AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0 1
ChargePump™
General Description
The AAT2846 is a highly integrated charge pump
with dual linear regulators optimized for systems
powered from lithium-ion/polymer batteries. The
charge pump provides power for both white LED
backlight and flash. Six backlight LEDs can be driv-
en at up to 30mA each, while up to two flash LEDs
can be driven at up to 600mA total. AnalogicTech's
AS2Cwire™ (Advanced Simple Serial Control™) sin-
gle-wire 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. An external resistor sets
the maximum flash current. Backlight current match-
ing is 1% for uniform display brightness, and flash
current matching is 4% for uniform power dissipation.
The AAT2846 offers two high-performance low-
noise MicroPower™ low dropout (LDO) linear regu-
lators. Both regulators use individual enable inputs
and each will supply up to 200mA load current. LDO
ground pin current is only 80µA, making the
AAT2846 ideal for battery-operated applications.
The AAT2846 is equipped with built-in short-circuit
and over-temperature protection. The soft start cir-
cuitry prevents excessive inrush current at start-up
and mode transitions.
The AAT2846 is available in a Pb-free TQFN44-28
package and operates over the -40°C to +85°C
ambient temperature range.
Features
• Input Voltage Range: 2.7V to 5.5V
• Tri-Mode Charge Pump:
— Drives up to Six Backlight LEDs and Two
Flash LEDs
— 32 Programmable Backlight Current
Settings Ranging from 95µA to 30mA
— 16 Programmable Flash Current Settings
— Maximum Flash LED Current
Programmable using External Resistor
— 2MHz Switching Frequency
• Two Linear Regulators:
— 200mA Output Current
— 200mV Dropout Voltage
— Output Voltage Adjustable from 1.2V to
VBATTERY
— Output Auto-Discharge for Fast Shutdown
— Individual LDO Enable Inputs
• Built-In Thermal Protection
• Automatic Soft Start
• -40°C to +85°C Temperature Range
• TQFN44-28 Package
Applications
• Camera-Enabled Mobile Devices
• Digital Still Cameras
• Multimedia Mobile Phones
Typical Application
C
1
1μF
C
2
1μF
C1+ C1- C2+ C2-
IN
V
OUT
OUT
BL1
BL2
BL3
BL4
ENSENABLE/SET
ENB
EN_LDOB
V
OUT
LDOA
R
2A
R
1A
OUTA
FBA
C
OUTA
V
OUT
LDOB
R
2B
R
1B
OUTB
FBB
C
OUTB
C
BYP
0.1μF
REF
V
BAT
AAT2846
R
FSET
280k
FSET
AGND
FENEN_FLASH
IN
BL5
BL6
FL1
FL2
CT
PGND
ENA
EN_LDOA
C
IN
4.7μF
C
T
0.1μF
C
OUT
2.2μF
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
22846.2007.08.1.0
Pin Descriptions
Pin # Symbol Description
1 BL3 Backlight LED 3 current sink. BL3 controls the current through backlight LED 3. Connect the
cathode of backlight 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 backlight 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 backlight 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.
5 CT 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 larg-
er 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 anodes 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 back-
light and is the AS2Cwire input to serially control the backlight and movie-mode flash LED
brightness.
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.
Pin Configuration
TQFN44-28
(Top View)
1
2
3
4
5
6
7
89
10
28 27 26 25 24 23 22
11 12 13 14
21
20
19
18
17
16
15
BL3
BL2
BL1
A
GND
CT
REF
FBB
OUTB
IN
FBA
OUT
A
C1-
C1+
OUT
IN
PGND
C2-
C2+
ENB
ENS
FL2
FEN
FL1
FSET
BL6
BL5
ENA
BL4
Pin # Symbol Description
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 280kΩresistor 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 backlight 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 backlight 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 backlight 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.
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0 3
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
42846.2007.08.1.0
Absolute Maximum Ratings1
Thermal Information2
Symbol Description Value Units
PDMaximum Power Dissipation32W
θJA Maximum Thermal Resistance 50 °C/W
Symbol Description Value Units
IN, OUT, FL1, FL2, BL1, BL2, BL3, BL4, BL5, BL6 Voltage to PGND -0.3 to 6.0 V
FSET, CT, REF, FBB, OUTA, FBA, OUTB, ENA, ENB, FEN, ENS -0.3 to VIN + 0.3 V
C1+, C1-, C2+, C2- Voltage to PGND
PGND Voltage to AGND -0.3 to 0.3 V
TJOperating Junction Temperature Range -40 to 150 °C
TLEAD Maximum Soldering Temperature (at leads, 10 sec) 300 °C
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions
other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time.
2. Mounted on a FR4 circuit board.
3. Derate 6.25 mW/°C above 25°C ambient temperature.
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0 5
Electrical Characteristics1, 2
VIN = 3.6V; CIN = 4.7µF; COUT = 2.2µF; C1= C2= 1µF; RFSET = 280kΩ; TA= -40°C to +85°C, unless otherwise
noted. Typical values are TA= 25°C.
Symbol Description Conditions Min Typ Max Units
VIN IN Operating Voltage Range 2.7 5.5 V
1X Mode, 3.0V ≤VIN ≤5.5V, Active, 1
No Load; ENL = AGND, FEN = ENS = IN
IIN(Q) IN Operating Current 1.5X Mode, 3.0V ≤VIN ≤5.5V, Active, 4mA
No Load; ENL = AGND, FEN = ENS = IN
2X Mode, 3.0V ≤VIN ≤5.5V, Active, 5
No Load; ENL = AGND, FEN = ENS = IN
IIN(SHDN) IN Shutdown Current ENA = ENB = ENS = FEN = AGND 1.0 µA
TSD
Over-Temperature Shutdown 140 °C
Threshold
TSD(HYS)
Over-Temperature Shutdown 15 °C
Hysteresis
Charge Pump Section
IOUT OUT Maximum Output Current 600 mA
VIN(TH_H) Charge Pump Mode Hysteresis Address 0, Data 1 500 mV
fOSC
Charge Pump Oscillator TA= 25°C 2 MHz
Frequency
BL1-BL6 Backlight LED Outputs
IBL_(MAX) BL1-BL6 Maximum Current Address 0, Data 1; VIN - VF= 1.5V 18 20 22 mA
Address 12, Data 2; VIN - VF= 1.5V 30
ΔI(BL_) BL1-BL6 Current Matching2Address 0, Data 1; VIN - VF= 1.5V 1.0 %
VBL_(TH)
BL1-BL6 Charge Pump Mode 150 mV
Transition Threshold
FL1-FL2 Flash LED Outputs
IFL_(MAX) FL1-FL2 Maximum Current Address 4, Data 1; VIN - VF= 1.5V 270 300 330 mA
ΔI(FL_) FL1-FL2 Current Matching2Address 4, Data 1; VIN - VF= 1.5V 4.0 %
VFL_(TH)
FL1-FL2 Charge Pump Mode 300 mV
Transition Threshold
ENS, FEN Logic Control
VENS(L) ENS, FEN Input Low Threshold 0.4 V
VENS(H) ENS, FEN Input High Threshold 1.4 V
IENS, IFEN ENS, FEN Input Leakage Current VENS or VFEN = VIN = 5V -1.0 1.0 µA
tENS(LOW)
ENS, FEN Serial Interface VIN ≥3.3V 0.3 75 µs
Low Time
tENS(HI_MIN), ENS, FEN Serial Interface 50 ns
tENS(HI_MIN) Minimum High Time
tENS(HI_MAX), ENS, FEN Serial Interface VIN ≥3.3V 75 µs
tENS(HI_MAX) Maximum High Time
1. The AAT2846 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured
by design, characterization, and correlation with statistical process controls.
2. Current matching is defined as the deviation of any sink current from the average of all active channels.
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
62846.2007.08.1.0
Electrical Characteristics1
VIN = 3.6V; CIN = 4.7µF; COUT = 2.2µF; C1= C2= 1µF; RFSET = 280kΩ; TA= -40°C to +85°C, unless otherwise
noted. Typical values are TA= 25°C.
Symbol Description Conditions Min Typ Max Units
ENS, FEN Logic Control (continued)
tENS(OFF), ENS, FEN Off Timeout 500 µs
tFEN(OFF)
tENS(LAT), ENS, FEN Serial Interface 500 µs
tFEN(LAT) Latch Timeout
Linear Regulators
VFBA, VFBB Feedback Voltage Tolerance IOUT = 1mA to 200mA 1.17 1.2 1.23 V
ENA = ENB = IN, ENS = AGND 200
IIN Ground Pin Current ENA = IN, ENB = AGND or ENA = 150 µA
AGND, ENB = IN, ENS = AGND
IOUTA(MAX), OUTA, OUTB Maximum Load 200 mA
IOUTB(MAX) Current
VOUTA(DO), OUTA, OUTB Dropout Voltage IOUT = 150mA 150 300 mV
VOUTB(DO)
PSRRA, OUTA, OUTB Power Supply IOUT = 10mA, CREF = 10nF, 1kHz 50 dB
PSRRBRejection Ratio
VEN_(L) ENA, ENB Voltage Low Threshold 0.4 V
VEN_(H) ENA, ENB Voltage High Threshold 1.4 V
tEN_(DLY) ENA, ENB Enable Delay REF = Open 15 µs
1. The AAT2846 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured
by design, characterization, and correlation with statistical process controls.
Typical Characteristics
Turn On to 1.5X Mode Backlight
(30mA/ch; Data 1; V
IN
= 3.4V)
Time (200µs/div)
I
IN
(200mA/div)
V
SINK
(500mV/div)
V
EN
(2V/div)
V
OUT
(2V/div)
0V
0V
0V
0A
Turn On to 1X Mode Backlight
(30mA/ch; Data 1; V
IN
= 4.2V)
Time (200µs/div)
I
IN
(200mA/div)
V
SINK
(500mV/div)
V
EN
(2V/div)
V
OUT
(2V/div)
0V
0V
0V
0A
Flash Efficiency vs. Input Voltage
Input Voltage (V)
Efficiency (%)
30
40
50
60
70
80
90
100
2.73.13.53.94.34.75.15.5
72mA/ch
150mA/ch
Backlight Efficiency vs. Input Voltage
Input Voltage (V)
Efficiency (%)
30
40
50
60
70
80
90
100
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
20mA/ch
10.2mA/ch 1.6mA/ch
Flash Current Matching vs. Temperature
(150mA/Ch; Data 6)
Temperature (°C)
LED Current (mA)
130
135
140
145
150
155
160
165
170
-40 -15 10 35 60 85
Backlight Current Matching vs. Temperature
(20mA/ch; Data 1)
Temperature (°C)
LED Current (mA)
18.5
19.0
19.5
20.0
20.5
21.0
-40 -15 10 35 60 85
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0 7
Typical Characteristics
BENS, FENS Off Timeout vs. Input Voltage
Input Voltage (V)
VBENS(H), VFENS(H) (V)
100
140
180
220
260
300
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
-40°C
85°C
25°C
BENS, FENS Latch Timeout vs. Input Voltage
Input Voltage (V)
T
BENS(LAT)
, T
FENS(LAT)
(µs)
25°C
80
100
120
140
160
180
200
220
240
260
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
-40°C
25°C
BENS, FENS Low Threshold Voltage
vs. Input Voltage
Input Voltage (V)
V
BENS(L)
, V
FENS(L)
(V)
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
-40°C
25°C 85°C
BENS, FENS High Threshold Voltage
vs. Input Voltage
Input Voltage (V)
V
BENS(H)
, V
FENS(H)
(V)
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
25°C 85°C
-40°C
Turn Off from 1.5X Mode Backlight
(30mA/ch; Data 1)
Time (100µs/div)
I
IN
(200mA/div)
V
EN
(2V/div)
V
OUT
(2V/div)
0V
0V
0A
Turn On to 2X Mode Backlight
(30mA/ch; Data 1; V
IN
= 2.7V)
Time (200µs/div)
I
IN
(200mA/div)
V
SINK
(500mV/div)
V
EN
(2V/div)
V
OUT
(2V/div)
0V
0V
0V
0A
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
82846.2007.08.1.0
Typical Characteristics
LDOs A and B Line Transient Response
(10mA Load)
Time (50µs/div)
V
IN
(250mV/div)
V
OUT
(AC Coupled)
(20mV/div)
V
IN
= 3.1V
V
IN
= 3.6V
LDOs A and B Dropout Characteristics
Input Voltage (V)
Output Voltage (V)
2.0
2.2
2.4
2.6
2.8
3.0
3.2
2.7 2.8 2.9 3.0 3.1 3.2
I
OUT
= 200mA
I
OUT
= 100mA
LDOs A and B Output Voltage
vs. Temperature
Temperature (°C)
Output Voltage (%)
-1.5
-1
-0.5
0
0.5
1
1.5
-40 -15 10 35 60 85
LDOs A and B Load Regulation
Load Current (mA)
Output Voltage Error (%)
-1.0
-0.5
0.0
0.5
1.0
0.1 1 10 100 1000
OUTA
OUTB
LDOs A and B Load Regulation
Load Current (mA)
Output Voltage Error (%)
-1.0
-0.5
0.0
0.5
1.0
0.1 1 10 100 1000
OUTA
OUTB
LDOs A and B Turn On Characteristic
Time (50µs/div)
V
EN
(2V/div)
V
OUT
(500mV/div)
0V
0V
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0 9
Typical Characteristics
LDOs A and B Load Transient Response
(10mA to 200mA Load Step)
Time (50µs/div)
I
OUT
(100mA/div)
V
OUT
(AC Coupled)
(100mV/div)
I
OUT
= 200mA
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
10 2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0) 11
Functional Block Diagram
BL5
1x/1.5x/2x
Charge Pump
C1+
C1-
C2+
C2-
IN
OUT
BL1
BL2
BL3
BL4
FL1
Control
Logic
BL6
FL2
AGND
ENB
ENS
To LDO B
CT
FEN
FSET
PGND
ENA To LDO A
FBA
OUT
1.2V
V
REF
FBB
OUTB
LDO A
LDO B
IN
REF
Functional Description
The AAT2846 is a highly integrated backlight and
flash LED driver with two LDO linear regulators.
The charge pump LED driver drives backlight and
flash LEDs from a 2.7V to 5.5V input voltage. The
LDO regulators are operated from the same input
voltage range and produce regulated output volt-
ages as low as 1.2V.
LED Drivers
The LEDs are driven from an internal charge pump
that, depending on the battery voltage and LED for-
ward voltage, drives LEDs directly from the supply
voltage (1X or bypass mode) or steps up the sup-
ply voltage by a factor of 1.5 (1.5X mode) or 2 (2X
mode). The charge pump requires only two tiny
1µF ceramic capacitors, providing a more compact
solution than typical inductor-based step-up con-
verter solutions. Each individual LED is driven by a
current sink to AGND, allowing individual current
control with high accuracy over a wide range of
input voltages and LED forward voltages while
maintaining high efficiency.
The charge pump is controlled by the voltage across
the LED current sinks. When any one of the active
current sinks begins to dropout, 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 AAT2846 con-
tinuously 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 500mV mode-transition hysteresis that pre-
vents the charge pump from oscillating between
charge pump modes.
The backlight and flash LED current levels are
dynamically controllable by the AS2Cwire single-wire
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
12 2846.2007.08.1.0
interface. The backlight section has multiple current
level scales and the maximum current level is fixed at
20mA or 30mA, depending on the scale chosen
through programming. The flash section maximum
current level is user programmable by an external set
resistor. The maximum flash current that can be sup-
ported by the device is 300mA/channel, or 600mA
total. This corresponds to a 280K set resistor value.
For maximum LED current lower than 300mA, use
a programming resistor greater than 280kΩup to
1MΩ. Calculate the flash programming resistor
value using the equation:
where IFMAX is the maximum flash LED current in mA.
If any one of the backlight or flash current sinks is
not used, connect that current sink to OUT. The
current controller monitors the sink voltage and, if it
is connected to OUT, then the controller deter-
mines that the current sink is not used or that the
LED is shorted. In either case, the controller turns
off the affected current sink.
AS2Cwire Serial Interface
The AAT2846 is dynamically programmable by the
AS2Cwire single-wire interface. AS2Cwire records
rising edges detected at the ENS pin to address
and load the data registers. AS2Cwire latches data
or address after the ENS input has been held high
for time TLAT (500µs). Address or data is differenti-
ated by the number of ENS rising edges. Since the
data registers are 4 bits each, the differentiating
number of pulses is 24or 16, so that Address 0 is
identified by 17 rising edges, Address 1 by 18 ris-
ing edges, Address 2 by 19 rising edges, etc. Data
is set to any number of rising edges between 1 and
16. A typical write protocol is a burst of ENS rising
edges identifying a particular address, followed by
a pause with ENS held high for the TLAT timeout
period, then a burst of rising edges signifying data,
and another TLAT timeout after the data has been
sent. Once an address is set, multiple writes to that
address are allowed since the address is not reset
after each write. Address edges are needed when
changing the address, or writing to an address
other than the default after shutdown. Address 0 is
the default address after shutdown. If the part is
enabled with only data edges and no address, then
Address 0 will be programmed and backlight chan-
nels BL1-BL6 will turn-on according to the number
of data edges applied.
When ENS is held low for a time greater than TOFF
(500µs), the AAT2846 enters shutdown mode and
draws less than 1µA of current from IN. At shut-
down, the data and address registers are reset to 0.
AS2Cwire Serial Interface Addressing
Table 1: AS2Cwire Serial Interface Addressing.
Backlight Current Control (Address 0-3)
Use Addresses 0-3 to program all six backlight LED
channels. All six backlight channels are pro-
grammed to the same current level by writing
Address 0 followed by any Data between 1 and 16.
To program only the main channels BL1 through
BL5, use Address 1. Similarly, use Address 2 to
independently program subchannel BL6 only.
ENS
Rising
Address Edges Function
0 17 Backlight Current BL1-BL6
1 18 Main Backlight Current
BL1-BL5
2 19 Sub Backlight Current BL6
3 20 Low Current Backlight
4 21 Flash Current FL1, FL2
5 22 Independent Flash On/Off
Control
12 29 Maximum Backlight Current
(Main and Sub)
15 32 Backlight Independent
Control
Sub-2 19 BL3-BL6 On/Off Control
Sub-3 20 BL1/BL2 On/Off Control
R
FSET
= Ω
280k · 300mA
I
FMAX
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0 13
Table 2:
Data Code for Backlight Current Level
,
Address 0-2.
Figure 2:
Data Code for
Address 0-2 vs.
Backlight Current Level
.
The AAT2846 incorporates additional circuitry that
optimizes performance for exceptionally low back-
light current settings. A separate address is used to
activate this circuitry. To program the low current
settings with improved performance and efficiency,
write to Address 3. Unlike Addresses 0-3, which
have current level settings according to Table 2 and
Figure 2, Address 3 possesses a separate set of
current levels described by the Low Current
Backlight settings found in Table 3.
Table 3: Data Code for Low-Level Backlight
Current, Address 3, FS = 20mA range.
Main Sub Current
Data Current On Current On (µA)
1No No 0
2No No 0
3No No 0
4No No 0
5 No Yes 95
6 No Yes 500
7 No Yes 950
8 No Yes 1900
9 Yes No 95
10 Yes No 500
11 Yes No 950
12 Yes No 1900
13 Yes Yes 95
14 Yes Yes 500
15 Yes Yes 950
16 Yes Yes 1900
Data Code
I
BLED
(mA)
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
30mA (Full Scale)
20mA (Full Scale)
Data 30mA Max (mA) 20mA Max (mA)
1 30.0 20.0
2 27.9 19.0
3 26.1 17.8
4 24.2 16.5
5 21.0 14.3
6 19.2 13.0
7 17.3 11.8
8 15.0 10.2
9 12.7 8.5
10 10.9 7.3
11 8.1 5.4
12 6.2 4.1
13 4.4 2.9
14 3.5 2.2
15 2.6 1.6
16 0 0
Figure 1: AS2Cwire Serial Interface Timing.
Address Data
1
EN/SET
217 18
Address
Data Reg 1
Data Reg 2
12 . . . n ≤ 16
01
0
0
n
T
HI
T
LO
T
LAT
T
LAT
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
14 2846.2007.08.1.0
Flash Current FL1, FL2 (Address 4)
The current level for the flash channels FL1 and
FL2 is programmed by Address 4. Data 1 enables
the maximum current level. The maximum current
level is determined by the value of RFSET. Table 4
and Figure 3 illustrate the additional flash current
levels that are available.
Table 4: Data Code for the Flash Current
Control, Address 4.
Figure 3: Data Code for Address 4 vs.
percentage of Flash Current Level.
Independent Flash ON/OFF Control
(Address 5)
Use Address 5 to program which flash channels
are active. By default, both flash channels are OFF
at startup. After writing to Address 4 to program the
desired flash channel current level, write to
Address 5 to enable a single channel or both chan-
nels according to Table 5.
Table 5: Output Enable Control, Address 5.
Writing to Address 5 enables the flash channels
indefinitely. FL1 and FL2 will remain ON until
Address 5 is re-programmed to OFF, ENS is
strobed low to shutdown the device, or the flash
safety timer times out after FEN has been strobed
high. The flash safety timer is always activated
when FEN is taken high. The Address 5 data set-
ting is always reset to Data 1 when the flash timer
expires or when FEN is strobed low.
Maximum Backlight Current (Address 12)
There are two separate current level scales that apply
to Addresses 0-2: 20mA and 30mA. According to the
Maximum Backlight Current setting at Address 12,
only one of the two scales can be active at any given
time and never both. By default, the 20mA scale is
active on startup. To change to the 30mA scale, or go
back to the 20mA scale, write to Address 12.
Since only one of the scales can be active at any
given time, the 20mA and 30mA scales cannot be
mixed between main and sub. When setting Address
12 to the 30mA scale, only current levels from that
scale can be mixed between main and sub.
Table 6: Data Code for the Maximum Current
Settings, Address 12.
Data Maximum Current
1 20mA
2 30mA
Data FL1 FL2
1 Off Off
2Off On
3 On Off
4 On On
Data Code
IFLED (% of FL Maximum)
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
IFLED = 100%
at Data 1
IFLED = 14%
at Data 16
Flash LED Current
Data (% of Maximum)
1 100
287
377
466
558
650
744
839
935
10 30
11 27
12 24
13 20
14 17
15 16
16 14
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0 15
Backlight Independent Channel Control
(Address 15)
The AAT2846 has a unique independent channel
control mode whereby individual backlight LED
channels can be enabled and disabled to form a
custom arrangement of active channels.
To enable independent channel control mode, write
Data 8 to Address 15. To exit individual mode con-
trol, the AAT2846 state machine can be reset by
strobing ENS low and holding ENS low longer than
the A2SCwire's tOFF latch time.
Table 7: Data Code for Independent
Backlight Control, Address 15.
With independent channel control mode enabled,
Addresses 2 and 3 are re-mapped according to
Tables 8 and 9. As indicated by the possible set-
tings listed in the tables, any combination of back-
lighting channels can be enabled and disabled.
Because Addresses 2 and 3 are re-mapped when
independent channel control mode is enabled, the
functions originally assigned to Addresses 2 and 3
are no longer available.
It is also important to note that Address 0 is dis-
abled when independent channel control mode is
enabled. Additionally, Address 3 is disabled and the
very low current settings cannot be used in this
mode. Other addresses are unmodified by this
mode so that the flash features can still be operat-
ed and the 30mA backlight scale can still be used.
The LDO enables are always independent of
AS2Cwire programming.
Flash LED Current Control
The flash LEDs are driven through current sinks
FL1 and FL2. There are two ways to drive the flash
LEDs: either through the AS2Cwire serial interface
or through the flash enable input, FEN. The
AAT2846 also includes an adjustable safety timer
to turn off the flash in the event of a controller fault
to prevent overstressing the flash LEDs.
Table 8: Data Code for BL3-BL6
On/Off Control, Sub-Address 2.
Table 9: : Data Code for BL1 and BL2
On/Off Control, Sub-Address 3.
Flash/Movie Mode Operation
The flash LED current level is set via the serial inter-
face according to a logarithmic scale where each
code is 1.2dB lower than the previous code as a per-
Data BL2 BL1
1 Off Off
2 Off Off
3 Off Off
4 Off Off
5OffOn
6OffOn
7OffOn
8OffOn
9OnOff
10 On Off
11 On Off
12 On Off
13 On On
14 On On
15 On On
16 On On
Data BL6 BL5 BL4 BL3
1 Off Off Off Off
2 Off Off Off On
3 Off Off On Off
4 Off Off On On
5 Off On Off Off
6 Off On Off On
7 Off On On Off
8 Off On On On
9 On Off Off Off
10 On Off Off On
11 On Off On Off
12 On Off On On
13 On On Off Off
14 On On Off On
15 On On On Off
16 On On On On
Data Individual Backlight Control
8On
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
16 2846.2007.08.1.0
centage of the maximum current set by an external
resistor, RFSET from FSET to AGND. Flash LED cur-
rent is set between 14% and 100% of the maximum
current for both channels through Address 4. For
lower current applications such as torch, flashlight,
or movie light, write to Address 5 to enable only FL1
or only FL2. For higher LED current, the flash chan-
nels can be connected in parallel to drive the sum of
the two channel currents into a single LED.
Flash Strobe Input
The AAT2846 features an active high flash enable
input, FEN, that overrides the AS2Cwire program-
ming and drives both flash outputs, FL1 and FL2, at
the maximum current set by the flash current set-
ting resistor RFSET. This signal also triggers an
internal protection timer. When the FEN input is
strobed low, the flash current is turned off inde-
pendent of the internal timer. If FEN remains high
at the end of the protection timer period, the flash
LEDs are turned off. Make sure that the maximum
time set by the external CTcapacitor is such that
the flash LEDs remain within their power dissipa-
tion limit at the maximum current set by RFSET.
Contact the LED manufacturer for details on the
thermal limitations of the LEDs used. When FEN is
used to control the flash LEDs, flash on/off control
set by Address 6 is automatically reset.
Flash Protection Timer
The AAT2846 includes a protection timer set by the
capacitor CTconnected from CTto AGND. The
timer is used to avoid thermal issues with flash
LEDs operating above their continuous power rat-
ing should a data error occur in the controller. The
flash protection time, TF, is calculated by the fol-
lowing equation:
where TFis in seconds and CTis in µF.
For example: if CT= 0.1µF:
Low Dropout Regulators
The AAT2846 includes two independent LDO linear
regulators. The regulators operate from a 2.7V to
5.5V input voltage at IN. The AAT2846 supplies
separate LDO enable inputs (ENA and ENB) to
control individually the operation of the LDOs. The
LDO output voltages are set through resistive volt-
age dividers from the output (OUTA or OUTB) to
the feedback input (FBA or FBB). The regulator
controls the output voltage such that the voltage
divider output is at the 1.2V feedback threshold.
The low 200mV dropout voltage at 200mA load cur-
rent allows the regulator to maintain output voltage
regulation.
Each LDO regulator can supply up to 200mA con-
tinuous current to the load. They include current
limiting and thermal overload protection to prevent
damage to the load or to the LDOs.
T
F
= 10 · 0.1μF
= 1s
T
F
= 10 · C
T
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0 17
Applications Information
LDO Output Voltage Programming
The output voltages for LDOA and LDOB are pro-
grammed by an external resistor divider network.
As shown below, the selection of R1 and R2 is a
straight forward matter.
R1 is chosen by considering the tradeoff between
the feedback network bias current and resistor
value. Higher resistor values allow stray capaci-
tance to become a larger factor in circuit perform-
ance whereas lower resistor values increase bias
current and decrease efficiency.
To select appropriate resistor values, first choose R1
such that the feedback network bias current is less
than 10µA. Then, according to the desired VOUT, cal-
culate R2 according to the equation below. An exam-
ple calculation follows.
An R1 value of 120K is chosen, resulting in a small
feedback network bias current of 1.2V/120K = 10µA.
The desired output voltage is 1.8V. From this infor-
mation, R2 is calculated from the equation below.
The result is R2 = 60K. Since 60K is not a standard
1%-value, 60.4K is selected. From this example
calculation, for VOUT = 1.8V, use R1 = 120K and R2
= 60.4K. Example output voltages and correspon-
ding resistor values are provided in Table 11.
Table 10: Example Output Voltages and
Corresponding Resistor Values
Altering the Maximum Flash LED
Current Level
RFSET determines the maximum LED current level at
each of the F1 and F2 flash LED outputs. In the typ-
ical application, selecting RFSET = 280K results in
300mA/ch LED current. From this reference point,
the maximum current level can be modified by cal-
culating an alternative RFSET value:
This is illustrated in Figure 4.
Figure 4: Maximum Flash LED Current
vs. RFSET.
R
FSET
(kΩ
Ω
)
I
FLED
(mA)
0
50
100
150
200
250
300
350
400
450
100 200 300 400 500 600 700 800 900 1000 1100
R
FSET
= 300mA · 280kΩ
I
LED(MAX)
R2 Standard 1% Values (R1 = 120K)
VOUT (V) R2 (Ω)
2.8 160K
2.5 130K
2.0 79.6K
1.8 60.4K
1.5 30.1K
R
2
= R
1
(V
OUT
- 1.2V)
1.2V
R2(A/B)
R1(A/B)
V
OUT(A/B)
OUT(A/B)
FB(A/B)
V
REF(A/B)
= 1.2V
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
18 2846.2007.08.1.0
Selection of set resistor values outside of the typical
application must be carefully evaluated to ensure
that the application's performance requirements
can still be met.
Device Power Efficiency
The AAT2846 power conversion efficiency depends
on the charge pump mode. By definition, device effi-
ciency is expressed as the output power delivered to
the LEDs divided by the total input power consumed.
When the input voltage is sufficiently greater than
the LED forward voltages, the device optimizes
efficiency by operating in 1X mode. In 1X mode,
the device is working as a bypass switch and pass-
ing the input supply directly to the output. By sim-
plifying the conditions such that the LEDs have uni-
form VF, the power conversion efficiency can be
approximated by:
Due to the very low 1X mode quiescent current, the
input current nearly equals the total output current
delivered to the LEDs. Further, the low-resistance
bypass switch introduces negligible voltage drop
from input to output.
The AAT2846 further maintains optimized perform-
ance and efficiency by detecting when the input
voltage is not sufficient to sustain LED drive cur-
rent. The device automatically switches to 1.5X
mode when the input voltage drops too low in rela-
tion to the LED forward voltages.
In 1.5X mode, the output voltage can be boosted to
3/2 the input voltage. The 3/2 conversion ratio
introduces a corresponding 1/2 increase in input
current. For ideal conversion, the 1.5X mode effi-
ciency is given by:
Similarly, when the input falls further, such that
1.5X mode can no longer sustain LED drive cur-
rent, the device will automatically switch to 2X
mode. In 2X mode, the output voltage can be
boosted to twice the input voltage. The doubling
conversion ratio introduces a corresponding dou-
bling of the input current. For ideal conversion, the
2X mode efficiency is given by:
LED Selection
The AAT2846 is designed to drive high-intensity
white LEDs. It is particularly suitable for LEDs with
an operating forward voltage in the range of 1.5V to
4.2V.
The charge pump can also drive other loads that
have similar characteristics to white LEDs. For var-
ious load types, the AAT2846 provides a high-cur-
rent, programmable ideal constant current source.
Capacitor Selection
Careful selection of the four external capacitors
CIN, C1, C2, and COUT is important because they will
affect turn-on time, output ripple, and transient per-
formance. Optimum performance will be obtained
when low equivalent series resistance (ESR)
ceramic capacitors are used. In general, low ESR
may be defined as less than 100mΩ.
Ceramic composition capacitors are highly recom-
mended over all other types of capacitors for use
with the AAT2846. Ceramic capacitors offer many
advantages over their tantalum and aluminum elec-
trolytic counterparts. A ceramic capacitor typically
has very low ESR, is lowest cost, has a smaller
PCB footprint, and is non-polarized. Low ESR
ceramic capacitors help maximize charge pump
transient response. Since ceramic capacitors are
non-polarized, they are not prone to incorrect con-
nection damage.
η ==
V
F
· I
LED
V
IN
· 2I
IN
V
F
2 · V
IN
η ==
V
F
· I
LED
V
IN
· 1.5I
IN
V
F
1.5 · V
IN
η = ≈
V
F
· I
LED
V
IN
· I
IN
V
F
V
IN
η = P
OU
T
P
IN
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0 19
Equivalent Series Resistance
ESR is an important characteristic to consider
when selecting a capacitor. ESR is a resistance
internal to a capacitor that is caused by the leads,
internal connections, size or area, material compo-
sition, and ambient temperature. Capacitor ESR is
typically measured in milliohms for ceramic capac-
itors and can range to more than several ohms for
tantalum or aluminum electrolytic capacitors.
Ceramic Capacitor Materials
Ceramic capacitors less than 0.1µF are typically
made from NPO or C0G materials. NPO and C0G
materials generally have tight tolerance and are
very stable over temperature. Larger capacitor val-
ues are usually composed of X7R, X5R, Z5U, or
Y5V dielectric materials. Large ceramic capacitors
are often available in lower-cost dielectrics, but
capacitors greater than 10µF are not typically
required for AAT2846 applications.
Capacitor area is another contributor to ESR.
Capacitors that are physically larger will have a
lower ESR when compared to an equivalent mate-
rial smaller capacitor. These larger devices can
improve circuit performance when compared to an
equal value capacitor in a smaller package size.
PCB Layout
To achieve adequate electrical and thermal per-
formance, careful attention must be given to the
PCB layout. In the worst-case operating condition,
the chip must dissipate considerable power at full
load. Adequate heat-sinking must be achieved to
ensure intended operation.
Figure 5 illustrates an example PCB layout. The
bottom of the package features an exposed metal
paddle. The exposed paddle acts, thermally, to
transfer heat from the chip and, electrically, as a
ground connection.
The junction-to-ambient thermal resistance (θJA) for
the connection can be significantly reduced by fol-
lowing a couple of important PCB design guidelines.
The PCB area directly underneath the package
should be plated so that the exposed paddle can be
mated to the top layer PCB copper during the re-
flow process. Multiple copper plated thru-holes
should be used to electrically and thermally connect
the top surface paddle area to additional ground
plane(s) and/or the bottom layer ground pour.
The chip ground is internally connected to both the
paddle and to the AGND and PGND pins. It is good
practice to connect the GND pins to the exposed
paddle area with traces as shown in the example.
The flying capacitors C1 and C2 should be con-
nected close to the IC. Trace length should be kept
short to minimize path resistance and potential
coupling. The input and output capacitors should
also be placed as close to the chip as possible.
Figure 5: Example PCB Layout.
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
20 2846.2007.08.1.0
Evaluation Board User Interface
The user interface for the AAT2846 evaluation
board is provided through 4 buttons and a number
of connection terminals. The board is operated by
supplying external power and pressing individual
buttons or button combinations. The table below
indicates the function of each button or button
combination.
To power-on the board, connect a power supply or
battery to the DC- and DC+ terminals. Make the
board's supply connection by positioning the J1
jumper to the ON position. A red LED indicates that
power is applied.
The evaluation board is made flexible so that the
user can disconnect the enable lines from the
microcontroller and apply external enable signals.
By removing the jumpers from J2, J3, J4 and/or J5,
external enable signals can be applied to the
board. External enable signals must be applied to
pin 1 of each J2, J3, J4 or J5 terminal.
When applying external enable signals, considera-
tion must be given to the voltage levels. The exter-
nally applied voltages cannot exceed the supply volt-
age that is applied to the IN pins of the device (DC+).
The LDO loads can be connected directly to the
evaluation board. For adequate performance, be
sure to connect the load between OUTA/OUTB and
DC- as opposed to some other GND in the system.
Evaluation Board Layout
Figure 6: AAT2846 Evaluation Board Figure 7: AAT2846 Evaluation Board
Layout Top Side. Layout Bottom Side.
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0 21
Table 11: AAT2846 Evaluation Board User Interface.
Evaluation Board Schematics
Figure 8: AAT2846 Section Schematic
C1
1.0μF
C2
1.0μF
C3
2.2μF
C4
4.7μF
D1 D2 D3 D4 D6
VOUT
R10
280K
C6
2.2μF
R11
160K
R12
120K
C7
2.2μF
60.4K
R13
120K
R14
C8
0.1μF
C9
0.1μF
D5
VOUT
OUTB
OUTA
DC+
123
J1
ENLA
C5
2.2μF
ENLB
Programmed for 2.8V
output by default
Programmed for 1.8V
output by default
optional 100μF
lab supply bypass
100μF
C12 280K yields
300mA/chnl
max flash
ENFL
CTRL_CT
D3
1
D4
28
D2
2
D1
3
AGND
4
CT
5
CREF
6
OUTB
8
IN
9
FBA
10
OUTA
11
C1-
12
C1+
13
C2+
16
C2-
17
IN
18
PGND
19
ENS
20
F2
21
FEN
23
FSET
24
D6
25
D5
26
ENA
27
FBB
7
OUT
14
ENB
15
F1
22
U1
D7 D8
ENBL
VIN
Button(s) Pushed Description
DATA Increment the data setting for the most recently activated mode. With backlight or
movie mode activated, hold down the button to auto-cycle through the brightness levels.
LIGHT Toggle ON/OFF the backlighting section. Set the brightness level using the DATA button
(defaults to Data 1).
LIGHT+DATA Decrement the brightness setting for backlight mode. Hold down to auto-cycle.
MOVIE Toggle ON/OFF movie mode illumination. Set the brightness level using the DATA but-
ton (defaults to Data 10).
MOVIE+DATA Decrement the brightness setting for movie mode. Hold down to auto-cycle.
FLASH Generate a flash pulse. Pulse duration is the lesser of 2 seconds or the CT value result.
Set the brightness level using the DATA button (defaults to Data 1).
FLASH+DATA Toggle ON/OFF the LDOs.
LIGHT+MOVIE+FLASH Reset. Clear all data and bring all enable lines low.
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
22 2846.2007.08.1.0
Figure 9: MCU and I/O Expander Section Schematic
VDD
1
GP5
2
GP4
3
GP3
4
GP2
5
GP1
6
GP0
7
VSS
8
PIC12F675
U2
330
R5
RED
LED7
ENBL
J2
100K
R7
100K
R6
DATA SW1
LIGHT SW2
MOVIE SW3
FLASH SW4
1K
R1
VIN
ENBL
VIN
1K
R2
1K
R3
1K
R4
DC-
ENFLJ3
CTRL_CT
ENLAJ4
100K
R8
VIN
ENFL
ENLA
IN
1
OUT2
2
OUT1
3
EN/SET
4
GND
5
OUT5
6
OUT4
7
OUT3
8
AAT4290
U3
ENLBJ5
100K
R9
ENLB
C11
0.1μF
C10
0.1μF
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0 23
Evaluation Board Component Listing
Component Part# Description Manufacturer
U1 AAT2846INJ-EE-T1 High Eff. 1X/1.5X/2X CP for White LED, AnalogicTech
Dual LDO
U2 PIC12F675 8-bit CMOS, FLASH MCU; 8-pin PDIP Microchip
U3 AAT4290IJS-1-T1 I/O Expander AnalogicTech
D1-D6 LW M673 Mini TOPLED White LED; SMT OSRAM
D7, D8 LXCL-PWF1 Luxeon Flash LED Lumileds
C1, C2 GRM18x 1.0µF, 10V, X5R, 0603, Ceramic Murata
C3-C7 GRM18x 2.2µF, 10V, X5R, 0603, Ceramic Murata
C4 GRM18x 4.7µF, 10V, X5R, 0603, Ceramic Murata
C8-C11 GRM18x 0.1µF, 16V, X7R, 0603, Ceramic Murata
C12 TAJBx 100µF, 10V, 10µA, Tantalum AVX
R1-R4 Chip Resistor 1K, 5%, 1/4W; 1206 Vishay
R5 Chip Resistor 330, 5%, 1/4W; 1206 Vishay
R6-R9 Chip Resistor 100K, 5%, 1/10W; 0603 Vishay
R10 Chip Resistor 280K, 1%, 1/10W; 0603 Vishay
R11 Chip Resistor 160K, 1%, 1/10W; 0603 Vishay
R12, R14 Chip Resistor 120K, 1%, 1/10W; 0603 Vishay
R13 Chip Resistor 60.4K, 1%, 1/10W; 0603 Vishay
J1-J5 PRPN401PAEN Conn. Header, 2mm Zip Sullins Electronics
LED7 CMD15-21SRC/TR8 Red LED; 1206 Chicago Miniature Lamp
SW1-SW4 PTS645TL50 Switch Tact, SPST, 5mm ITT Industries
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
24 2846.2007.08.1.0
Ordering Information
Package Information3
TQFN44-28-0.4
All dimensions in millimeters.
4.000
±
0.050
4.000
±
0.050
Pin 1 Dot
by Marking
Top View
2.600 ± 0.050
2.600 ± 0.050
Bottom View
Detail "A"
0.750 ± 0.050
0.050 ± 0.050
0.203 REF
Side View
0.400 ± 0.050
0.230
±
0.050
0.430
±
0.050
Pin 1 Indicator
Detail "A"
C0.3
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means
semiconductor products that are in compliance with current RoHS standards, including
the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more
information, please visit our website at http://www.analogictech.com/pbfree.
Package Marking1Part Number (Tape and Reel)2
TQFN44-28-0.4 UPXYY AAT2846INJ-EE-T1
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the
lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required
to ensure a proper bottom solder connection.
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
2846.2007.08.1.0 25
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
© Advanced Analogic Technologies, Inc.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work
rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service with-
out notice. Except as provided in AnalogicTech’s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied war-
ranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent,
copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the
customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty.
Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated.
All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.