AAT2848 Datasheet, PDF (2/19 Pages) Advanced Analogic Technologies – High-Current Charge Pump For Backlight Display and Flash Applications

ChargePump^TM
PRODUCT DATASHEET
AAT2848
High-Current Charge Pump For Backlight Display and Flash Applications
Pin Descriptions
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
EP
Symbol
OUT
C2+
AGND
FADE
FLTMR
BENS
FENS
FSET
BSET
BL1
BL2
BL3
BL4
FL1
FL2
PGND
C2-
C1-
IN
C1+
Description
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.
Positive terminal of charge pump capacitor 2. Connect a 1μF charge pump capacitor 1 from C2+ to C2-.
Analog ground. Connect AGND to PGND at a single point as close to the AAT2848 as possible.
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.
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.
Backlight enable and serial control input. BENS is the on/off control for the backlight and the S²Cwire input to
serially control the backlight LED brightness relative to the maximum current set by the resistor at BSET.
Flash enable and serial control input. FENS is the on/off control for the flash and the S²Cwire input to serially
control the flash LED brightness relative to the maximum current set by the resistor at FSET.
Flash current setting input. A 9.53kΩ resistor from FSET to AGND sets the maximum flash LED current to
300mA per flash output.
Backlight current setting input. A 10kΩ resistor from BSET to AGND sets the maximum backlight LED current
to 30mA per backlight output.
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.
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.
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.
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.
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.
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.
Power ground. Connect PGND to AGND at a single point as close to the AAT2848 as possible.
Negative terminal of charge pump capacitor 2.
Negative terminal of charge pump capacitor 1.
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.
Positive terminal of charge pump capacitor 1. Connect a 1μF charge pump capacitor 1 from C1+ to C1-.
Exposed paddle (bottom). Connect to ground as close as possible to the device.
Pin Configuration
OUT ¹
C2+ ²
AGND ³
FADE ⁴
FLTMR ⁵
15 _FL2
14 _FL1
EP
13 _BL4
12 _BL3
11 _BL2
2
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2848.2008.05.1.0