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dc2345af
DEMO MANUAL DC2345A
I
LED
(A)
EFFICIENCY (%)
V
IN
(V)
60
0
100
70
3
0
10
20
30
40
50
75
80
90
85
95
0.5
1
2
1.5
2.5
EFFICIENCY
BOOST
BUCK
BUCK-BOOST
V
LED
= 25V
I
LED
= 2A
f
SW
= 400kHz
I
LED
5µs/DIV
I
L1
1A/DIV
I
LED
1A/DIV
INFINITE PERSIST
V
IN
= 24V
V
LED
= 25V
SPREAD SPECTRUM ON
1000:1 DIMMING: EXTERNAL PWM SOURCE, 120Hz
10µs/DIV
I
L1
1A/DIV
I
LED
1A/DIV
INFINITE PERSIST
V
IN
= 24V
V
LED
= 25V
SPREAD SPECTRUM ON
128:1 DIMMING: INTERNAL PWM DIMMING, 200Hz
QUICK START PROCEDURE
Figure 2. DC2345A Efficiency and LED Current Versus Input Voltage for 25V 2A LED Load.
Efficiency Peaks at 98% and Doesn’t Stray Far from That Peak, Ranging from 95% to 97%
Throughout the Typical 9V-16V Automotive Input Range. Also Shown, the LT8391 Peak
Inductor Current Limit Can Maintain Stable Output with Reduced Output Power at Low V
IN
.
Figure 3. Infinite-Persist Scope Traces Show PWM Dimming and SSFM Working Together for
Flicker-Free Brightness Control with Both Externally and Internally Generated PWM Dimming.
