Analogic AAT2846 High current charge pump with dual ldo for backlight and flash application Datasheet

PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
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 driven 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™) single-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
matching is 1% for uniform display brightness, and flash
current matching is 4% for uniform power dissipation.
• 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
The AAT2846 offers two high-performance low-noise
MicroPower™ low dropout (LDO) linear regulators. 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 batteryoperated applications.
The AAT2846 is equipped with built-in short-circuit and
over-temperature protection. The soft start circuitry 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.
Applications
• Camera-Enabled Mobile Devices
• Digital Still Cameras
• Multimedia Mobile Phones
Typical Application
C2
1µF
C1
1µF
C1+
C1- C2+
IN
CIN
4.7µF
VBAT
IN
AAT2846
ENABLE/SET
ENS
EN_FLASH
FEN
CT
CT
0.1µF
FSET
RFSET
280k
REF
CBYP
0.1µF
EN_LDOA
EN_LDOB
VOUT
COUT
2.2µF
BL1
BL2
BL3
BL4
BL5
BL6
FL1
FL2
OUTA
VOUT LDOA
R2A
FBA
COUTA
R1A
ENA
ENB
AGND
2846.2008.03.1.1
C2-
OUT
VOUT LDOB
OUTB
R2B
FBB
PGND
www.analogictech.com
COUTB
R1B
1
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
Pin Descriptions
Pin #
Symbol
1
BL3
2
BL2
3
BL1
4
AGND
5
CT
6
REF
7
FBB
8
OUTB
9, 18
IN
10
FBA
11
OUTA
12
13
C1C1+
14
OUT
15
ENB
16
17
19
C2+
C2PGND
20
ENS
21
FL2
22
FL1
23
FEN
24
FSET
25
BL6
26
BL5
27
ENA
28
BL4
EP
2
Description
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.
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 larger 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-.
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.
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-.
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 backlight and is the
AS2Cwire input to serially control the backlight and movie-mode flash LED brightness.
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.
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.
www.analogictech.com
2846.2008.03.1.1
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
Pin Configuration
TQFN44-28
(Top View)
FL1
FEN
FSET
BL6
BL5
ENA
BL4
28
BL3
BL2
BL1
AGND
CT
REF
FBB
27
26
25
24
23
22
1
21
2
20
3
19
4
18
5
17
6
16
7
15
8
9
10
11
12
13
14
FL2
ENS
PGND
IN
C2C2+
ENB
OUT
C1+
C1OUTA
FBA
IN
OUTB
Absolute Maximum Ratings1
Symbol
TJ
TLEAD
Description
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
PGND Voltage to AGND
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
Units
-0.3 to 6.0
V
-0.3 to VIN + 0.3
V
-0.3 to 0.3
-40 to 150
300
V
°C
°C
Value
Units
2
50
W
°C/W
Thermal Information2
Symbol
PD
θJA
Description
Maximum Power Dissipation3
Maximum Thermal Resistance
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 6.25mW/°C above 25°C ambient temperature.
2846.2008.03.1.1
www.analogictech.com
3
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
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
VIN
IIN(Q)
Description
Conditions
IN Operating Voltage Range
IN Operating Current
∆I(BL_)
BL1-BL6 Maximum Current
BL1-BL6 Current Matching
BL1-BL6 Charge Pump Mode Transition
Threshold
FL1-FL2 Flash LED Outputs
IFL_(MAX)
FL1-FL2 Maximum Current
∆I(FL_)
FL1-FL2 Current Matching2
FL1-FL2 Charge Pump Mode Transition
VFL_(TH)
Threshold
ENS, FEN Logic Control
VENS(L)
ENS, FEN Input Low Threshold
ENS, FEN Input High Threshold
VENS(H)
IENS, IFEN
ENS, FEN Input Leakage Current
tENS(LOW)
ENS, FEN Serial Interface Low Time
tENS(HI_MIN),
ENS, FEN Serial Interface Minimum High Time
tENS(HI_MIN)
tENS(HI_MAX),
ENS, FEN Serial Interface Maximum High Time
tENS(HI_MAX)
tENS(OFF),
ENS, FEN Off Timeout
tFEN(OFF)
tENS(LAT),
ENS, FEN Serial Interface Latch Timeout
tFEN(LAT)
2
Typ
2.7
IIN(SHDN)
IN Shutdown Current
TSD
Over-Temperature Shutdown Threshold
TSD(HYS)
Over-Temperature Shutdown Hysteresis
Charge Pump Section
IOUT
OUT Maximum Output Current
VIN(TH_H)
Charge Pump Mode Hysteresis
fOSC
Charge Pump Oscillator Frequency
BL1-BL6 Backlight LED Outputs
IBL_(MAX)
Min
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
Units
5.5
V
1
4
1.0
18
140
15
µA
°C
°C
600
500
2
mA
mV
MHz
20
30
22
1.0
150
Address 4, Data 1; VIN - VF = 1.5V
Address 4, Data 1; VIN - VF = 1.5V
270
300
330
4.0
1.0
75
50
VIN ≥ 3.3V
%
mA
%
mV
0.4
1.4
-1.0
0.3
mA
mV
300
VENS or VFEN = VIN = 5V
VIN ≥ 3.3V
mA
5
Address 0, Data 1
TA = 25°C
Address 0, Data 1; VIN - VF = 1.5V
Address 12, Data 2; VIN - VF = 1.5V
Address 0, Data 1; VIN - VF = 1.5V
Max
V
V
µA
µs
ns
75
µs
500
µs
500
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.
2. Current matching is defined as the deviation of any sink current from the average of all active channels.
4
www.analogictech.com
2846.2008.03.1.1
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
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
IOUT = 1mA to 200mA
ENA = ENB = IN, ENS = AGND
1.17
1.2
1.23
200
V
Linear Regulators
VFBA, VFBB
IOUTA(MAX),
IOUTB(MAX)
VOUTA(DO),
VOUTB(DO)
PSRRA,
PSRRB
VEN_(L)
VEN_(H)
tEN_(DLY)
Feedback Voltage Tolerance
OUTA, OUTB Maximum Load Current
200
OUTA, OUTB Dropout Voltage
IOUT = 150mA
OUTA, OUTB Power Supply Rejection Ratio
IOUT = 10mA, CREF = 10nF, 1kHz
ENA, ENB Voltage Low Threshold
ENA, ENB Voltage High Threshold
ENA, ENB Enable Delay
mA
150
300
50
dB
0.4
1.4
REF = Open
15
mV
V
V
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.
2846.2008.03.1.1
www.analogictech.com
5
PRODUCT DATASHEET
AAT2846
ChargePumpTM
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
20mA/ch
80
70
60
50
72mA/ch
150mA/ch
90
Efficiency (%)
Efficiency (%)
90
10.2mA/ch 1.6mA/ch
80
70
60
50
40
40
30
30
2.7
3.1
3.5
3.9
4.3
4.7
5.1
2.7
5.5
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
21.0
LED Current (mA)
LED Current (mA)
165
20.5
20.0
19.5
19.0
18.5
-40
160
155
150
145
140
135
-15
10
35
60
85
130
-40
-15
10
Turn On to 1X Mode Backlight
Turn On to 1.5X Mode Backlight
(30mA/ch; Data 1; VIN = 4.2V)
(30mA/ch; Data 1; VIN = 3.4V)
VEN
(2V/div)
0V
VOUT
(2V/div)
0V
VOUT
(2V/div)
VSINK
(500mV/div)
0V
VSINK
(500mV/div)
IIN
(200mA/div)
IIN
(200mA/div)
0A
Time (200µs/div)
6
60
85
Temperature (°C)
Temperature (°C)
VEN
(2V/div)
35
0V
0V
0V
0A
Time (200µs/div)
www.analogictech.com
2846.2008.03.1.1
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
Typical Characteristics
VEN
(2V/div)
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)
0V
VOUT
(2V/div)
0V
VSINK
(500mV/div)
0V
VOUT
(2V/div)
0V
0V
IIN
(200mA/div)
IIN
(200mA/div)
0A
0A
Time (100µs/div)
Time (200µs/div)
BENS, FENS High Threshold Voltage
vs. Input Voltage
BENS, FENS Low Threshold Voltage
vs. Input Voltage
1.4
1.4
1.3
VBENS(L), VFENS(L) (V)
VBENS(H), VFENS(H) (V)
1.3
-40°C
1.2
1.1
1.0
0.9
0.8
25°C
0.7
85°C
1.2
-40°C
1.1
1.0
0.9
0.8
0.7
25°C
0.6
0.6
0.5
0.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
2.7
5.5
3.1
3.5
Input Voltage (V)
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
BENS, FENS Latch Timeout vs. Input Voltage
BENS, FENS Off Timeout vs. Input Voltage
300
260
240
220
VBENS(H), VFENS(H) (V)
TBENS(LAT), TFENS(LAT) (µs)
85°C
25°C
200
-40°C
180
160
25°C
140
120
260
25°C
-40°C
220
85°C
180
140
100
80
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
100
2.7
Input Voltage (V)
2846.2008.03.1.1
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
www.analogictech.com
7
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
Typical Characteristics
LDOs A and B Turn On Characteristic
LDOs A and B Load Regulation
VEN
(2V/div)
Output Voltage Error (%)
1.0
0V
VOUT
(500mV/div)
0V
0.5
OUTA
0.0
OUTB
-0.5
-1.0
0.1
1
10
Time (50µs/div)
3.2
1
3.0
Output Voltage (V)
Output Voltage (%)
LDOs A and B Dropout Characteristics
1.5
0.5
0
-0.5
-1
-15
10
35
1000
Load Current (mA)
LDOs A and B Output Voltage
vs. Temperature
-1.5
-40
100
60
85
IOUT = 100mA
2.8
2.6
IOUT = 200mA
2.4
2.2
2.0
2.7
2.8
Temperature (°C)
2.9
3.0
3.1
3.2
Input Voltage (V)
LDOs A and B Line Transient Response
LDOs A and B Load Transient Response
(10mA Load)
(10mA to 200mA Load Step)
VIN = 3.6V
IOUT = 200mA
IOUT
(100mA/div)
VIN
(250mV/div)
VIN = 3.1V
VOUT
(AC Coupled)
(100mV/div)
VOUT
(AC Coupled)
(20mV/div)
Time (50µs/div)
8
Time (50µs/div)
www.analogictech.com
2846.2008.03.1.1
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
Functional Block Diagram
IN
IN
C1+
C1C2+
OUTA
LDO A
1x/1.5x/2x
Charge Pump
OUTB
C2-
ENA
ENB
FBA
LDO B
To LDO A
FBB
1.2V
VREF
REF
To LDO B
OUT
BL1
BL2
BL3
ENS
FEN
BL4
Control
Logic
BL5
BL6
CT
FSET
FL1
FL2
AGND PGND
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 voltages as low as 1.2V.
LED Drivers
The LEDs are driven from an internal charge pump that,
depending on the battery voltage and LED forward voltage, drives LEDs directly from the supply voltage (1X or
bypass mode) or steps up the supply 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
2846.2008.03.1.1
more compact solution than typical inductor-based stepup converter 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 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 500mV mode-transition
hysteresis that prevents the charge pump from oscillating between charge pump modes.
www.analogictech.com
9
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
AS2Cwire Serial Interface
The backlight and flash LED current levels are dynamically controllable by the AS2Cwire single-wire 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 supported by the device is
300mA/channel, or 600mA total. This corresponds to a
280K set resistor value.
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 differentiated by the number of ENS
rising edges. Since the data registers are 4 bits each, the
differentiating number of pulses is 24 or 16, so that
Address 0 is identified by 17 rising edges, Address 1 by
18 rising 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 channels BL1-BL6 will turn-on
according to the number of data edges applied.
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:
RFSET =
280k · 300mA
Ω
IFMAX
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 determines that the current sink
is not used or that the LED is shorted. In either case, the
controller turns off the affected current sink.
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 shutdown, the data
and address registers are reset to 0.
Address
Data
T HI
T LO
TLAT
TLAT
EN/SET
1
Address
2
17
18
1
0
2...
n ≤ 16
1
Data Reg 1
0
Data Reg 2
0
n
Figure 1: AS2Cwire Serial Interface Timing.
10
www.analogictech.com
2846.2008.03.1.1
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
AS2Cwire Serial Interface Addressing
0
1
2
3
4
5
17
18
19
20
21
22
12
29
15
Sub-2
Sub-3
32
19
20
30.0
Function
25.0
Backlight Current BL1-BL6
Main Backlight Current BL1-BL5
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
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 programmed 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.
Data
30mA Max (mA)
20mA Max (mA)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
30.0
27.9
26.1
24.2
21.0
19.2
17.3
15.0
12.7
10.9
8.1
6.2
4.4
3.5
2.6
0
20.0
19.0
17.8
16.5
14.3
13.0
11.8
10.2
8.5
7.3
5.4
4.1
2.9
2.2
1.6
0
Table 2: Data Code for Backlight Current Level,
Address 0-2.
2846.2008.03.1.1
IBLED (mA)
Address
ENS Rising
Edges
35.0
20.0
30mA (Full Scale)
15.0
20mA (Full Scale)
10.0
5.0
0.0
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.
The AAT2846 incorporates additional circuitry that optimizes performance for exceptionally low backlight 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
Main Current
On
Sub Current
On
Current
(µA)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Yes
Yes
0
0
0
0
95
500
950
1900
95
500
950
1900
95
500
950
1900
Table 3: Data Code for Low-Level Backlight
Current, Address 3, FS = 20mA range.
www.analogictech.com
11
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
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.
Data
Flash LED Current
(% of Maximum)
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
IFLED (% of FL Maximum)
IFLED = 100%
at Data 1
80
60
IFLED = 14%
at Data 16
FL2
Off
Off
On
On
Off
On
Off
On
Table 5: Output Enable Control, Address 5.
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.
20
Data
Maximum Current
0
1
2
20mA
30mA
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16
Data Code
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
12
FL1
1
2
3
4
Maximum Backlight Current
(Address 12)
120
40
Data
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
setting is always reset to Data 1 when the flash timer
expires or when FEN is strobed low.
Table 4: Data Code for the Flash Current Control,
Address 4.
100
flash channel current level, write to Address 5 to enable
a single channel or both channels according to Table 5.
Table 6: Data Code for the Maximum Current
Settings, Address 12.
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.
www.analogictech.com
2846.2008.03.1.1
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
To enable independent channel control mode, write Data
8 to Address 15. To exit individual mode control, the
AAT2846 state machine can be reset by strobing ENS low
and holding ENS low longer than the AS2Cwire’s tOFF latch
time.
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 settings listed in the
tables, any combination of backlighting 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 disabled
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 operated 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.
Flash/Movie Mode Operation
The flash LED current level is set via the serial interface
according to a logarithmic scale where each code is
1.2dB lower than the previous code as a percentage of
the maximum current set by an external resistor, RFSET
from FSET to AGND. Flash LED current is set between
2846.2008.03.1.1
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 channels can be connected in parallel to drive
the sum of the two channel currents into a single LED.
Data
BL6
BL5
BL4
BL3
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
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
Table 8: Data Code for BL3-BL6
On/Off Control, Sub-Address 2.
Data
BL2
BL1
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
Table 9: Data Code for BL1 and BL2
On/Off Control, Sub-Address 3.
www.analogictech.com
13
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
Flash/Movie Mode Operation
Flash Protection Timer
The flash LED current level is set via the serial interface
according to a logarithmic scale where each code is
1.2dB lower than the previous code as a percentage of
the maximum current set by an external resistor, RFSET
from FSET to AGND. Flash LED current 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 channels 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 rating should a data error
occur in the controller. The flash protection time, TF, is
calculated by the following equation:
where TF is in seconds and CT is in µF.
For example: if CT = 0.1µF:
Flash Strobe Input
The AAT2846 features an active high flash enable input,
FEN, that overrides the AS2Cwire programming and
drives both flash outputs, FL1 and FL2, at the maximum
current set by the flash current setting resistor RFSET.
This signal also triggers an internal protection timer.
When the FEN input is strobed low, the flash current is
turned off independent 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 dissipation 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.
14
TF = 10 · CT
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 voltage 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 current allows
the regulator to maintain output voltage regulation.
Each LDO regulator can supply up to 200mA continuous
current to the load. They include current limiting and
thermal overload protection to prevent damage to the
load or to the LDOs.
www.analogictech.com
2846.2008.03.1.1
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
Applications Information
Altering the Maximum
Flash LED Current Level
LDO Output Voltage Programming
RFSET determines the maximum LED current level at each
of the F1 and F2 flash LED outputs. In the typical application, selecting RFSET = 280K results in 300mA/ch LED
current. From this reference point, the maximum current
level can be modified by calculating an alternative RFSET
value:
The output voltages for LDOA and LDOB are programmed
by an external resistor divider network. As shown below,
the selection of R1 and R1 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 capacitance to become a
larger factor in circuit performance whereas lower resistor values increase bias current and decrease efficiency.
OUT(A/B)
RFSET =
300mA · 280kΩ
ILED(MAX)
This is illustrated in Figure 4.
VOUT(A/B)
450
400
R2(A/B)
350
VREF(A/B) = 1.2V
IFLED (mA)
FB(A/B)
R1(A/B)
300
250
200
150
100
50
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, calculate R1 according
to the equation below. An example 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 information, R1
is calculated from the equation below.
R2 =
R1(VOUT - 1.2V)
1.2V
0
100
R2 (Ω)
160K
130K
79.6K
60.4K
30.1K
Table 10: Example Output Voltages and
Corresponding Resistor Values
2846.2008.03.1.1
400
500
600
700
800
900
1000 1100
RFSET (kΩ
Ω)
Figure 4: Maximum Flash LED Current
vs. RFSET.
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.
The AAT2846 power conversion efficiency depends on
the charge pump mode. By definition, device efficiency
is expressed as the output power delivered to the LEDs
divided by the total input power consumed.
η=
R2 Standard 1% Values (R1 = 120K)
2.8
2.5
2.0
1.8
1.5
300
Device Power Efficiency
The result is R1 = 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 R1 = 60.4K.
Example output voltages and corresponding resistor
values are provided in Table 11.
VOUT (V)
200
POUT
PIN
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 passing the input supply directly
to the output. By simplifying the conditions such that the
LEDs have uniform VF, the power conversion efficiency
can be approximated by:
www.analogictech.com
15
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
η=
VF
VF · ILED
≈
VIN · IIN
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.
The AAT2846 further maintains optimized performance
and efficiency by detecting when the input voltage is not
sufficient to sustain LED drive current. The device automatically switches to 1.5X mode when the input voltage
drops too low in relation 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 efficiency is given by:
η=
VF
VF · ILED
=
VIN · 1.5IIN 1.5 · VIN
Similarly, when the input falls further, such that 1.5X
mode can no longer sustain LED drive current, 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 doubling of the input current. For ideal
conversion, the 2X mode efficiency is given by:
η=
VF
VF · ILED
=
VIN · 2IIN 2 · VIN
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 various load
types, the AAT2846 provides a high-current, 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 performance. 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.
16
Ceramic composition capacitors are highly recommended over all other types of capacitors for use with the
AAT2846. Ceramic capacitors offer many advantages
over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically has very low ESR, is
lowest cost, has a smaller PCB footprint, and is nonpolarized. Low ESR ceramic capacitors help maximize
charge pump transient response. Since ceramic capacitors are non-polarized, they are not prone to incorrect
connection damage.
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 composition, and ambient
temperature. Capacitor ESR is typically measured in milliohms for ceramic capacitors 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 values are usually composed of X7R, X5R, Z5U, or Y5V dielectric materials.
Large ceramic capacitors are often available in lowercost 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 material 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 performance,
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.
www.analogictech.com
2846.2008.03.1.1
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
The junction-to-ambient thermal resistance (θJA) for the
connection can be significantly reduced by following 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
close to the IC. Trace length should be
minimize path resistance and potential
input and output capacitors should also
close to the chip as possible.
be connected
kept short to
coupling. The
be placed as
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, consideration
must be given to the voltage levels. The externally
applied voltages cannot exceed the supply voltage 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.
Figure 5: Example PCB Layout.
2846.2008.03.1.1
www.analogictech.com
17
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
Button(s) Pushed
DATA
LIGHT
LIGHT+DATA
MOVIE
MOVIE+DATA
FLASH
FLASH+DATA
LIGHT+MOVIE+FLASH
Description
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).
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 button (defaults to Data 10).
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.
Reset. Clear all data and bring all enable lines low.
Table 11: AAT2846 Evaluation Board User Interface.
Evaluation Board Layout
Figure 6: AAT2846 Evaluation Board
Layout Top Side.
18
Figure 7: AAT2846 Evaluation Board
Layout Bottom Side.
www.analogictech.com
2846.2008.03.1.1
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
Evaluation Board Schematics
VOUT
DC+
D1
D2
D3
D4
D5
D6
D7
D8
VIN
J1
1
2
C12
100µF
3
280K yields
300mA/chnl
max flash
optional 100µF
lab supply bypass
R10
280K
22
23
24
25
26
U1
F1
FEN
D6
FSET
D5
ENA
D4
ENFL
27
28
ENLA
1
2
3
4
5
6
7
ENS
D1
PGND
AGND
IN
C2-
CREF
C2+
FBB
ENB
21
20
ENBL
19
18
17
16
C2
1.0µF
C4
4.7µF
15
OUT
C1-
9
C1+
IN
8
OUTA
CT
FBA
C9
0.1µF
C8
0.1µF
F2
D2
OUTB
CTRL _CT
D3
ENLB
10 11 12 13 14
VOUT
OUTB
Programmed for 2.8V
output by default
R11
160K
C6
2.2µF
C5
2.2µF
C3
2.2µF
C1
1.0µF
R12
120K
R13
60.4K
R14
120K
C7
2.2µF
OUTA
Programmed for 1.8V
output by default
Figure 8: AAT2846 Section Schematic.
2846.2008.03.1.1
www.analogictech.com
19
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
U3
AAT4290
VIN
C11
0.1µF
1
2
3
4
IN
OUT3
OUT2
OUT4
OUT1
OUT5
EN/SET GND
8
7
6
5
J2
ENBL
J3
ENFL
J4
ENLA
J5
ENLB
ENBL
ENFL
ENLA
ENLB
R6
R7
R8
R9
100K 100K 100K 100K
VIN
VIN
R1
1K
DATA
SW1
LIGHT
SW2
MOVIE
SW3
FLASH
SW4
R2
1K
R3
1K
R4
1K
U2
1
2
3
4
VDD
GP5
GP4
GP3
VSS
GP0
GP1
GP2
8
7
6
5
C10
0.1µF
R5
330
LED7
RED
PIC12F675
CTRL_CT
DC-
Figure 9: MCU and I/O Expander Section Schematic.
Evaluation Board Component Listing
20
Component
Part#
Description
Manufacturer
U1
AAT2846INJ-EE-T1
High Eff. 1X/1.5X/2X CP for White LED, Dual LDO
AnalogicTech
U2
U3
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
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
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
Switch Tact, SPST, 5mm
Microchip
AnalogicTech
OSRAM
Lumileds
Murata
Murata
Murata
Murata
AVX
Vishay
Vishay
Vishay
Vishay
Vishay
Vishay
Vishay
Sullins Electronics
Chicago Miniature Lamp
ITT Industries
www.analogictech.com
2846.2008.03.1.1
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TQFN44-28-0.4
UPXYY
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/about/quality.aspx.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
2846.2008.03.1.1
www.analogictech.com
21
PRODUCT DATASHEET
AAT2846
ChargePumpTM
High Current Charge Pump with Dual LDO for Backlight and Flash Applications
Package Information1
TQFN44-28-0.4
Pin 1 Dot
by Marking
C0.3
2.600 ± 0.050
4.000 ± 0.050
Detail "A"
4.000 ± 0.050
2.600 ± 0.050
Top View
Bottom View
0.400 ± 0.050
0.430 ± 0.050
0.750 ± 0.050
0.230 ± 0.050
0.203 REF
0.050 ± 0.050
Side View
Pin 1 Indicator
Detail "A"
All dimensions in millimeters.
1. 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.
Advanced Analogic Technologies, Inc.
3230 Scott Boulevard, Santa Clara, CA 95054
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 without notice. Except as provided in AnalogicTech’s terms and
conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty 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.
22
www.analogictech.com
2846.2008.03.1.1