AAT2846

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

ChargePump

TM

PRODUCT DATASHEET

2

2846.2008.03.1.1

www .analogictech.com

AAT2846

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

ChargePump

TM

PRODUCT DATASHEET

2

2846.2008.03.1.1

www .analogictech.com

Pin Descriptions

Pin # Symbol Description

1

BL3

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.

2

BL2

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.

3

BL1

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.

4

AGND

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

5CT

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

capacitor sets the timer to 1 second.

6

REF

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

7

FBB

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.

8

OUTB

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

larger ceramic capacitor as close to the AAT2846 as possible.

9, 18

IN

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

capacitor as close to the AAT2846 as possible.

10

FBA

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.

11

OUTA

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

larger ceramic capacitor as close to the AAT2846 as possible.

12

C1-

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

13

C1+

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

14

OUT

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

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

15

ENB

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.

16

C2+

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

17

C2-

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

19

PGND

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

20

ENS

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

21

FL2

Flash LED 2 current sink. FL2 controls the current through flash LED 2. Connect the cathode of flash LED 2 to

FL2. If not used, connect FL2 to OUT.

22

FL1

Flash LED 1 current sink. FL1 controls the current through flash LED 1. Connect the cathode of flash LED 1 to

FL1. If not used, connect FL1 to OUT.

23

FEN

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

current, set by RFSET, through the flash LEDs.

24

FSET

Flash current setting input. A 280kΩ resistor from FSET to AGND sets the maximum flash LED current.

25

BL6

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.

26

BL5

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.

27

ENA

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.

28

BL4

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.

EP

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