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Function Descriptions

The A

PE1601/A is a high efficiency charge pump white LED driver. It provides 4 channels

low drop-out voltage current source to regulated 4 white LEDs current. For high efficiency,

the A

current of white LED. A

PE1601/A has an input current regulation to reduce the input ripple.

Soft Start

The A

PE1601/A includes a soft start circuit to limit the inrush current at power on and

mode switching. Soft start circuit holds the input current level long enough for output

Mode Decision

The A

PE1601/A uses a smart mode decision method to select the working mode for

maximum efficiency. Mode decision circuit senses the output and LED voltage for up/down

selection.

Dimming Control

CTRL0 and CTRL1 are used to control the on/off of White LED. When an external PWM

signal is connected to the control pin, brightness of white LED is adjusted by the duty cycle.

LED Current Setting

The current of white LED connected to A

can be estimated by following equation:

⎟

⎠

⎞

⎜

⎝

⎛

×

=

SET

ISET

LED

R

V

I

400

Thermal Shutdown

The A

PE1601/A provides a high current capability to drive 4 white LEDs. A thermal

shutdown circuit is needed to protect the chip from thermal damage. When the chip

reaches the shutdown temperature 150°C, the thermal shutdown circuit turns off the chip

to prevent the thermal accumulation in the chip.

Over Voltage Protection

The A

PE1601/A regulates the output voltage by controlling the input current. When the

output voltage reaches the designated level, the A

PE1601/A reduces the input current. And

then, the output voltage regulation also serves an over-voltage protection.

APE1601/A

Advanced Power

Electronics Corp.

White LED Driver (120mA Charge Pump with Current Source)