
Figure 1
Schematic diagram
Issue 1 - August 2007
© Zetex Semiconductors plc 2007
1
www.zetex.com