LP3368 datasheet(7/8 Pages) POWER

7 / 8 page

LP3368-02

May. -2014

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Page 7 of 8

Preliminary Datasheet

LP3368

Brightness Control Using PWM

Dimming control can be achieved by applying a

PWM control signal to the EN1/2 pin for each

channel. The brightness of the white LEDs is

controlled by increasing and decreasing the duty

cycle of the PWM signal. While the operating

frequency range of the PWM control is from 60Hz to

700Hz, the recommended maximum brightness

frequency range of the PWM signal is from 200Hz to

500Hz. A repetition rate of at least 60Hz is required

to prevent flicker.

Application Information

The LP3368 charge pump circuit requires 3

capacitors: 4.7μF input, 2μF output and 2μF fly

capacitors are typically recommended. For the input

capacitor, a value of 10μF will help reduce input

voltage ripple for applications sensitive to ripple on

the battery voltage. All the capacitors should be

surface mount for low lead inductance necessary at

the 2MHz switching frequency of the LP3368 and to

obtain low ESR, which improves bypassing on the

input and output and improves output voltage drive

by reducing output resistance. The input and output

capacitors should be located as close to the VIN and

VOUT pins as possible to obtain best bypassing, and

the returns should be connected directly to the GND

pin under the LP3368. The fly capacitor should be

located as close to the C1* and C2* pins as possible.

LP3368 Arkusz danych(PDF) 7 Page - Lowpower Semiconductor inc