© 2003 Fairchild Semiconductor Corporation

www.fairchildsemi.com

FAN5611/FAN5612/FAN5613/FAN5614 Rev. 1.0.9

9

Example 3: Drive white, blue, red, amber LEDs string

Assuming a boost circuit or existing voltage bus, the

FAN561X series of LED drivers can be used to drive a

whole string of LEDs with flexible brightness control via

analog and/or PWM. .

Key advantage:

• No need for current matching resistors and discrete

transistor for brightness control.

LED Brightness Control

All of the FAN561X LED drivers feature analog and

PWM controls to give designers flexible brightness con-

trol. These control methods can be applied to the circuit

in two different ways to provide more flexibility than other

1. FAN5611

- Analog

- PWM

– Amplitude sets maximum LED current.

– Pulse width controls between 0 and maximum.

2. FAN5612

- Analog

- PWM - 1

– Amplitude sets maximum LED current.

– Pulse width controls between 0 and maximum.

- PWM - 2

ON/OFF = PWM

– Amplitude has no effect on current.

– Pulse width controls between 0 and maximum.

I1

I2

I3

I4

GND

FAN5613

CTRL

V

CONTROL

'N' number of

LEDs Per Branch

ON/OFF

ENABLE

I1

I2

I3

I4

GND

FAN5611

CTRL

V

I

LED

200

V

CONTROL

V

CTRL

–

()

×

R

SET

-------------------------------------------------------------------------

=

I1

I2

I3

GND

FAN5612

CTRL

V

CONTROL

ON/OFF

ENABLE

I

LED

200

V

CONTROL

V

CTRL

–

()

×

R

SET

-------------------------------------------------------------------------

=

I

LED

200

I

SET

×

∼