Driving white LED display module backlights

and individual white LEDs connected in parallel:

The AAT3114/14A D1 to D6 outputs are true con-

stant current sources capable of driving up to 20mA

each over the operation input voltage range. Since

these outputs are true constant current sources,

they may be connected in parallel to drive a single

power output. Any combination of outputs (D1 to

D6) may be connected in parallel. The maximum

total output current is a sum of parallel-connected

current sources. This feature is particularly useful

to power pre-manufactured display modules that are

pre-wired with white LED backlights connected in a

parallel circuit configuration. All outputs can be con-

nected in parallel to drive groups of LEDs as well.

The internal current source reference circuit bases

feedback from current sensed on the D1 output. For

best operation, the only requirement for this applica-

tion is that the output D1 should always be connect-

ed to the load circuit.

AAT3113, AAT3114/14A

High Efficiency 1.5X Fractional Charge

Pumps For White LED Applications

3113.2006.07.1.9

13

AAT3114/14A Application Driving a Display Module With Six Parallel-Connected White LEDs:

AAT3114/14A Dual Backlight Control Circuit:

1

μF

1

μF

EN/SET

C1

1

μF

C2

1

μF

D2

D3

D4

VIN

OUT

C1+

C1-

C2+

C2-

D1

D2

D3

D4

EN/SET

GND

AAT3114/14A

D5

D6

D1

D5

D6

Enable Display Backlight

Enable Keyboard Backlight

Display Backlight

Keyboard Backlight

1

μF

1

μF

EN/SET

C1

1

μF

C2

1

μF

D2

D3

D4

D5

VIN

OUT

C1+

C1-

C2+

C2-

D1

D2

D3

D4

EN/SET

GND

AAT3114/14A

D5

D6

D1

D6

Display Module

R1

R2

R3

R4

R5

R6

Resistor R is optional