AAT2848

High-Current Charge Pump For Backlight Display and Flash Applications

ChargePump

TM

PRODUCT DATASHEET

2

2848.2008.05.1.0

www .analogictech.com

AAT2848

High-Current Charge Pump For Backlight Display and Flash Applications

ChargePump

TM

PRODUCT DATASHEET

2

2848.2008.05.1.0

www .analogictech.com

Pin Descriptions

Pin # Symbol

Description

1

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 AAT2848 as possible.

2

C2+

Positive terminal of charge pump capacitor 2. Connect a 1μF charge pump capacitor 1 from C2+ to C2-.

3

AGND

Analog ground. Connect AGND to PGND at a single point as close to the AAT2848 as possible.

4

FADE

Fade-In/Fade-Out timing control capacitor input. Connect a capacitor from FADE to AGND to set the auto-

matic backlight current fade-in/fade-out response time. A 47nF capacitor sets the fade-in/fade-out backlight

response time to 2.7 seconds. Connect to the IN pin to disable fade functionality.

5

FLTMR

Flash timer control capacitor input. Connect a capacitor from FLTMR to AGND to set the flash timer. A 330nF

capacitor sets the flash timer to 1.3 seconds. Connect to the AGND pin to disable timer functionality.

6

BENS

serially control the backlight LED brightness relative to the maximum current set by the resistor at BSET.

7

FENS

control the flash LED brightness relative to the maximum current set by the resistor at FSET.

8

FSET

Flash current setting input. A 9.53kΩ resistor from FSET to AGND sets the maximum flash LED current to

300mA per flash output.

9

BSET

Backlight current setting input. A 10kΩ resistor from BSET to AGND sets the maximum backlight LED current

to 30mA per backlight output.

10

BL1

Backlight LED 1 current sink/channel. BL1 controls the current through backlight LED 1. Connect the cathode

of backlight LED 1 to BL1. If not used, connect BL1 to OUT.

11

BL2

Backlight LED 2 current sink/channel. BL2 controls the current through backlight LED 2. Connect the cathode

of backlight LED 2 to BL2. If not used, connect BL2 to OUT.

12

BL3

Backlight LED 3 current sink/channel. BL3 controls the current through backlight LED 3. Connect the cathode

of backlight LED 3 to BL3. If not used, connect BL3 to OUT.

13

BL4

Backlight LED 4 current sink/channel. BL4 controls the current through backlight LED 4. Connect the cathode

of backlight LED 4 to BL4. If not used, connect BL4 to OUT.

14

FL1

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

LED 1 to FL1. If not used, connect FL1 to OUT.

15

FL2

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

LED 2 to FL2. If not used, connect FL2 to OUT.

16

PGND

Power ground. Connect PGND to AGND at a single point as close to the AAT2848 as possible.

17

C2-

Negative terminal of charge pump capacitor 2.

18

C1-

Negative terminal of charge pump capacitor 1.

19

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 AAT2848 as possible.

20

C1+

Positive terminal of charge pump capacitor 1. Connect a 1μF charge pump capacitor 1 from C1+ to C1-.

EP

Exposed paddle (bottom). Connect to ground as close as possible to the device.

Pin Configuration

1

3

EP

2

5

4

15

13

14

11

12

OUT

C2+

AGND

FADE

FLTMR

BL3

BL4

BL2

FL1

FL2