AAT3153 datasheet(9/14 Pages) AAT

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AAT3153

High Efficiency 1X/1.5X/2X Charge Pump

For White LED Applications

3153.2005.12.0.93

The six constant current sink inputs (D1 to D6) can

drive six individual LEDs with a maximum current

of 20mA each. The unused sink inputs must be

connected to V

OUT, otherwise the part will operate

only in 2X charge pump mode. The S

2Cwire serial

interface enables the AAT3153 and sets the current

sink magnitudes. S

2Cwire addressing allows inde-

pendent control of two groups of current sink input:

D1-D4 and D5-D6.

Constant Current Output Level Settings

The constant current sink levels for D1 to D6 are

set via the serial interface. No PWM (pulse width

modulation) or additional control circuitry are need-

ed to control LED brightness. This feature greatly

reduces the burden on a microcontroller or system

IC to manage LED or display brightness, allowing

the user to "set it and forget it." With its high-speed

serial interface (up to 1MHz data rate), the input

sink current of the AAT3153 can be changed suc-

cessively to brighten or dim LEDs, giving the users

real-time control of LED brightness. Because the

inputs D1 to D6 are true independent constant cur-

rent sinks, the voltage observed on any single

given input will be determined by the actual forward

voltage (V

F) for the LED being driven.

2Cwire Serial Interface

The current sink input magnitude on the AAT3153 is

controlled by AnalogicTech's S

2Cwire serial inter-

face.

The interface records rising edges of the

EN/SET pin and decodes them into 16 different

states, as indicated in Table 1. There are four bright-

ness levels for the main or sub-display group with

the possibility of individually turning ON or OFF

each group. To further optimize power efficiency,

the AAT3153 also offers four low-current levels for

dim LED operation (Data 13 through 16). During

this low-current mode, the internal supply current

reduces to only 50µA typical.

The S

2Cwire serial interface has flexible timing.

Data can be clocked-in at speeds greater than

1MHz, or much slower, such as 15kHz. After data

is submitted, EN/SET is held high to latch the data.

Once EN/SET has been held in the logic high state

for time T

LAT, the programmed current becomes

active and the internal data register is reset to zero.

For subsequent current level programming, the

number of rising edges corresponding to the

desired code must be entered on the EN/SET pin.

When EN/SET is held low for an amount of time

greater than T

OFF, the AAT3153 enters into shutdown

mode and draws less than 1µA from V

IN. The inter-

nal data register is reset to zero during shutdown.

Table 1: AAT3153 Current Settings.

Main Group

Sub Group

(D1-D4)

(D5-D6)

Data

OUT (mA)

120

214

310

520

614

710

0.05

0.5

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