Diodes AL5802 - Manual (Page 8)

AL5802
Document number: DS35516 Rev. 9 - 2
8 of 11
www.diodes.com
March 2014
© Diodes Incorporated
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AL5802
PWM dimming can be achieved by driving the EN pin. An external open-collector NPN transistor or open-drain N-channel MOSFET can be used
to drive the EN pin as shown in Figure 16. Dimming is achieved by turning the LEDs ON and OFF for a portion of a single cycle. The PWM
signal can be provided by a micro-controller or analog circuitry. Figure 17 is a typical response of LED current vs. PWM duty cycle on the EN pin.
-or-
Fig. 16 Application Circuits for LED Driver with PWM Dimming Functionality
Fig. 17 Typical LED current response vs. PWM duty cycle for
R
EXT
= 13Ω at 400Hz PWM frequency
0
10
20
40 60 80 100
L
E
D C
U
RRENT
(
m
A)
PWM DUTY CYCLE (%)
20 0
30
40
50
60