AL5802LP_7 datasheet(7/10 Pages) DIODES

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SBR is a registered trademark of Diodes Incorporated

AL5802LP-7

Document number: DS37549 Rev. 3 - 2

7 of 10

www.diodes.com

May 2015

AL5802LP-7

Application Information (cont.)

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 14. 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 16 is a typical response of LED current vs. PWM duty cycle on the EN pin.

-or-

Figure 14 Application Circuits for LED Driver with PWM Dimming Functionality

Figure 15 Typical LED Current Response vs. PWM Duty Cycle for

REXT = 13Ω at 400Hz PWM Frequency

To remove the potential of incorrect connection of the power supply

damaging the lamp’s LEDs, many systems use some form of reverse polarity

protection.

One solution for reverse input polarity protection is to simply use a diode with a low VF in-line with the driver/LED combination. The low VF of the

series connected diode increases the available voltage to the LED stack and dissipates less power. A circuit example is presented in Figure 16

using Diodes Inc. SBR

(Super Barrier Rectifier) technology. An SDM10U45LP (0.1A/45V) is shown, providing exceptionally low VF for its package

size of 1mm x 0.6mm, equivalent to an 0402 chip style package. Other reverse voltage ratings are also available in Diodes’ website such as the

SBR02U100LP (0.2A/100V) or SBR0220LP (0.2A/20V).

Automotive applications commonly use this method for reverse battery protection.

100

PWM DUTY CYCLE (%)

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