AAT3113,AAT3114/14A

High Efficiency 1.5X Fractional Charge Pumps For White LED Applications

PRODUCT DATASHEET

8

3113.2008.05.1.10

www .analogictech.com

AAT3113,AAT3114/14A

High Efficiency 1.5X Fractional Charge Pumps For White LED Applications

PRODUCT DATASHEET

8

3113.2008.05.1.10

www .analogictech.com

Functional Description

The AAT3113 and AAT3114/14A devices are high effi-

ciency 1.5X fractional charge pumps intended for white

LED backlight applications. The fractional charge pump

consists of a linear regulator followed by a 1.5X charge

pump. The AAT3113 and AAT3114/14A require only four

external components: two 1µF ceramic capacitors for the

charge pump flying capacitors (C1 and C2), one 1µF

verted into four or six constant current outputs (D1 to

D4 or D6) to drive four or six individual LEDs with a

maximum of 20mA each. The current source output

magnitude is controlled by the EN/SET serial data

the EN/SET pin and decodes them into 32 individual cur-

rent level settings each 1dB apart (see Table 1, Current

Level Settings). Code 32 is full scale, and Code 1 is full

scale attenuated by 31dB. The modulo 32 interface

wraps states back to state 1 after the 32nd clock. With

each EN/SET pulse, the output current increases by 1dB.

To decrease the output current by 1dB, 31 EN/SET clock

pulses are required. The counter can be clocked at

speeds up to 1MHz, so intermediate states are not visi-

ble. The first rising edge of EN/SET enables the IC and

initially sets the output LED current to -31dB, the lowest

setting equal to 525µA. Once the final clock cycle is input

for the desired brightness level, the EN/SET pin is held

high to maintain the device output current at the pro-

grammed level. The device is disabled 500µs after the

EN/SET pin transitions to a logic low state.

Functional Block Diagram

Voltage

Reference

Soft Start

600kHz

Oscillator

1.5X

Charge

Pump

Interface

32x8 bit

ROM

Current

Mode

DAC

8

5

VIN

C1+

C1-

C2+

C2-

OUT

D1

D2

D3

D4

GND

* AAT3114/14A only

EN/SET

D5*

D6*