AAT2846INJ-EE-T1 [ANALOGICTECH]
High Current Charge Pump with Dual LDO for Backlight and Flash Applications; 高电流电荷泵，带有双LDO用于背光和闪光应用
| 型号： | AAT2846INJ-EE-T1 |
| 厂家： | 
ADVANCED ANALOGIC TECHNOLOGIES |
| 描述： | High Current Charge Pump with Dual LDO for Backlight and Flash Applications |
| 文件： | 总25页 (文件大小：646K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
™
ChargePump
General Description
Features
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
•
•
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
2
AS Cwire™ (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.
Applications
The AAT2846 is available in a Pb-free TQFN44-28
package and operates over the -40°C to +85°C
ambient temperature range.
•
•
•
Camera-Enabled Mobile Devices
Digital Still Cameras
Multimedia Mobile Phones
Typical Application
C1
1μF
C2
1μF
C1+
C1- C2+
C2-
VOUT
IN
OUT
COUT
2.2μF
CIN
4.7μF
VBAT
IN
AAT2846
BL1
BL2
BL3
BL4
BL5
BL6
FL1
FL2
ENABLE/SET
ENS
FEN
EN_FLASH
CT
CT
0.1μF
FSET
RFSET
280k
OUTA
VOUT LDOA
REF
R2A
R1A
COUTA
CBYP
0.1μF
FBA
VOUT LDOB
COUTB
OUTB
FBB
ENA
ENB
EN_LDOA
EN_LDOB
R2B
R1B
AGND PGND
2846.2007.08.1.0
1
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Pin Descriptions
Pin # Symbol Description
1
2
3
BL3
BL2
BL1
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.
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.
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.
Analog ground. Connect AGND to PGND at a single point as close to the AAT2846 as possible.
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.
4
5
AGND
CT
6
7
REF
FBB
Reference output. Bypass REF to AGND with a 0.1µF or larger ceramic capacitor.
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.
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.
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.
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.
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.
Negative node of charge pump capacitor 1. Connect the 1µF charge pump capacitor 1 from
C1+ to C1-.
8
9, 18
10
OUTB
IN
FBA
OUTA
C1-
11
12
13
C1+
OUT
Positive node of charge pump capacitor 1. Connect the 1µF charge pump capacitor 1 from
C1+ to C1-.
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.
14
15
16
17
ENB
C2+
C2-
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.
Positive node of charge pump capacitor 2. Connect the 1µF charge pump capacitor 2 from
C2+ to C2-.
Negative node of charge pump capacitor 2. Connect the 1µF charge pump capacitor 2 from
C2+ to C2-.
19
20
PGND
ENS
Power ground. Connect AGND to PGND at a single point as close to the AAT2846 as possible.
Flash and backlight enable and serial control input. ENS turns on/off both the flash and back-
light and is the AS Cwire input to serially control the backlight and movie-mode flash LED
2
brightness.
21
22
FL2
FL1
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.
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.
2
2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Pin # Symbol Description
23
24
25
26
27
28
EP
FEN
FSET
BL6
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.
Flash current setting input. A 280kΩ resistor from FSET to AGND sets the maximum flash LED
current.
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.
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.
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.
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.
Exposed paddle (bottom); connect to ground as closely as possible to the device.
BL5
ENA
BL4
Pin Configuration
TQFN44-28
(Top View)
28
27
26
25
24
23
22
1
2
3
4
5
6
7
21
20
19
18
17
16
15
BL3
BL2
BL1
FL2
ENS
PGND
IN
C2-
C2+
ENB
AGND
CT
REF
FBB
8
9
10
11
12
13
14
2846.2007.08.1.0
3
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
1
Absolute Maximum Ratings
Symbol
Description
Value
Units
IN, OUT, FL1, FL2, BL1, BL2, BL3, BL4, BL5, BL6 Voltage to PGND
FSET, CT, REF, FBB, OUTA, FBA, OUTB, ENA, ENB, FEN, ENS
C1+, C1-, C2+, C2- Voltage to PGND
-0.3 to 6.0
-0.3 to VIN + 0.3
V
V
PGND Voltage to AGND
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
-0.3 to 0.3
-40 to 150
300
V
°C
°C
TJ
TLEAD
2
Thermal Information
Symbol
Description
Maximum Power Dissipation
Value
Units
W
3
PD
2
θJA
Maximum Thermal Resistance
50
°C/W
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.
4
2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
1, 2
Electrical Characteristics
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,
No Load; ENL = AGND, FEN = ENS = IN
1.5X Mode, 3.0V ≤ VIN ≤ 5.5V, Active,
No Load; ENL = AGND, FEN = ENS = IN
2X Mode, 3.0V ≤ VIN ≤ 5.5V, Active,
No Load; ENL = AGND, FEN = ENS = IN
ENA = ENB = ENS = FEN = AGND
1
IIN(Q)
IN Operating Current
4
mA
5
IIN(SHDN)
TSD
IN Shutdown Current
Over-Temperature Shutdown
Threshold
Over-Temperature Shutdown
Hysteresis
1.0
µA
°C
140
15
TSD(HYS)
°C
Charge Pump Section
IOUT
VIN(TH_H)
OUT Maximum Output Current
600
500
mA
mV
Charge Pump Mode Hysteresis
Charge Pump Oscillator
Frequency
Address 0, Data 1
TA = 25°C
fOSC
2
MHz
BL1-BL6 Backlight LED Outputs
Address 0, Data 1; VIN - VF = 1.5V
Address 12, Data 2; VIN - VF = 1.5V
Address 0, Data 1; VIN - VF = 1.5V
18
20
30
22
IBL_(MAX)
ΔI(BL_)
BL1-BL6 Maximum Current
mA
%
2
BL1-BL6 Current Matching
1.0
BL1-BL6 Charge Pump Mode
Transition Threshold
FL1-FL2 Flash LED Outputs
VBL_(TH)
150
300
300
mV
IFL_(MAX)
ΔI(FL_)
FL1-FL2 Maximum Current
Address 4, Data 1; VIN - VF = 1.5V
Address 4, Data 1; VIN - VF = 1.5V
270
330
4.0
mA
%
2
FL1-FL2 Current Matching
FL1-FL2 Charge Pump Mode
Transition Threshold
VFL_(TH)
mV
ENS, FEN Logic Control
VENS(L)
VENS(H)
ENS, FEN Input Low Threshold
ENS, FEN Input High Threshold
0.4
V
V
1.4
IENS, IFEN ENS, FEN Input Leakage Current VENS or VFEN = VIN = 5V
ENS, FEN Serial Interface
-1.0
1.0
75
µA
tENS(LOW)
VIN ≥ 3.3V
0.3
µs
ns
µs
Low Time
tENS(HI_MIN)
,
ENS, FEN Serial Interface
50
tENS(HI_MIN) Minimum High Time
t
ENS(HI_MAX), ENS, FEN Serial Interface
tENS(HI_MAX) Maximum High Time
VIN ≥ 3.3V
75
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.
2846.2007.08.1.0
5
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
1
Electrical Characteristics
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)
tFEN(OFF)
tENS(LAT)
tFEN(LAT)
,
ENS, FEN Off Timeout
500
500
µs
µs
,
ENS, FEN Serial Interface
Latch Timeout
Linear Regulators
VFBA, VFBB Feedback Voltage Tolerance
IOUT = 1mA to 200mA
1.17 1.2
1.23
200
V
ENA = ENB = IN, ENS = AGND
ENA = IN, ENB = AGND or ENA =
AGND, ENB = IN, ENS = AGND
IIN
Ground Pin Current
µA
150
IOUTA(MAX)
IOUTB(MAX)
,
OUTA, OUTB Maximum Load
Current
200
150
50
mA
mV
dB
VOUTA(DO)
,
OUTA, OUTB Dropout Voltage
IOUT = 150mA
300
0.4
VOUTB(DO)
PSRRA,
PSRRB
OUTA, OUTB Power Supply
Rejection Ratio
ENA, ENB Voltage Low Threshold
ENA, ENB Voltage High Threshold
ENA, ENB Enable Delay
IOUT = 10mA, CREF = 10nF, 1kHz
VEN (L)
V
V
µs
_
VEN (H)
1.4
15
_
tEN (DLY)
REF = Open
_
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.
6
2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Typical Characteristics
Backlight Efficiency vs. Input Voltage
Flash Efficiency vs. Input Voltage
100
100
72mA/ch
90
20mA/ch
90
80
70
60
50
40
30
150mA/ch
80
70
60
50
10.2mA/ch 1.6mA/ch
40
30
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Input Voltage (V)
Flash Current Matching vs. Temperature
Backlight Current Matching vs. Temperature
(150mA/Ch; Data 6)
(20mA/ch; Data 1)
170
165
160
155
150
145
140
135
130
21.0
20.5
20.0
19.5
19.0
18.5
-40
-15
10
35
60
85
-40
-15
10
35
60
85
Temperature (°C)
Temperature (°C)
Turn On to 1.5X Mode Backlight
Turn On to 1X Mode Backlight
(30mA/ch; Data 1; VIN = 3.4V)
(30mA/ch; Data 1; VIN = 4.2V)
VEN
(2V/div)
VEN
(2V/div)
0V
0V
0V
VOUT
0V
0V
VOUT
(2V/div)
(2V/div)
VSINK
(500mV/div)
VSINK
(500mV/div)
0V
IIN
0A
IIN
0A
(200mA/div)
(200mA/div)
Time (200µs/div)
Time (200µs/div)
2846.2007.08.1.0
7
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Typical Characteristics
Turn On to 2X Mode Backlight
Turn Off from 1.5X Mode Backlight
(30mA/ch; Data 1; VIN = 2.7V)
(30mA/ch; Data 1)
VEN
(2V/div)
VEN
(2V/div)
0V
0V
0V
VOUT
VOUT
(2V/div)
(2V/div)
VSINK
(500mV/div)
0V
0A
0V
IIN
(200mA/div)
IIN
0A
(200mA/div)
Time (200µs/div)
Time (100µs/div)
BENS, FENS Low Threshold Voltage
vs. Input Voltage
BENS, FENS High Threshold Voltage
vs. Input Voltage
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
-40°C
-40°C
25°C
85°C
85°C
25°C
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Input Voltage (V)
BENS, FENS Latch Timeout vs. Input Voltage
BENS, FENS Off Timeout vs. Input Voltage
300
260
240
260
220
180
140
100
25°C
220
25°C
-40°C
200
-40°C
180
85°C
160
25°C
140
120
100
80
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Input Voltage (V)
8
2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Typical Characteristics
LDOs A and B Load Regulation
LDOs A and B Turn On Characteristic
1.0
0.5
VEN
(2V/div)
0V
0V
OUTA
OUTB
0.0
VOUT
(500mV/div)
-0.5
-1.0
0.1
1
10
100
1000
Time (50µs/div)
Load Current (mA)
LDOs A and B Output Voltage
vs. Temperature
LDOs A and B Load Regulation
1.5
1.0
0.5
1
0.5
0
OUTA
OUTB
0.0
-0.5
-1
-0.5
-1.0
0.1
-1.5
-40
1
10
100
1000
-15
10
35
60
85
Load Current (mA)
Temperature (°C)
LDOs A and B Dropout Characteristics
LDOs A and B Line Transient Response
(10mA Load)
3.2
3.0
2.8
2.6
2.4
2.2
2.0
IOUT = 100mA
VIN = 3.6V
VIN
(250mV/div)
VIN = 3.1V
IOUT = 200mA
VOUT
(AC Coupled)
(20mV/div)
2.7
2.8
2.9
3.0
3.1
3.2
Time (50µs/div)
Input Voltage (V)
2846.2007.08.1.0
9
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Typical Characteristics
LDOs A and B Load Transient Response
(10mA to 200mA Load Step)
IOUT = 200mA
IOUT
(100mA/div)
VOUT
(AC Coupled)
(100mV/div)
Time (50µs/div)
10
2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Functional Block Diagram
IN
IN
C1+
OUTA
FBA
LDO A
LDO B
C1-
1x/1.5x/2x
Charge Pump
C2+
OUTB
FBB
C2-
ENA
ENB
To LDO A
To LDO B
1.2V
VREF
REF
OUT
BL1
BL2
BL3
BL4
ENS
FEN
Control
Logic
BL5
BL6
CT
FSET
FL1
FL2
AGND PGND
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.
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.
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.
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-
The backlight and flash LED current levels are
2
dynamically controllable by the AS Cwire single-wire
2846.2007.08.1.0)
11
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
interface. The backlight section has multiple current
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.
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 280kΩ up to
1MΩ. Calculate the flash programming resistor
value using the equation:
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.
280k · 300mA
2
RFSET
=
Ω
AS Cwire Serial Interface Addressing
IFMAX
ENS
where IFMAX is the maximum flash LED current in mA.
Rising
Address Edges
Function
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.
0
1
17
18
Backlight Current BL1-BL6
Main Backlight Current
BL1-BL5
2
3
4
5
19
20
21
22
Sub Backlight Current BL6
Low Current Backlight
Flash Current FL1, FL2
Independent Flash On/Off
Control
Maximum Backlight Current
(Main and Sub)
Backlight Independent
Control
BL3-BL6 On/Off Control
BL1/BL2 On/Off Control
2
AS Cwire Serial Interface
12
15
29
32
The AAT2846 is dynamically programmable by the
2
2
AS Cwire single-wire interface. AS Cwire records
rising edges detected at the ENS pin to address
2
and load the data registers. AS Cwire latches data
Sub-2
Sub-3
19
20
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
2
Table 1: AS Cwire Serial Interface Addressing.
4
number of pulses is 2 or 16, so that Address 0 is
Backlight Current Control (Address 0-3)
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
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.
12
2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Address
Data
THI
TLAT
TLO
TLAT
EN/SET
Address
1
2
17
0
18
1
2 . . .
n ≤ 16
1
0
0
n
Data Reg 1
Data Reg 2
2
Figure 1: AS Cwire Serial Interface Timing.
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.
Data
1
2
3
4
5
6
7
8
30mA Max (mA) 20mA Max (mA)
30.0
27.9
26.1
24.2
21.0
19.2
17.3
15.0
12.7
10.9
8.1
20.0
19.0
17.8
16.5
14.3
13.0
11.8
10.2
8.5
9
Main
Sub
Current
(µA)
10
11
12
13
14
15
16
7.3
5.4
Data
Current On Current On
1
2
No
No
No
No
0
0
6.2
4.1
4.4
2.9
3
No
No
0
3.5
2.2
4
No
No
0
2.6
1.6
5
6
7
8
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Yes
Yes
95
0
0
500
950
1900
95
500
950
1900
95
Table 2: Data Code for Backlight Current Level
,
Address 0-2.
9
35.0
30.0
25.0
20.0
10
11
12
13
14
15
16
500
950
1900
30mA (Full Scale)
15.0
10.0
5.0
20mA (Full Scale)
0.0
Table 3: Data Code for Low-Level Backlight
Current, Address 3, FS = 20mA range.
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16
Data Code
Figure 2: Data Code for Address 0-2 vs.
Backlight Current Level
.
2846.2007.08.1.0
13
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Flash Current FL1, FL2 (Address 4)
Independent Flash ON/OFF Control
(Address 5)
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.
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.
Flash LED Current
Data
(% of Maximum)
Data
FL1
FL2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
100
87
77
66
58
50
44
39
35
30
27
24
20
17
16
14
1
2
3
4
Off
Off
On
On
Off
On
Off
On
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)
Table 4: Data Code for the Flash Current
Control, Address 4.
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.
120
IFLED = 100%
at Data 1
100
80
60
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.
IFLED = 14%
40
at Data 16
20
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16
Data Code
Data
1
2
Maximum Current
Figure 3: Data Code for Address 4 vs.
percentage of Flash Current Level.
20mA
30mA
Table 6: Data Code for the Maximum Current
Settings, Address 12.
14
2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
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.
Data
1
2
3
4
5
6
7
8
BL6
BL5
BL4
BL3
Off
Off
Off
Off
Off
Off
Off
Off
On
On
On
On
On
On
On
On
Off
Off
Off
Off
On
On
On
On
Off
Off
Off
Off
On
On
On
On
Off
Off
On
On
Off
Off
On
On
Off
Off
On
On
Off
Off
On
On
Off
On
Off
On
Off
On
Off
On
Off
On
Off
On
Off
On
Off
On
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
9
2
the A SCwire's tOFF latch time.
10
11
12
13
14
15
16
Data
Individual Backlight Control
8
On
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.
Table 8: Data Code for BL3-BL6
On/Off Control, Sub-Address 2.
Data
BL2
BL1
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.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Off
Off
Off
Off
Off
Off
Off
Off
On
On
On
On
On
On
On
On
Off
Off
Off
Off
On
On
On
On
Off
Off
Off
Off
On
On
On
On
The LDO enables are always independent of
2
AS Cwire programming.
Flash LED Current Control
The flash LEDs are driven through current sinks
FL1 and FL2. There are two ways to drive the flash
2
Table 9: : Data Code for BL1 and BL2
On/Off Control, Sub-Address 3.
LEDs: either through the AS Cwire 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.
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-
2846.2007.08.1.0
15
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
centage of the maximum current set by an external
Flash Protection Timer
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.
The AAT2846 includes a protection timer set by the
capacitor CT connected from CT to 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:
TF = 10 · CT
Flash Strobe Input
where TF is in seconds and CT is in µF.
For example: if CT = 0.1µF:
The AAT2846 features an active high flash enable
2
input, FEN, that overrides the AS Cwire 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 CT capacitor is such that
the flash LEDs remain within their power dissipa-
TF = 10 · 0.1μF
= 1s
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.
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.
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.
16
2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Applications Information
R2 Standard 1% Values (R1 = 120K)
VOUT (V)
R2 (Ω)
LDO Output Voltage Programming
2.8
2.5
2.0
1.8
1.5
160K
130K
79.6K
60.4K
30.1K
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.
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:
OUT(A/B)
VOUT(A/B)
R2(A/B)
R1(A/B)
FB(A/B)
VREF(A/B) = 1.2V
300mA · 280kΩ
=
ILED(MAX)
RFSET
This is illustrated in Figure 4.
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.
450
400
350
300
250
200
150
100
50
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.
0
100 200 300 400 500 600 700 800 900 1000 1100
RFSET (kΩ)
R1(VOUT - 1.2V)
R2 =
1.2V
Figure 4: Maximum Flash LED Current
vs. RFSET
.
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.
2846.2007.08.1.0
17
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
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.
VF · ILED
=
VIN · 1.5IIN 1.5 · VIN
VF
η =
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:
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.
POUT
η =
PIN
VF · ILED
VF
η =
=
VIN · 2IIN 2 · VIN
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:
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.
VF · ILED
VIN · IIN
VF
η =
≈
VIN
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.
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.
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.
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.
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:
18
2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
The junction-to-ambient thermal resistance (θJA) for
Equivalent Series Resistance
the connection can be significantly reduced by fol-
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.
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.
Ceramic Capacitor Materials
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.
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.
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.
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.
Figure 5: Example PCB Layout.
2846.2007.08.1.0
19
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Evaluation Board Layout
Figure 6: AAT2846 Evaluation Board
Figure 7: AAT2846 Evaluation Board
Layout Bottom Side.
Layout Top Side.
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.
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.
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+).
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 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.
20
2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
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.
Toggle ON/OFF the backlighting section. Set the brightness level using the DATA button
(defaults to Data 1).
LIGHT
LIGHT+DATA
MOVIE
Decrement the brightness setting for backlight mode. Hold down to auto-cycle.
Toggle ON/OFF movie mode illumination. Set the brightness level using the DATA but-
ton (defaults to Data 10).
MOVIE+DATA
FLASH
Decrement the brightness setting for movie mode. Hold down to auto-cycle.
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).
Toggle ON/OFF the LDOs.
FLASH+DATA
LIGHT+MOVIE+FLASH
Reset. Clear all data and bring all enable lines low.
Table 11: AAT2846 Evaluation Board User Interface.
Evaluation Board Schematics
VOUT
DC+
D1
D2
D3
D4
D5
D6
D7
D8
VIN
J1
C12
1
2
3
280K yields
300mA/chnl
max flash
100μF
optional 100μF
lab supply bypass
R10
280K
U1
ENLA
ENFL
1
2
3
4
5
6
7
21
20
19
18
17
16
15
D3
F2
ENBL
ENLB
D2
ENS
PGND
IN
D1
AGND
CT
C4
4.7μF
C2-
C2
1.0μF
CREF
FBB
C2+
ENB
C8
0.1μF
_
CTRL CT
C9
0.1μF
8
9
10 11 12 13 14
VOUT
C3
C6
R11
160K
OUTB
2.2μF
C5
2.2μF
C1
1.0μF
2.2μF
Programmed for 2.8V
output by default
R12
120K
OUTA
C7
2.2μF
R13
60.4K
Programmed for 1.8V
output by default
R14
120K
Figure 8: AAT2846 Section Schematic
2846.2007.08.1.0
21
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
U3
VIN
J2
J3
J4
J5
ENBL
ENFL
ENLA
ENLB
AAT4290
1
2
3
4
8
7
6
5
ENBL
ENFL
ENLA
ENLB
IN
OUT2
OUT1
OUT3
OUT4
OUT5
C11
0.1μF
EN/SET GND
R6
R7
R8
R9
100K 100K 100K 100K
VIN
VIN
R1 R2 R3 R4
1K 1K 1K 1K
U2
C10
0.1μF
R5
1
8
7
6
5
VDD
2
VSS
GP0
GP1
GP2
330
GP5
3
DATA
SW1
SW2
SW3
SW4
GP4
4
LED7
RED
GP3
LIGHT
MOVIE
FLASH
PIC12F675
CTRL_CT
DC-
Figure 9: MCU and I/O Expander Section Schematic
22
2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Evaluation Board Component Listing
Component
Part#
Description
Manufacturer
U1
AAT2846INJ-EE-T1
High Eff. 1X/1.5X/2X CP for White LED,
Dual LDO
AnalogicTech
U2
U3
PIC12F675
AAT4290IJS-1-T1
LW M673
LXCL-PWF1
GRM18x
GRM18x
GRM18x
GRM18x
TAJBx
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
PRPN401PAEN
CMD15-21SRC/TR8
PTS645TL50
8-bit CMOS, FLASH MCU; 8-pin PDIP
I/O Expander
Mini TOPLED White LED; SMT
Luxeon Flash LED
1.0µF, 10V, X5R, 0603, Ceramic
2.2µF, 10V, X5R, 0603, Ceramic
4.7µF, 10V, X5R, 0603, Ceramic
0.1µF, 16V, X7R, 0603, Ceramic
100µF, 10V, 10µA, Tantalum
1K, 5%, 1/4W; 1206
Microchip
AnalogicTech
OSRAM
Lumileds
Murata
Murata
Murata
Murata
AVX
Vishay
Vishay
Vishay
Vishay
Vishay
Vishay
Vishay
D1-D6
D7, D8
C1, C2
C3-C7
C4
C8-C11
C12
R1-R4
R5
R6-R9
R10
R11
R12, R14
R13
J1-J5
LED7
SW1-SW4
330, 5%, 1/4W; 1206
100K, 5%, 1/10W; 0603
280K, 1%, 1/10W; 0603
160K, 1%, 1/10W; 0603
120K, 1%, 1/10W; 0603
60.4K, 1%, 1/10W; 0603
Conn. Header, 2mm Zip
Red LED; 1206
Sullins Electronics
Chicago Miniature Lamp
ITT Industries
Switch Tact, SPST, 5mm
2846.2007.08.1.0
23
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
Ordering Information
1
2
Package
TQFN44-28-0.4
Marking
UPXYY
Part Number (Tape and Reel)
AAT2846INJ-EE-T1
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.
3
Package Information
TQFN44-28-0.4
Pin 1 Dot
by Marking
Detail "A"
C0.3
4.000 0.050
2.600 0.050
Bottom View
Top View
0.400 0.050
0.430 0.050
0.750 0.050
0.203 REF
0.050 0.050
Side View
Pin 1 Indicator
Detail "A"
All dimensions in millimeters.
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.
24
2846.2007.08.1.0
AAT2846
High Current Charge Pump with Dual LDO
for Backlight and Flash Applications
© 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.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
2846.2007.08.1.0
25
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