Datasheet
I
CSH
(éA)
I
LED
(A)
1.0
0.8
0.6
0.4
0.2
0.0
0 20 40 60 80 100
DUTY CYCLE (%)
I
LED
(A)
25 kHz
1 kHz
100806040200
0.8
0.2
0.4
0.6
0.8
1.0
V
IN
(V)
I
LED
(A)
1.010
1.005
1.000
0.995
0.990
5 10 15 20 25 30
V
IN
(V)
I
LED
(A)
1.02
1.01
1.00
0.99
0.98
0 16 32 48 64 80
V
IN
(V)
EFFICIENCY (%)
100
95
90
85
80
10 15 20 25 30
V
IN
(V)
EFFICIENCY (%)
100
95
90
85
80
75
70
0 16 32 48 64 80
LM3421, LM3421-Q1
LM3423, LM3423-Q1
SNVS574E –JULY 2008–REVISED MAY 2013
www.ti.com
Typical Performance Characteristics
T
A
=+25°C and V
IN
= 14V unless otherwise specified
Boost Efficiency vs. Input Voltage Buck-Boost Efficiency vs. Input Voltage
V
O
= 32V (9 LEDs)
(1)
V
O
= 21V (6 LEDs)
(2)
Figure 4. Figure 5.
Boost LED Current vs. Input Voltage Buck-Boost LED Current vs. Input Voltage
V
O
= 32V (9 LEDs)
(1)
V
O
= 21V (6 LEDs)
(2)
Figure 6. Figure 7.
Analog Dimming PWM Dimming
V
O
= 21V (6 LEDs); V
IN
= 24V
(2)
V
O
= 32V (9 LEDs); V
IN
= 24V
(1)
Figure 8. Figure 9.
(1) The measurements were made using the standard boost evaluation board from SNVA416.
(2) The measurements were made using the standard buck-boost evaluation board from .
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