AAT2846_08 Datasheet, PDF(2/22 Page) Advanced Analogic Technologies – High Current Charge Pump with Dual LDO for Backlight and Flash Applications

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AAT2846_08 Datasheet, PDF (2/22 Pages) Advanced Analogic Technologies – High Current Charge Pump with Dual LDO for Backlight and Flash Applications

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PRODUCT DATASHEET

AAT2846

ChargePumpTM High Current Charge Pump with Dual LDO for Backlight and Flash Applications

Pin Descriptions

Pin #

9, 18

Symbol

BL3

BL2

BL1

AGND

REF

FBB

OUTB

FBA

OUTA

C1-

C1+

OUT

ENB

C2+

C2-

PGND

ENS

FL2

FL1

FEN

FSET

BL6

BL5

ENA

BL4

Description

Backlight LED 3 current sink. BL3 controls the current through backlight LED 3. Connect the cathode of back-

light LED 3 to BL3. If not used, connect BL3 to OUT.

Backlight LED 2 current sink. BL2 controls the current through backlight LED 2. Connect the cathode of back-

light LED 2 to BL2. If not used, connect BL2 to OUT.

Backlight LED 1 current sink. BL1 controls the current through backlight LED 1. Connect the cathode of back-

light LED 1 to BL1. If not used, connect BL1 to OUT.

Analog ground. Connect AGND to PGND at a single point as close to the AAT2846 as possible.

Flash timer control capacitor input. Connect a capacitor from CT to AGND to set the ï¬ash timer. A 100nF

capacitor sets the timer to 1 second.

Reference output. Bypass REF to AGND with a 0.1ÂµF or larger ceramic capacitor.

Feedback input for LDO B. FBB measures the output voltage of LDO B. Connect a resistive voltage divider

from the output of LDO B to FBB. FBB feedback regulation voltage is 1.2V.

LDO B regulated voltage output. OUTB is the voltage output of LDO B. Bypass OUTB to AGND with a 2.2ÂµF or

larger ceramic capacitor as close to the AAT2846 as possible.

Power input. Connect IN to the input source voltage. Bypass IN to PGND with a 4.7ÂµF or larger ceramic

capacitor as close to the AAT2846 as possible.

Feedback input for LDO A. FBA measures the output voltage of LDO A. Connect a resistive voltage divider

from the output of LDO A to FBA. FBA feedback regulation voltage is 1.2V.

LDO A regulated voltage output. OUTA is the voltage output of LDO A. Bypass OUTA to AGND with a 2.2ÂµF or

larger ceramic capacitor as close to the AAT2846 as possible.

Negative node of charge pump capacitor 1. Connect the 1ÂµF charge pump capacitor 1 from C1+ to C1-.

Positive node of charge pump capacitor 1. Connect the 1ÂµF charge pump capacitor 1 from C1+ to C1-.

Charge pump output; supplies current to the backlight and ï¬ash LEDs. Connect the backlight and ï¬ash LED an-

odes to OUT. Bypass OUT to PGND with a 2.2ÂµF or larger ceramic capacitor as close to the AAT2846 as possible.

LDO B enable input. ENB turns on or off low dropout regulator B (LDO B). Drive ENB high to turn on LDO B;

drive it low to turn it off.

Positive node of charge pump capacitor 2. Connect the 1ÂµF charge pump capacitor 2 from C2+ to C2-.

Negative node of charge pump capacitor 2. Connect the 1ÂµF charge pump capacitor 2 from C2+ to C2-.

Power ground. Connect AGND to PGND at a single point as close to the AAT2846 as possible.

Flash and backlight enable and serial control input. ENS turns on/off both the ï¬ash and backlight and is the

AS2Cwire input to serially control the backlight and movie-mode ï¬ash LED brightness.

Flash LED 2 current sink. FL2 controls the current through ï¬ash LED 2. Connect the cathode of ï¬ash LED 2 to

FL2. If not used, connect FL2 to OUT.

Flash LED 1 current sink. FL1 controls the current through ï¬ash LED 1. Connect the cathode of ï¬ash LED 1 to

FL1. If not used, connect FL1 to OUT.

Flash enable input. FEN is the on/off control for the ï¬ash LEDs. Drive FEN high to drive the maximum ï¬ash

current, set by RFSET, through the ï¬ash LEDs.

Flash current setting input. A 280kâ¦ resistor from FSET to AGND sets the maximum ï¬ash LED current.

Backlight LED 6 current sink. BL6 controls the current through backlight LED 6. Connect the cathode of back-

light LED 6 to BL6. If not used, connect BL6 to OUT.

Backlight LED 5 current sink. BL5 controls the current through backlight LED 5. Connect the cathode of back-

light LED 5 to BL5. If not used, connect BL5 to OUT.

LDO A enable input. ENA turns on or off low dropout regulator A (LDO A). Drive ENA high to turn on LDO A;

drive low to turn it off.

Backlight LED 4 current sink. BL4 controls the current through backlight LED 4. Connect the cathode of back-

light LED 4 to BL4. If not used, connect BL4 to OUT.

Exposed paddle (bottom); connect to ground as closely as possible to the device.

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2846.2008.03.1.1

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