V
IN
SW
FB
EN
GND
L1
10
µ
H
D1
C2
1
µ
F
C1
4.7
µ
F
R
S
82
Ω
V
CC
= 2.7 V to 6 V
PWM
100 Hz to 500 Hz
D2
24 V
(Optional)
L1:
Murata LQH4C100K04
D1:
Motorola MBR0530
C1:
Tayo Yuden JMK212BY475MG
C2:
Tayo Yuden TMK316BJ105KL
V
IN
SW
FB
EN
GND
L1
10
µ
H
D1
MBRM120L
C2
100 nF
(See
Note A)
C1
4.7
µ
F
R
S
110
Ω
V
CC
= 2.7 V to 6 V
R1
120 k
Ω
R2
160 k
Ω
Analog Brightness Control
3.3 V
≅
Led Off
0 V
≅
Iled = 20 mA
D2
24 V
(Optional)
L1:
Murata LQH4C3R3M04
D1:
Motorola MBR0530
C1:
Tayo Yuden JMK212BY475MG
C2:
Standard Ceramic Capacitor
TPS61040
TPS61041
SLVS413F – OCTOBER 2002 – REVISED DECEMBER 2010
www.ti.com
Figure 22. White LED Supply With Adjustable Brightness Control
Using a PWM Signal on the Enable Pin, Efficiency Approx. Equals 86% at V
IN
= 3 V, I
LED
= 15 mA
A.
A smaller output capacitor value for C2 causes a larger LED ripple.
Figure 23. White LED Supply With Adjustable Brightness Control
Using an Analog Signal on the Feedback Pin
16
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