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PDF AAT2860 Data sheet ( Hoja de datos )
| Número de pieza | AAT2860 | |
| Descripción | Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit | |
| Fabricantes | Advanced Analogic Technologies | |
| Logotipo |  |
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ChargePumpTM
PRODUCT DATASHEET
AAT2860
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
General Description
The AAT2860-x is a highly integrated charge pump-based
lighting management unit (LMU) with three low dropout
(LDO) regulators optimized for single-cell lithium-ion/
polymer systems. The charge pump provides power for
all LED outputs; multiple backlight and flash LED configu-
rations are available. The backlight LED outputs can be
programmed up to 31mA each and the flash LED outputs
can be programmed up to 300mA each. An I2C compati-
ble serial digital interface is used to enable, disable, and
set the current to one of 32 levels for the backlight and
one of 16 levels for the flash. A programmable safety
timer and flash control input is included for easy flash
control. Backlight current matching is better than 3% for
uniform display brightness, and flash current matching is
better than 5% for uniform power dissipation.
The AAT2860-x offers three high-performance low-noise
MicroPower™ LDO linear regulators. The regulators are
enabled and their output voltages are set through the
I2C compatible serial interface. Each LDO can supply up
to 300mA load current and ground-pin current is only
80µA making the AAT2860-x ideal for battery-operated
applications.
The AAT2860-x is available in a Pb-free, space saving
TQFN34-24 package and operates over the -40°C to
+85°C ambient temperature range.
Features
• Input Voltage Range: 2.7V to 5.5V
• I2C Compatible Serial Interface
• Tri-Mode Charge Pump
▪ Drives up to Seven LEDs (Backlight/Flash)
• Programmable Backlight Current Settings
▪ 32 Levels - 0.5mA to 31mA
• Programmable Flash Current
▪ 16 Levels – OFF to 300mA
• 1MHz Switching Frequency
• Automatic Soft-Start
• Three Low Dropout Regulators
▪ 300mA Output Current
▪ 150mV Dropout
▪ Programmable Output from 1.5V to 3.0V
▪ Output Auto-Discharge for Fast Shutdown
• Built-In Thermal Protection
• -40°C to +85°C Temperature Range
• TQFN34-24 Package
Applications
• Camera Enabled Mobile Devices
• Digital Still Cameras
• Multimedia Mobile Phones
Typical Application
VBAT
3.6V
CIN
4.7µF
CIN
4.7µF
LED Select
Flash Level Select
I2C Serial SDA
Interface
SCL
LDO Select
C1 C2
1µF 1µF
C1+ C1- C2+ C2-
IN OUT
AAT2860-x
IN
LED_SEL
FL_LVL
SDA
SCL
BL1
BL2
BL3
BL4
BL5
BL6/FL1
BL7/FL2
LDOA
LDO_SEL LDOB
AGND
LDOC
PGND
WLEDs
OSRAM LW M673
or equivalent
VOUT
COUT
2.2µF
Flash LEDs
Lumiled LXCL-PWF1
or equivalent
VLDOC
at 300mA
CLDOC
2.2µF
VLDOB
at 300mA
CLDOB
2.2µF
VLDOA
at 300mA
CLDOA
2.2µF
2860.2008.05.1.0
www.analogictech.com
1
1 page  
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ChargePumpTM
PRODUCT DATASHEET
AAT2860
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Electrical Characteristics1
VIN = 3.6V; CIN = 4.7µF; COUT = CLDO(A, B, C) = 2.2μF; C1 = C2 = 1µF; TA = -40°C to +85°C, unless otherwise noted.
Typical values are TA = 25°C.
Symbol Description
LDO Regulators
ΔVLDO[A/B/C]/
VLDO[A/B/C]
LDOA, LDOB, LDOC Output
Voltage Tolerance
ILDO[A/B/C](MAX)
LDOA, LDOB, LDOC Maximum
Load Current
VLDO[A/B/C](DO)
LDOA, LDOB, LDOC Dropout
Voltage2
∆VLDO/
VLDO*∆VIN
PSRR[A/B/C]
Line Regulation
LDOA, LDOB, LDOC Power
Supply Rejection Ratio
RLDO_(DCHG)
LDOA, LDOB, LDOC Auto-
Discharge Resistance
I2C Logic and Control Interface
VIL
SDA, SCL, LED_SEL, FL_LVL,
LDO_SEL Input Low Threshold
VIH
SDA, SCL, LED_SEL, FL_LVL,
LDO_SEL Input High Threshold
IIN
SDA, SCL, LED_SEL, FL_LVL,
LDO_SEL Input Leakage Current
fSCL
tLOW
tHIGH
tHD_STA
tSU_STA
tSU_DAT
tHD_DAT
tSU_STO
tBUF
SCL Clock Frequency
SCL Clock Low Period
SCL Clock High Period
Hold Time START Condition
Setup Time for Repeat START
SDA Data Setup Time
SDA Data HOLD Time
Setup Time for STOP Condition
Bus Free Time Between STOP
and START Conditions
Conditions
ILDO = 1mA to 300mA; TA = 25°C
ILDO = 1mA to 300mA; TA = -40°C to +85°C
VLDO[A/B/C] ≥ 2.7V; ILDO = 150mA
VIN = (VLDO[A/B/C] + 1V) to 5V
ILDO[A/B/C] =10mA, 1kHz
2.7V ≤ VIN ≤ 5.5V
2.7V ≤ VIN ≤ 5.5V
SDA = SCL = LED_SEL = FL_LVL = LDO_SEL = 5V
Min
-1.5
-3
300
1.4
-1
0
1.3
0.6
0.6
0.6
500
0.5
0.6
1.3
Typ
75
0.09
40
20
0.4
Max Units
+1.5
+3
%
%
mA
150 mV
%/V
dB
Ω
V
V
1 µA
400 kHz
µs
µs
µs
µs
ns
µs
µs
µs
1. The AAT2860 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correla-
tion with statistical process controls.
2. VDO[A/B/C] is defined as VIN – LDO[A/B/C] when LDO[A/B/C] is 98% of nominal.
2860.2008.05.1.0
www.analogictech.com
5
5 Page 
www.DataSheet4U.com
ChargePumpTM
PRODUCT DATASHEET
AAT2860
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Functional Block Diagram
C1-
C1+
C2-
C2+
OUT
IN IN
1x/1.5x/2x
Tri -mode
Charge pump
LDOA
LDOB
LDOC
SDA
SCL
LED_SEL
FL_LVL
LDO_SEL
AAT2860-x
REF
7
Control
Logic
PGND
AGND
BL1
BL2
BL3
BL4
BL5
BL6/FL1
BL7/FL2
Functional Description
The AAT2860-x is a highly integrated backlight and
photo-flash driver with three LDO regulators. The charge
pump LED driver powers the backlight and flash LEDs
from the 2.7V to 5.5V input voltage. The LDO regulators
get their power from the same input and produce regu-
lated output voltage between 1.5V and 3.0V. Control of
the LEDs and the LDO output voltage is through an I2C
compatible serial interface for easy programming.
LED Drivers
The AAT2860-x drives up to seven backlight LEDs up to
31mA each and up to two flash LEDs up to 300mA each.
The LEDs are driven from a charge pump to insure that
constant current is maintained over the entire battery
voltage range. The charge pump automatically switches
from 1x, 1.5x, and 2x modes and back to maintain the
LED current while minimizing power loss for high effi-
ciency. The charge pump operates at the high 1MHz
switching frequency allowing the use of small 1μF ceram-
ic fly capacitors.
The charge pump is controlled by the voltage across the
LED current sinks. When any one of the active backlight
current sink sink/channel voltages drops below 180mV
or the flash current sink/channel drops below 450mV,
the charge pump goes to the next higher mode (from 1x
to 1.5x or from 1.5x to 2x mode) to maintain sufficient
LED voltage for constant LED current. The AAT2860-x
continuously monitors the LED forward voltages and
uses the input voltage to determine when to reduce the
charge pump mode for better efficiency. There is also a
150mV mode-transition hysteresis that prevents the
charge pump from oscillating between modes.
LED Current Control
Both the backlight and flash LED currents are controlled
through an I2C compatible serial interface. The backlight
LED current can be set between 0.5mA and 31mA in
1mA steps while the flash LED current can be set
between 0mA and 300mA in 20mA steps. The backlight
LED currents match to within 3% while the flash LED
currents match to within 5%.
To eliminate the latency of the I2C compatible serial
interface, the flash LED is enabled through a dedicated
input, FL_LVL. The AAT2860-x also include a safety
timer that prevents overstress of the flash LED(s). This
is important because many flash LEDs operate for a brief
period beyond their steady-state operating limitations. If
the flash driving hardware and/or software fails to turn
2860.2008.05.1.0
www.analogictech.com
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| Páginas | Total 23 Páginas | |
| PDF Descargar | [ Datasheet AAT2860.PDF ] | |
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