LT3486_08 Datasheet, PDF (17/20 Pages) Linear Technology – Dual 1.3A White LED Step-Up Converters with Wide Dimming

LT3486
TYPICAL APPLICATIONS
5V to 16/16 White LEDs
16 LEDs
D5
C3
1µF
D3
5V
D6
C_IN
1µF
D4
C4
1µF
C1
0.1µF
L1
15µH
L2
15µH
C2
0.1µF
16 LEDs
25mA
PWM FREQ
200Hz
100k
C_OUT1
2.2µF
D1
SW1
OVP1
V_IN CTRL1
OFF ON SHDN
PWM1
FB1
V_C1
V_IN
LT3486
R_T
D2
SW2
OVP2
C_OUT2
2.2µF
CTRL2 V_IN
REF
PWM2
C_REF
0.1µF
FB2
V_C2
25mA
4.02k
63.4k
4.02k
22pF
4.7nF
Q1
4.7nF
Q2
PWM FREQ
200Hz
8.06Ω
C_IN: 6.3V, X5R OR X7R
C_OUT1, C_OUT2: 35V, X5R OR X7R
C1-C4: 50V, X5R OR X7R
C_REF: 6.3V, X5R OR X7R
8.06Ω
D1, D2: ZETEX ZLLS400
D3-D6: PHILIPS BAV99W
L1, L2: TOKO D53LC (TYPE A)
Q1, Q2: FAIRCHILD 2N7002
100k
3486 TA08a
LED Current and Efficiency vs PWM Duty Cycle
85
35
V_IN = 5V
80 ^{16/16 LEDs}
30
75
25
EFFICIENCY
70
20
65
15
LED CURRENT
60
10
55
5
50
0
0
20
40
60
80 100
PWM DUTY CYCLE (%)
3486 TA08b
I_LED
50mA/DIV
I_L
500mA/DIV
PWM Dimming Waveforms
PWM
5V/DIV
L = 15µH
1ms/DIV
PWM FREQ = 200Hz
3486 TA08c
3486fe
17