Diodes AP3605 Manuel d'utilisateur télécharger pdf (Page 10)

Jan. 2013 Rev. 1. 8 BCD Semiconductor Manufacturing Limited

4-Channel Charge Pump LED Driver with Current Balancing and Wide Range PWM Dimming AP3605

Data Sheet

Operation

Figure 18. AP3605 Typical Application Circuit with 4 WLEDs

Typical Application

The AP3605 is a high efficiency 1.5x fractional

charge pump with 4 channels of integrated current

source for white LED backlight applications. The

AP3605 consists of a linear regulator followed by a

1.5x charge pump which operates at 1MHz, 4

channels current source, a reference and other control

circuits. The linear regulator regulates its output

voltage to supply charge pump, guarantees that the

charge pump always operates at 5V output with 1.5x

mode. This configuration minimizes the output

ripple.

The charge pump can generate 80mA of output

current, so each of the 4 WLED can be powered with

up to 20mA of current. The maximum LED current is

set by a resistor connected to the ISET pin which

programs a reference current, then the reference

current is mirrored to set the LED current.

Applying a PWM signal to the EN pin can be used to

achieve LED brightness dimming. Integrated 2ms

standby function helps to enhance the dimming con-

trol. Detailed descriptions please see the related

application note.

1μF

OUT

1μF

C1+

OUT1

GND

1μF

AP3605

C1- C2-C2+

1μF

SET

ISET

PWM Dimming

1kHz to 50kHz

Li-ion

Battery

OUT2

1 2 ... 5 6 7 8 9 10 11 12 13

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Diodes AP3605 Manuel d'utilisateur Page 10

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