AAT4296_06 ANALOGICTECH [Advanced Analogic Technologies], AAT4296_06 Datasheet - Page 14

• Manufacturer Part Number: AAT4296_06
• Description: Five/Six Channel Push/Pull I/O Expander
• Manufacturer: ANALOGICTECH [Advanced Analogic Technologies]

Driving LED Loads
The AAT4296 and AAT4298 can be used to drive
LEDs or other applications with light load current
requirements. LED applications may include main
and sub-LCD display backlighting, camera photo-
flash applications, color (RGB) LEDs, and infrared
(IR) diodes for remotes. In series with LEDs, bal-
last resistors must be used to limit the LED current.
The LED current will vary with supply voltage and
LED forward voltage. Most types of LEDs have for-
ward voltage specifications ranging from 2.0V to
5.0V. Calculate the necessary ballast resistor value
from the following formula:
14
Figure 5: Infrared, Bluetooth, RGB, and Backlighting Control.
A series of
pulses
5V
EN/SET
Five/Six Channel Push/Pull I/O Expander
IN
AAT4296
GND
OUT1
OUT2
OUT3
OUT4
OUT5
OUT6
Where:
R
series with the LED (Ω).
V
V
R
turned on (Ω).
I
LED
IN
F
LED
DS(ON)
is the forward voltage of the LED (V).
is the input supply voltage to the device (V).
R
is the desired operating current of the LED (A).
is the resistance of resistor to be placed in
G
is the resistance of the switch when it is
B
R
LED
=
(V
EN
EN
IN
I
LED
- V
Bluetooth
Infrared
F
Device
Device
AAT4296/98
)
Backlighting
- R
DS(ON)
4296.2006.12.1.3