AAT2861IMK-2-T1 [AAT]
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit; 背光/闪光LED驱动器和多个LDO照明管理单元
| 型号： | AAT2861IMK-2-T1 |
| 厂家： | 
ADVANCED ANALOG TECHNOLOGY, INC. |
| 描述： | Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit |
| 文件： | 总27页 (文件大小：3108K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
General Description
Features
The AAT2861 is a highly integrated charge pump-based
lighting management unit (LMU) offering eight LED
channels with three linear regulators optimized for sin-
gle-cell lithium-ion/polymer systems. The charge pump
provides power for all LED outputs; multiple backlight
and flash LED configurations are available. The backlight
LED outputs can be programmed up to 31mA each and
the flash LED output current can be programmed 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. A
programmable safety timer and separate flash control
input are included for easy flash control. Backlight cur-
rent matching is better than 3% for uniform display
brightness, and flash current matching is better than 5%
for uniform power dissipation.
• Input Voltage Range: 2.7V to 5.5V
•
•
AS2Cwire Serial Interface
Tri-Mode Charge Pump
Drives up to Eight LEDs (Backlight/Flash)
Programmable Backlight Current Settings
▪
•
•
31mA Maximum Current per Channel
32 Linear Current Settings
Independent Main/Sub Settings
Programmable Fade-In and Fade-Out
▪
▪
▪
▪
Programmable Flash Current
600mA Total Flash Current
16 Linear Current Settings
1- or 2-Channel Configuration
▪
▪
▪
•
•
•
1MHz Switching Frequency
Automatic Soft-Start
Three Linear Low Dropout Regulators
300mA Output Current
150mV Dropout
Programmable Output Voltage from 1.2V to 3.3V
Output Auto-Discharge for Fast Shutdown
▪
▪
The AAT2861 also offers three high-performance low-
noise MicroPower™ LDO linear regulators. The regulators
output voltages are set through the AS2Cwire serial
interface. Each LDO can supply up to 300mA load cur-
rent and ground-pin current is only 80μA, making the
AAT2861 ideal for battery-operated applications.
▪
▪
•
•
•
•
Built-In Thermal Protection
Automatic Soft Start
-40°C to +85°C Temperature Range
TQFN34-24 Package
The AAT2861 is available in a Pb-free, space-saving
TQFN34-24 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
CF1
1µF
CF2
1µF
WLEDs
OSRAM LW M673
or equivalent
C1+ C1- C2+ C2-
IN OUT
VOUT
Flash LEDs
Lumiled LXCL-PWF1
VBAT
3.6V
CIN
2.2µF
COUT
2.2µF
or equivalent
AAT2861-x
IN
BL1
BL2
BL3
BL4
BL5
BL6
EN/SET
FL_EN
EN/SET
FL_EN
EN_ LDOA
EN_ LDOA
BL7/FL2
FL1
EN_LDOB/C
EN_LDOB/C
VLDOA
at 300mA
CLDOA
LDOA
LDOB
VLDOB
at 300mA
CLDOB
2.2µF
2.2µF
VLDOC
at 300mA
CLDOC
2.2µF
LDOC
PGND
AGND
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2861.2009.02.1.2
1
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Pin Descriptions
Pin #
Symbol
Description
Charge pump output. OUT is the output of the charge pump and supplies current to the backlight and flash
LEDs. Connect the backlight and flash LED anodes to OUT. Bypass OUT to PGND with a 2.2ꢀF or larger
ceramic capacitor as close to the AAT2861 as possible.
1
OUT
2
3
C2+
Positive terminal of charge pump capacitor 2. Connect the 1ꢀF charge pump capacitor 2 from C2+ to C2-.
AS2Cwire serial input. EN/SET is the address and data input of the AS2Cwire serial interface. AS2Cwire is
EN/SET
used to control backlight, flash and LDO functions.
Flash enable. FL_EN is the enable control for the Flash LEDs. For the FL_EN pin to enable the flash current,
the EN/SET pin must also be pulled high.
LDO A enable pin. EN_LDOA turns on or off LDO regulator A. The EN/SET pin must also be pulled high for
LDO A to be enabled. The EN_LDOA input can be overwritten via the AS2Cwire interface to disable LDO A.
4
5
FL_EN
EN_LDOA
LDO B and LDO C enable pin. EN_LDOB/C enables both LDO regulators B and C. The EN/SET pin must
6
EN_LDOB/C also be pulled high for the LDO regulators to be enabled. The EN_LDOB/C input can be overwritten via the
AS2Cwire interface to disable either LDO B or LDO C.
7
8
AGND
LDOC
IN
Analog ground. Connect AGND to PGND at a single point as close to the AAT2861 as possible.
LDOC is the voltage output of LDO C. Bypass LDOC to AGND with a 2.2ꢀF or larger capacitor as close to
the AAT2861 as possible.
Input power pin for all three LDOs. Connect Pin 9 to Pin 23 with as short a PCB trace as practical.
9
LDOB is the voltage output of LDO B. Bypass LDOB to AGND with a 2.2ꢀF or greater capacitor as close to
the AAT2861 as possible.
10
LDOB
LDOA is the voltage output of LDO A. Bypass LDOA to AGND with a 2.2ꢀF or larger ceramic capacitor as
close to the AAT2861 as possible.
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.
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 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 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.
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.
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.
11
12
13
14
15
16
17
LDOA
BL1
BL2
BL3
BL4
BL5
BL6
AAT2861-1/3: Backlight LED 7 current sink. BL7 controls the current through backlight LED 7. Connect the
cathode of backlight LED 7 to BL7. If not used, connect BL7 to OUT.
AAT2861-2: 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.
18
BL7 (FL2)
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.
19
FL1
20
21
22
PGND
C2-
C1-
Power ground. Connect PGND to AGND at a single point as close to the AAT2861 as possible.
Negative terminal of charge pump capacitor 2.
Negative terminal of charge pump capacitor 1.
Power input. Connect IN to the input source voltage. Bypass IN to PGND with a 2.2ꢀF or larger ceramic
capacitor as close to the AAT2861 as possible.
23
IN
24
EP
C1+
Positive terminal of charge pump capacitor 1. Connect the 1ꢀF charge pump capacitor 1 from C1+ to C1-.
Exposed paddle (bottom) Connect to PGND/AGND.
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2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Pin Configuration
TQFN34-24
(Top View)
24
23
22
21
20
1
2
3
4
19
18
17
16
15
14
13
OUT
C2+
FL1
BL7 (FL2)
BL6
EN/SET
_
FL EN
BL5
_
5
6
7
EN LDOA
BL4
_
EN LDOB/C
BL3
AGND
BL2
8
9
10
11
12
Part Number Descriptions1
Backlight LED Outputs
Part Number
Main
Sub
Flash LED Outputs
AAT2861IMK-1-T1
AAT2861IMK-2-T1
AAT2861IMK-3-T1
4
4
5
3
2
2
1
2
1
Absolute Maximum Ratings2
Symbol Description
Value
Units
IN, OUT, BL1, BL2, BL3, BL4, BL5, BL6, BL7/FL2, FL1 Voltage to AGND
C1+, C2+ Voltage to AGND
C1-, C2-, LDOA, LDOB, LDOC, EN/SET, FL_EN, EN_LDOA, EN_LDOB/C Voltage to AGND
PGND Voltage to AGND
-0.3 to 6.0
-0.3 to VOUT + 0.3
-0.3 to VIN + 0.3
-0.3 to 0.3
V
V
V
V
TJ
TLEAD
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
-40 to 150
°C
°C
300
Thermal Information3,4
Symbol Description
Value
Units
PD
θJA
Maximum Power Dissipation
Maximum Thermal Resistance
2.0
50
W
°C/W
1. Backlight and Flash Configuration within a part number is configured though the AS2Cwire serial interface. For example, disabling the “Main Equals Sub” feature (Address 8,
Data 5 - 8) in the AAT2861-1 will configure BL1-BL4 LED outputs as MAIN and BL5-BL7 outputs as SUB.
2. 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.
3. Derate 20mW/°C above 25°C ambient temperature.
4. Mounted on a FR4 circuit board.
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2861.2009.02.1.2
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PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Electrical Characteristics1
VIN = 3.6V; CIN = COUT = 2.2ꢀF; C1 = C2 = 1μF; 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
IN Operating Current (1x mode, Main
Channels enabled, IBLX not included)
EN/SET = IN, BL1-BL7 = IN, FL_EN =
EN_LDOA = EN_LDOB/C = AGND
600
μA
IN Operating Current (2x mode, Main
Channels enabled, IBLX not included)
IN Operating Current (LDOA, LDOB and EN/SET = EN_LDOA = EN_LDOB/C = IN; FL_EN
LDOC enabled)
IN Operating Current (Only LDOA
enabled)
2X Mode; EN/SET = IN, FL_EN = EN_LDOA =
EN_LDOB/C = AGND; BL1-BL7 = OPEN
5.5
mA
μA
μA
IIN
225
= AGND; ADDR = 3; DATA = 1; No Load
EN/SET = EN_LDOA = IN; FL_EN = EN_LDOB/C
= AGND, ADDR = 3; DATA = 1; No Load
80
IIN(SHDN)
TSD
TSD(HYS)
IN Shutdown Current
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
EN/SET, FL_EN, EN_LDOA, EN_LDOB/C = AGND
1.0
μA
°C
°C
140
15
Charge Pump Section
VOUT
OUT Output Voltage
5.2
V
IOUT(MAX)
OUT Maximum Output Current
VIN = 3.0V, VOUT = 4.0
800
mA
BL1-BL7 Charge Pump Mode Transition
Hysteresis
FL1-FL2 Charge Pump Mode Transition
Hysteresis
EN/SET = IN; VIN – VF = 1V; ADDR = 0, DATA =
16; ADDR = 3, DATA = 3; ADDR = 2, DATA = 12
EN/SET = FL_EN = IN; VIN – VF = 1V; ADDR =
10, DATA = 1
VIN(TH_H, BL)
VIN(TH_H, FL)
0.3
1
V
V
fOSC
tCP(SS)
Charge Pump Oscillator Frequency
Charge Pump Soft-Start Time
TA = 25°C
TA = 25°C
1
100
MHz
μs
BL1-BL6, BL7/FL2, FL1 LED Drivers
EN/SET = IN; VIN – VF = 1V; ADDR = 0, DATA =
16; ADDR = 3, DATA = 3; ADDR = 2, DATA = 12
EN/SET = IN; VIN – VF = 1V; ADDR = 0, DATA =
16; ADDR = 3, DATA = 4; ADDR = 2, DATA = 14
EN/SET = IN; VIN – VF = 1V; ADDR = 0, DATA =
16; ADDR = 3, DATA = 3; ADDR = 2, DATA = 12
IBLx
BL1-BL7 Current Accuracy
BL1-BL7 Current Accuracy
BL1-BL7 Current Matching2
18
20
2
22
mA
mA
%
IBL_x
1.6
2.4
ΔI(BLx)
IBL(AVG)
/
3
BL1-BL7 Charge Pump Transition
Threshold
EN/SET = IN; VIN – VF = 1V; ADDR=0, DATA =
16; ADDR = 3, DATA = 3; ADDR = 2, DATA = 12
VBL_(TH)
0.2
V
EN/SET = IN; VIN – VF = 1V; ADDR = 0, DATA =
16; ADDR = 1, DATA = 1; ADDR = 2, DATA =
12; ADDR = 3, DATA = 3
EN/SET = FL_EN = IN; VIN – VF = 1V; ADDR =
10, DATA = 1
EN/SET = FL_EN = IN; VIN – VF = 1V; ADDR =
10, DATA = 13
EN/SET = FL_EN = IN; VIN – VF = 1V, ADDR =
10, DATA = 1
EN/SET = FL_EN = IN; VIN – VF = 1V; ADDR =
10, DATA = 1
EN/SET = FL_EN = IN; VIN – VF = 1V; ADDR =
11, DATA = 1
BL1-BL7 Automatic Fade-In/Fade-Out
Timer
tFADE
IFL[1]
0.75
1
1.25
s
FL1 Current Accuracy
540
108
600
120
5
660
132
mA
mA
%
V
IFL[1](DATA13) FL1 Current Accuracy
ΔI(FLx)
IFL(AVG)
/
FL1-FL2 Current Matching (AAT2861-2
only)
VFL[1/2](TH) FL1 Charge Pump Transition Threshold
0.45
2
ΔtFL/tFL_SET Flash Safety Timer Period
1.5
2.5
s
1. The AAT2861 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correla-
tion with statistical process controls.
2. Current matching is defined as the deviation of any sink current from the average of all active channels.
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2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Electrical Characteristics (continued)1
VIN = 3.6V; CIN = COUT = 2.2ꢀF; C1 = C2 = 1μF; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA =
25°C.
Symbol
Description
Conditions
Min Typ Max Units
Linear Regulators
ILDO = 1mA to 200mA; TA = 25°C -1.5
1.5
3.0
%
%
ΔVLDO[A/B/C]
VLDO[A/B/C]
/
LDOA, LDOB, LDOC Output Voltage Tolerance
ILDO = 1mA to 200mA;
-3.0
TA = -40°C to +85°C
ILDO[A/B/C](MAX) LDOA, LDOB, LDOC Load Current
VLDO[A/B/C](DO) LDOA, LDOB, LDOC Dropout Voltage2
200
mA
mV
VLDO[A/B/C] ≥ 3.0V; ILDO = 150mA
75
150
ΔVLDO
LDO*ΔVIN
/
LDOA, LDOB, LDOC Line Regulation
VIN = (VLDO[A/B/C] + 1V) to 5V
ILDO[A/B/C] = 10mA, 1kHz
0.09
%/V
V
PSRR[A/B/C]
ROUT_(DCHG)
EN/SET AS2Cwire and Logic Control
LDOA, LDOB, LDOC Power Supply Rejection Ratio
LDOA, LDOB, LDOC Auto-Discharge Resistance
50
20
dB
Ω
EN/SET, FL_EN, EN_LDOA, EN_LDOB/C Input High
Threshold Voltage
EN/SET, FL_EN, EN_LDOA, EN_LDOB/C Input Low
Threshold Voltage
EN/SET, FL_EN, EN_LDOA, EN_LDOB/C Input Leak-
age Current
VIH
VIL
2.7V ≤ VIN ≤ 5.5V
2.7V ≤ VIN ≤ 5.5V
EN/SET = IN = 5V
1.4
V
V
0.4
1
IIN(LKG)
-1
ꢀA
tEN/SET(OFF)
tEN/SET(LAT)
tEN/SET(LOW)
tENSET(H-MIN)
tENSET(H-MAX)
EN/SET Input OFF Timeout
EN/SET Input Latch Timeout
EN/SET Input LOW Time
EN/SET Minimum High Time
EN/SET Maximum High Time
500
500
75
μs
μs
μs
ns
μs
0.3
50
75
1. The AAT2861 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correla-
tion with statistical process controls.
2. VDO[A/B/C] is defined as VIN – LDO[A/B/C] when LDO[A/B/C] is 98% of nominal.
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PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Typical Characteristics
Backlight Efficiency vs. Input Voltage
Flash Efficiency vs. Input Voltage
100
90
100
90
80
70
60
50
40
30
80
70
60
50
30mA/ch, VF = 3.95V
320mA/ch, VF = 3.25V
160mA/ch, VF = 3.15V
15mA/ch, VF = 3.5V
4.2mA/ch, VF = 3.4V
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)
Backlight Current Matching vs. Temperature
Charge Pump Output Turn On Characteristic
(VIN = 3.6V; 20mA/ch)
(VIN = 3.6V; 0mA/ch; COUT = 2.2µF)
22
21
20
19
4.0
2.0
0.0
4.0
3.0
2.0
1.0
0.0
Channel 1 - Channel 6/7
18
17
16
-40
-15
10
35
60
85
Temperature (°C)
Time (50µs/div)
Turn On to 1X Mode Flash
Turn On to 1.5X Mode Flash
(VIN = 4.2V; 300mA/ch)
(VIN = 3.6V; 300mA/ch)
4
2
0
4
2
VFL_EN
(2V/div)
VFL_EN
(2V/div)
0
VOUT
(2V/div)
VFLX
VOUT
4
2
0
4
2
0
(2V/div)
VFLX
(2V/div)
(2V/div)
600
400
200
0
600
400
200
0
IIN
IIN
(200mA/div)
(200mA/div)
Time (50µs/div)
Time (50µs/div)
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2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Typical Characteristics
Turn On to 2X Mode Flash
Turn On to 1X Mode Backlight
(VIN = 2.8V; 300mA/ch)
(VIN = 3.6V; 20mA/ch)
4
2
VEN/SET
VFL_EN
(2V/div)
(2V/div)
0V
0
VOUT
(2V/div)
VSINK
(2V/div)
4
2
0
VOUT
(2V/div)
VFLX
0V
0A
600
400
200
0
(2V/div)
IIN
IIN
(200mA/div)
(100mA/div)
Time (50µs/div)
Time (200µs/div)
Turn On to 1.5X Mode Backlight
Turn On to 2X Mode Backlight
(VIN = 3.2V; 20mA/ch)
(VIN = 3.0V; 20mA/ch)
VEN/SET
(2V/div)
VEN/SET
(2V/div)
0V
0V
VOUT
VOUT
(2V/div)
VSINK
(2V/div)
VSINK
(2V/div)
0V
0A
0V
0A
(2V/div)
IIN
IIN
(200mA/div)
(200mA/div)
Time (200µs/div)
Time (200µs/div)
Turn Off from 1.5X Mode Backlight
Operating Characteristic
(VIN = 3.2V; 20mA/ch)
(VIN = 3.2V; 20mA/ch Backlight; 1.5x Mode; COUT = 2.2µF)
20
10
0
VEN/SET
(2V/div)
VDIODE
(2V/div)
50
0
IIN
-50
(200mA/div)
Time (500ns/div)
Time (200µs/div)
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PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Typical Characteristics
Operating Characteristic
LDO A/B/C Load Regulation
(VIN = 3.0V; 20mA/ch Backlight; 2X Mode; COUT = 2.2µF)
(VIN = 3.6V)
1.5
1.0
VOUT = 1.8V
VOUT = 3.0V
20
10
0
0.5
20
10
0
0.0
-0.5
-1.0
-1.5
-10
-20
0.1
1
10
100
1000
Time (500ns/div)
Load Current (mA)
LDO A/B/C Output Voltage vs. Temperature
LDO A/B/C Load Transient Response
(VIN = 3.6V; ILDO = 0mA)
(
ILDO
=
10mA to 200mA; VIN = 3.6V; VLDO = 1.8V; CLDO = 2.2µF)
1.5
VOUT = 1.8V
200
100
0
V
OUT = 3.3V
1.0
0.5
-100
-200
-300
-400
-500
2.00
1.90
1.80
1.70
1.60
0.0
-0.5
-1.0
-1.5
-40
-15
10
35
60
85
Temperature (°C)
Time (20µs/div)
LDO A/B/C Line Transient Response
LDO A/B/C Turn On Characteristic
(VIN = 3.6V to 4.2V; ILDO = 10mA; VOUT = 1.8V; CLDO = 2.2µF)
(VLDO = 1.8V; VIN = 3.6V; CLDO = 2.2µF)
4.4
4.0
4.0
2.0
0.0
3.6
1.82
1.81
1.80
1.79
1.78
1.5
1.0
0.5
0.0
Time (1ms/div)
Time (20µs/div)
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2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Typical Characteristics
EN/SET, FL_EN, EN_LDOA, EN_LDOB/C
High Threshold Voltage vs. Input Voltage
EN/SET, FL_EN, EN_LDOA, EN_LDOB/C
Low Threshold Voltage vs. Input Voltage
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
-40°C
-40°C
0.4
0.6
25°C
25°C
0.3
0.5
85°C
85°C
0.2
0.4
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5
Input Voltage (V)
Input Voltage (V)
EN/SET Input Latch Timeout vs. Input Voltage
EN/SET Input Off Timeout vs. Input Voltage
400
350
300
250
500
450
400
350
300
250
200
-40°C
200
-40°C
150
25°C
85°C
25°C
150
85°C
100
2.7
100
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Input Voltage (V)
w w w . a n a l o g i c t e c h . c o m
2861.2009.02.1.2
9
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Functional Block Diagrams
AAT2861IMK-1-T1
IN
IN
C1-
LDOA
LDOB
1x/1.5x/2x
C1+
Tri-mode
Charge Pump
C2-
C2+
OUT
LDOC
8
REF
BL1
BL2
BL3
BL4
EN/SET
FL_EN
Main
5
Backlight
Current
Control
Control
Logic
EN_LDOA
BL5
Sub
EN_LDOB/C
5
4
Backlight
Current
Control
BL6
BL7
Flash
Control
FL1
AGND
PGND
w w w . a n a l o g i c t e c h . c o m
10
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
AAT2861IMK-2-T1
IN
IN
C1-
LDOA
LDOB
C1+
1x/1.5x/2x
Tri-mode
Charge Pump
C2-
C2+
OUT
LDOC
8
REF
BL1
BL2
BL3
BL4
Main
EN/SET
FL_EN
5
Backlight
Current
Control
EN_LDOA
Control
Logic
Sub
BL5
BL6
5
4
Backlight
Current
Control
EN_LDOB/C
FL2
FL1
Flash
Control
PGND
AGND
w w w . a n a l o g i c t e c h . c o m
2861.2009.02.1.2
11
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
AAT2861IMK-3-T1
IN
IN
C1-
LDOA
LDOB
C1+
1x/1.5x/2x
Tri-mode
Charge Pump
C2-
C2+
OUT
LDOC
8
REF
BL1
BL2
BL3
BL4
BL5
EN/SET
FL_EN
5
Main
Backlight
Current
Control
EN_LDOA
Control
Logic
5
4
EN_LDOB/C
Sub
BL6
BL7
Backlight
Current
Control
Flash
Control
FL1
PGND
AGND
w w w . a n a l o g i c t e c h . c o m
12
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
imately 1mA steps while the flash LED current can be set
Functional Description
between 0 and 600mA in 40mA steps or 0 to 300mA in
20mA steps for two channel flash version. The backlight
LED currents match to within 3% while the flash LED
currents match to within 5%.
The AAT2861 is a highly integrated backlight and photo-
flash driver family with three LDO regulators. The charge
pump LED driver powers the backlight and flash LEDs
from the 2.7V to 5.5V input voltage. The LDO regulators
are powered from the same input and produce regulated
output voltage between 1.2V and 3.3V. Control of the
LEDs and the LDO output voltage is through an AS2Cwire
serial interface for easy programming.
To eliminate the latency of the AS2Cwire serial interface,
the flash LED is enabled through a dedicated input,
FL_EN. The AAT2861 also includes a safety timer that
prevents thermal overstress of the flash LED(s). This is
important because many flash LEDs operate for a brief
period beyond their steady-state operating limitations.
If the flash driving hardware and/or software fail to turn
the LED off, the safety timer insures that the LED or
other circuitry is not damaged.
LED Drivers
The AAT2861 drives six or seven backlight LEDs up to
31mA each and a total of 600mA flash current through
one or two channels. The LEDs are driven from a charge
pump to insure that constant current is maintained over
the entire battery voltage range. The charge pump auto-
matically switches from 1X, to 1.5X, to 2X modes and
back to maintain the LED current while minimizing
power loss for high efficiency. The charge pump operates
at the high 1MHz switching frequency, allowing the use
of small 1ꢀF ceramic capacitors.
Both the backlight and flash LED currents are pro-
grammed through the AS2Cwire serial interface as are
the backlight fade-in/fade-out timer and the flash safety
timer. See the “AS2Cwire Serial Interface Programming”
section of this datasheet for more information on setting
the LED currents.
LDO Regulators
Each individual LED is driven by a current sink to GND,
allowing individual current control with high accuracy
over a wide range of input voltages and LED forward
voltages while maintaining high efficiency.
The AAT2861 includes three low dropout (LDO) linear
regulators. These regulators are powered from the bat-
tery and produce a fixed output voltage set through the
AS2Cwire serial interface. The output voltage can be set
to one of 16 output voltages between 1.2V and 3.3V. The
LDO regulators can be turned on/off with the external
enable pins EN_LDOA and EN_LDOB/C. Additionally, the
AS2Cwire interface allows the LDO regulators to be
enabled independently when the EN_LDOA and EN_
LDOB/C pins are pulled high.
The charge pump is controlled by the voltage across the
LED current sinks. When any one of the active backlight
current sink/channel voltages drops below 200mV or the
flash current sink/channel drops below 450mV, the
charge pump goes to the next higher mode (from 1X to
1.5X or from 1.5X to 2X mode) to maintain sufficient
LED voltage for constant LED current. The AAT2861 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
300mV mode-transition hysteresis that prevents the
charge pump from oscillating between modes.
The LDO regulators require only a small 2.2ꢀF ceramic
output capacitor for stability. If improved load transient
response is required, larger-valued capacitors can be
used without stability degradation.
AS2Cwire Serial Interface Protocol
LED Current Control
The AAT2861 is dynamically programmable by the
AS2Cwire single-wire interface. AS2Cwire records rising
edges detected at the EN/SET pin to address and load
the data registers. The timing diagram in Figure 1 shows
the typical transmission protocol.
Both the backlight and flash LED currents are controlled
through the AS2Cwire serial interface. The backlight LED
current can be set between 0.5mA and 31mA in approx-
w w w . a n a l o g i c t e c h . c o m
2861.2009.02.1.2
13
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Address
Data
THI
TLAT
TLO
TLAT
EN/SET
Address
1
2
17
18
1
2 . . .
n <= 16
0
1
0
0
n
Data Reg 1
Data Reg 2
Figure 1: AS2Cwire Serial Interface Timing Diagram.
AS2Cwire latches data or address after the EN/SET input
has been held high for time tLAT (500μs). Address or data
is differentiated by the number of EN/SET rising edges.
Since the data registers are 4 bits each, the differentiating
number of pulses is 24 or 16, so that Address 0 is identi-
fied by 17 rising edges, Address 1 by 18 rising edges,
Address 2 by 19 rising edges, etc. Data is set to any num-
ber of rising edges between 1 and 16. A typical write
protocol is a burst of EN/SET rising edges identifying a
particular address, followed by a pause with EN/SET 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 pro-
grammed and LED Backlight channels BL1-BL7 will be
enabled according to the number of data edges applied.
Backlight Current Control (Address 0)
Address 0 controls the enabling of the Main and Sub
channels. Table 2 shows the Data Codes used to control
the Main and Sub Channels independently. The default
condition for all backlight outputs (BL1-BL7) is OFF after
power-up.
The AAT2861 family of LMUs also provides an internal LED
current fade-in, fade-out feature. This feature is useful in
those applications where it is preferred to turn on and off
the backlight current using a smooth transition versus an
abrupt transition. During the fade-in cycle, the LED cur-
rent will be slowly increased to the programmed current
level (set in Addresses 2 to 5). During the fade-out cycle,
the LED current will be decreased linearly down to its
programmed fade-out current threshold (set by Address
1) at which point the BL channels will be turned off. The
fade-in and fade-out current is a linear transition over a
time period of approximately 1 second.
The fade-in and fade-out function can be enabled and
disabled independently for the Main and Sub groups by
writing the desired Data to Address 0. Table 2 also lists
the data codes used to program enable and disable the
fade functions for the main and sub channels. If the
“Main Equals Sub” feature (Address 3) is enabled
(MEQS=1), the fade-in and fade-out settings for the Main
and Sub channels are controlled by the “Main Fade” set-
ting and the “Sub Fade” bit in Address 1 will be ignored.
When EN/SET is held low for a time longer than tOFF
(500μs), the AAT2861 enters shutdown mode and draws
less than 1μA of current from IN. At shutdown, the data
and address registers are reset to 0.
AS2Cwire Serial Interface Programming
The AAT2861’s AS2Cwire programmable Address regis-
ters are listed in Table 1. There are 14 Address registers,
four registers control the three LDOs, six control the
backlight LED configuration, two control the flash/lamp
LED configuration and two are used to individually dis-
able each backlight or flash channel.
At startup when the EN/SET pin is first pulled high,
Address 0 is the default active register. The main and
sub channels can be turned on by immediately writing
data. For example, if Data = 4 is written the main and
sub channels will turn on to the default value of 19mA.
w w w . a n a l o g i c t e c h . c o m
14
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
EN/SET
Address Rising Edges
Function
D3
D2
D1
D0
0
1
2
3
4
5
6
7
8
17
18
19
20
21
22
23
24
25
26
27
28
29
Backlight Main/Sub ON/OFF and Fade Enable FADE_SUB
FADE_MAIN
X
BLM[2]
X
BLS[2]
X
OFF_LDOC
LDOA[2]
LDOB[2]
LDOC[2]
F_HI[2]
X
SUB_ON
FLOOR[1]
BLM[1]
MEQS
BLS[1]
X
MAIN_ON
FLOOR[0]
BLM[0]
BLM[4]
BLS[0]
Backlight Fade Control
Backlight Current Main, LSB's
Backlight Current Main, MSB
Backlight Current Sub, LSB's
Backlight Current Sub, MSB
LDO Disable Control
X
BLM[3]
Reserved
BLS[3]
X
BLS[4]
X
OFF_LDOB OFF_LDOA
LDO A Output Voltage Control
LDO B Output Voltage Control
LDO C Output Voltage Control
Flash Current
LDOA[3]
LDOB[3]
LDOC[3]
F_HI[3]
X
LDOA[1]
LDOB[1]
LDOC[1]
F_HI[1]
F_TIME[1]
OFF_ BL2
LDOA[0]
LDOB[0]
LDOC[0]
F_HI[0]
F_TIME[0]
OFF_ BL1
9
10
11
12
Flash Timer Control
LED Channel Disable Control (BL1 – BL4)
OFF_BL4
OFF_ BL3
LED Channel Disable Control (BL5, BL6,
BL7/FL2, FL1)
13
30
OFF_FL1
OFF_BL7/FL2
OFF_BL6
OFF_BL5
Table 1: AAT2861- 1 Configuration/Control Register Allocation
(* signifies that the data bit has a POR default bit value = 1; X signifies “Don’t care”).
current threshold (set by Address 1) at which point the
BL channels will be turned off. The default fade-out cur-
rent level is 500μA, but can be changed to 1mA, 2mA or
3mA using the data codes listed in Table 3.
Sub
Main
Sub
Main
Data
Fade On Fade On Channel Channel
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
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
Data
Fade Out Current Level (mA)
No
1*
2
0.50*
1.0
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Yes
Yes
3
2.0
4
3.0
Table 3: Backlight Fade-In and Fade-Out Control
(Address 1).
Backlight Current Control (Addresses 2 to 5)
The AAT2861’s AS2Cwire Addresses 2, 3, 4, and 5 control
the backlight LED output current level in Main and Sub
group of outputs. Address 2 and Address 3 control the
Main backlight channel current to one of 32 levels
according to Table 4 below. Address 3 acts as the MSB
and Address 2 acts as the LSB for the current level
setup. Address 4 and Address 5 control the Sub back-
light channels current to one of 32 levels according to
Table 5 below.
Table 2: Backlight Main/Sub ON/OFF and Fade
Enable (Address 0).
Backlight Fade-In and Fade-Out Control
(Address 1)
During the fade-out cycle, the LED current will be
decreased linearly down to its programmed fade-out
*Denotes the default (power-on-reset) value
w w w . a n a l o g i c t e c h . c o m
2861.2009.02.1.2
15
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Main Equals Sub OFF (MEQS=0)
Main Equals Sub ON (MEQS=1)
Address
Data
Address
Data
Main Current
Address
Data
Address
Data
Main Current
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
1
1
1
1
1
1
1
1
1
1
1
1*
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
2
3
4
5
6
7
8
9
10
11
12*
13
14
15
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
31
30
29
28
27
26
25
24
23
22
21
20*
19
18
17
16
15
14
13
12
11
10
9
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
8
7
6
5
4
3
2
1
0.5
0.5
Table 4: Backlight Main Current Control (Addresses 2 and 3).
w w w . a n a l o g i c t e c h . c o m
16
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
For example, a change from 28mA to 8mA in the Main
backlight channels should follow this procedure. First,
Sub Backlight
Address
Data
Address
Data
Sub Current
28mA is set by programming Data = 3 to Address 2 and
Data=1 to Address 3. When changing to 8mA first write
Data=2 to Address 3. The current level will not change
after this step. Then write Data=7 to Address 2. After
Address 2 has been latched the new 8mA current level
will be set.
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
1
1
1
1
1
1
1
1
1
1
1
1*
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
1
2
3
4
5
6
7
8
9
10
11
12*
13
14
15
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
31
30
29
28
27
26
25
24
23
22
21
20*
19
18
17
16
15
14
13
12
11
10
9
Address 3 also controls the “Main Equals Sub” feature in
the AAT2861 products. This feature allows all backlight
channels to be controlled with only the Main Channel
current settings. If the “Main Equals Sub” feature is
turned on (Data 3, or 4 in Address 3) the current set-
tings of the Sub Channel are ignored. All backlight chan-
nels will be set to the same current levels as determined
by the Data programmed to “Backlight Current Main” in
Addresses 2 and 3. The Main and Sub channels are
turned on and off by the “Main On” setting in Address 0.
The default condition is for the “Main Equals Sub” feature
to be turned OFF (MEQS=0) after power-up.
Table 6 shows the Main and Sub Channel Configurations
for the three versions of the AAT2861. The effect of the
“Main Equals Sub” feature is clearly represented in this
table.
8
7
6
5
4
3
2
1
Main Equals Sub (IMAIN = ISUB
)
Part Number
Yes (Default)
No
AAT2861-1
AAT2861-2
AAT2861-3
7M+0S+1FL
6M+0S+2FL
7M+0S+1FL
4M+3S+1FL
4M+2S+2FL
5M+2S+1FL
0.5
Table 6: Main and Sub Channel Configurations.
Table 5: Backlight Sub Current Control
(Addresses 4 and 5).
LDO Output Voltage Control
(Addresses 6 to 9)
The current settings for the Main and Sub channels are
each divided into two Addresses. Any change in Data to
the “Backlight Current Main (or Sub), LSB’s” Address will
result in an immediate change to the LED current output
level. Programming new current settings that require a
change to both “Backlight Current Main (or Sub), MSB”
and “Backlight Current Main (or Sub), LSB’s” Addresses
could result in an errant intermediate current setting. To
avoid this problem when the Data in “Backlight Current
Main (or Sub), MSB” Address is changed the new current
setting will not take effect until “Backlight Current Main
(or Sub), LSB’s” Address has been written to and
latched.
The AAT2861’s three LDO regulators are configured by
programming Addresses 6, 7, 8, and 9 via the AS2Cwire
interface. With the EN/SET pin pulled high and the
AAT2861 turned on, LDOA can be enabled using the EN_
LDOA pin. LDOB and LDOC can be enabled together using
the EN_LDOB/C pin. Additional LDO regulator control can
be achieved using Address 6 to override the enable com-
mand of the EN_LDOA and EN_LDOB/C pins. For example,
with the EN_LDOA and EN_LDOB/C pins enabled, writing
Data 5 to Address 6 will disable LDOB and leave LDOA and
LDOC enabled. Table 7 shows the LDO disable control.
Writing data to Addresses 7, 8, and 9 set the output volt-
ages for LDOA, LDOB, and LDOC to one of 16 levels. The
available LDO output voltages are shown in Table 8.
w w w . a n a l o g i c t e c h . c o m
2861.2009.02.1.2
17
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Flash Driver Control (Address 10 and 11)
Data
LDO C
LDO B
LDO A
The AAT2861-1 and AAT2861-3 are both configured with
a single 600mA LED Flash channel, while the AAT2861-2
is configured with two LED Flash channels each capable
of driving 300mA per channel. Address 10 programs the
flash current level. Table 9 lists the data codes for the
programming Address 10. Upon startup, the power-on-
reset value in Address 10 is set to data code 13.
Controlled by Controlled by Controlled by
1*
2
EN_LDOB/C* EN_LDOB/C*
EN_LDOA*
Controlled by Controlled by
OFF
EN_LDOB/C
EN_LDOB/C
OFF
Controlled by
EN_LDOB/C
Controlled by
EN_LDOA
3
Controlled by
EN_LDOB/C
4
OFF
OFF
Controlled by Controlled by
5
OFF
OFF
EN_LDOB/C
EN_LDOA
Flash Current (mA) per Output
Controlled by
EN_LDOB/C
6
OFF
Data
AAT2861-1 or -3
AAT2861-2
1
2
3
4
5
6
7
8
9
10
11
12
13*
14
15
16
600
560
520
480
440
400
360
320
280
240
200
160
120*
80
300
280
260
240
220
200
180
160
140
120
100
80
Controlled by
EN_LDOA
7
8
OFF
OFF
OFF
OFF
OFF
Table 7: LDO Disable Control (Address 6).
Data
VLDOA (V)
VLDOB (V)
VLDOC (V)
1
2
3
4
5*
6
7
8
9
10
11
12
13
14
15
16
1.2
1.3
1.5
1.6
1.8*
2
2.2
2.5
2.6
2.7
2.8
2.9
3
1.2
1.3
1.5
1.6
1.8*
2
2.2
2.5
2.6
2.7
2.8
2.9
3
1.2
1.3
1.5
1.6
1.8*
2
2.2
2.5
2.6
2.7
2.8
2.9
3
60*
40
20
40
OFF
OFF
Table 9: Flash Current Level (Address 10).
Once the EN/SET pin is pulled high and the AAT2861 has
turned on, the LED Flash channels can be enabled by
pulling the FL_EN to IN. The current setting of the LED
Flash channels can be changed prior to enabling the
flash current, or while the flash current is on.
3.1
3.2
3.3
3.1
3.2
3.3
3.1
3.2
3.3
Table 8: LDO X Output Voltage
(Addresses 7, 8, and 9).
The LED Flash controller also comes with a safety timer
to prevent excessive heat generation and power loss
from extended high current power dissipation. The LED
flash safety timer duration can be set to four values by
writing to Address 11. The default value at startup is 2
seconds. Table 10 shows the Data Codes for the flash
safety timer.
Fast turn-off response time is achieved by an active out-
put pull-down circuit, which is enabled when the LDO
regulator is disabled.
*Denotes default (power-on-reset) value.
w w w . a n a l o g i c t e c h . c o m
18
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Torch/movie mode is automatically entered when the
flash current setting is programmed to 120mA (60mA for
channel for the AAT2861-2) or lower with Data = 13, 14,
or 15. At these current levels the safety timer is auto-
matically disabled and the flash channels will remain on
as long as the FL_EN pin remains active. Extended dura-
tion flash use can be achieved for higher current settings
by writing Data 4 to Address 11 to disable the safety
timer. Though the AAT2861 includes an internal thermal
limit circuit, be careful to limit the current setting (Address
10) to a value that will not generate excessive heat which
may damage the flash LEDs or external circuitry.
LED Channel Disable Control
(Address 12 and 13)
Addresses 12 and 13 allow for additional programming
flexibility by allowing each LED channel to be indepen-
dently disabled. Normally, the backlight channels are
controlled by MAIN_ON and SUB_ON controls in Address
0, while the FL_EN pin turns on the flash channels.
Writing to Addresses 12 and 13 can override these con-
trols to allow for any combination of LEDs to be turned
on. The default state is for all LED channels to be
“Conditionally ON” to allow the normal enable control.
In the following example we see how to turn on BL1,
BL2, BL6, and BL7 in the AAT2861-1 (4M+3S+1FL). First
write Address 12, Data=13 and Address 13, Data=10 to
disable BL3, BL4, BL5, FL1. Then program the desired
current setting using Addresses 2 through 5. Finally,
write Address 0, Data=4.
Data
Flash Time (sec)
1*
2
2*
1
3
0.5
4
Always ON
(NOTE: ”Conditionally ON” state allows the LED channel
to be turned ON but does not turn the channel ON. For
BL1 to be enabled Data=2, 4, 6, 8… must be written to
Address 0, and Data=1, 3, 5, 7… must be written to
Address 12.)
Table 10: Flash Safety Timer (Address 11).
Data
BL4
BL3
BL2
BL1
1*
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Conditionally ON*
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
OFF
Conditionally ON*
Conditionally ON
Conditionally ON
Conditionally ON
OFF
Conditionally ON*
Conditionally ON
OFF
Conditionally ON*
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
OFF
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
OFF
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
OFF
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
OFF
Table 11: LED Channel Individual Disable Control, BL1-BL4 (Address 12).
*Denotes default (power-on-reset) value.
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2861.2009.02.1.2
19
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Data
FL1
BL7/FL2
BL6
BL5
1*
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Conditionally ON*
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
OFF
Conditionally ON *
Conditionally ON
Conditionally ON
Conditionally ON
OFF
Conditionally ON*
Conditionally ON
OFF
Conditionally ON*
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
OFF
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
OFF
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
OFF
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
OFF
Table 12: LED Channel Individual Disable Control, BL5, BL6, BL7/FL2, FL1 (Address 13).
Device Switching Noise Performance
Applications Information
The AAT2861 operates at a fixed frequency of approxi-
LED Selection
mately 1MHz to control noise and limit harmonics that
can interfere with the RF operation of cellular telephone
handsets or other communication devices. Back-injected
noise appearing on the input pin of the charge pump is
20mV peak-to-peak, typically ten times less than induc-
tor-based DC/DC boost converter white LED backlight
solutions. The AAT2861 soft-start feature prevents noise
transient effects associated with in-rush currents during
the start up of the charge pump circuit.
The AAT2861 is specifically intended for driving white
LEDs. However, the device design will allow the AAT2861
to drive most types of LEDs with forward voltage speci-
fications ranging from 2.0V to 4.7V. LED applications
may include mixed arrangements for display backlight-
ing, color (RGB) LEDs, infrared (IR) diodes and any
other load needing a constant current source generated
from a varying input voltage. Since the BL1 to BL6, BL7/
FL2 and FL1 constant current sinks are matched with
negligible voltage dependence, the constant current
channels will be matched regardless of the specific LED
forward voltage (VF) levels.
Device Power Efficiency
Charge-pump efficiency discussion in the following sec-
tions accounts only for the efficiency of the charge pump
section itself. Due to the unique circuit architecture and
design of the AAT2861, it is very difficult to measure
efficiency in terms of a percent value comparing input
power over output power.
The low-dropout current sinks in the AAT2861 maximize
performance and make it capable of driving LEDs with
high forward voltages. Multiple channels can be com-
bined to obtain a higher LED drive current without com-
plication.
*Denotes default (power-on-reset) value.
w w w . a n a l o g i c t e c h . c o m
20
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Since the AAT2861 outputs are pure constant current
sinks and typically drive individual loads, it is difficult to
measure the output voltage for a given output (BL1 to
BL6, BL7/FL2, and FL1) to derive an overall output power
measurement. For any given application, white LED for-
ward voltage levels can differ, yet the output drive cur-
rent will be maintained as a constant.
The AAT2861 charge pump is a fractional charge pump
which will boost the input supply voltage in the event
where IN is less then the required output voltage across
the backlight white LED load. The efficiency can be sim-
ply defined as a linear voltage regulator with an effective
white LED forward voltage that is equal to one and a half
(1.5x mode) times the input voltage.
This makes quantifying output power a difficult task
when taken in the context of comparing to other white
LED driver circuit topologies. A better way to quantify
total device efficiency is to observe the total input power
to the device for a given LED current drive level. The
best white LED driver for a given application should be
based on trade-offs of size, external component count,
reliability, operating range and total energy usage...not
just "% efficiency."
With an ideal 1.5x charge pump, the input current is
1.5x of the output current. The expression to define the
estimated ideal efficiency (η) for the AAT2861 in 1.5x
mode is as follows:
PLEDs VLED1 · ILED1 + ... + VLEDX · ILEDX
η =
=
PIN
VIN · IIN
X · VLEDX · I
VIN · IIN
η =
η =
LEDX ; X = 1, 2, 3, ..., 6 or 7 and IIN = 1.5(X · ILEDX
)
The AAT2861 efficiency may be quantified under very
specific conditions and is dependant upon the input volt-
age versus the output voltage seen across the loads
applied to outputs BL1 through BL6, BL7/FL2 or FL1 for
a given constant current setting. Depending on the com-
bination of IN and voltages sensed at the current sinks,
the device will operate in "Load Switch" (1X) mode.
When any one of the voltages sensed at the current
sinks nears dropout the device will operate in 1.5X or 2X
charge pump mode. Each of these modes will yield dif-
ferent efficiency values. One should refer to the following
two sections for explanations for each operational
mode.
VLEDX
1.5VIN
The same calculations apply for the AAT2861 in 2x mode
where for an ideal 2x charge pump, the input current is
2x of the output current. The expression for the esti-
mated ideal efficiency (η) for the AAT2861 in 2x mode is
as follows:
PLEDs VLED1 · ILED1 + ... + VLEDX · ILEDX
η =
=
PIN
VIN · IIN
X · VLEDX · I
VIN · IIN
η =
η =
LEDX ; X = 1, 2, 3, ..., 6 or 7 and IIN = 2(X · ILEDX
)
AAT2861 charge pump conversion efficiency is defined
as the power delivered to the white LED load divided by
the input power:
VLEDX
2VIN
In addition, with an ideal 1.5x charge pump, the output
current may be expressed as 2/3 of the input current.
For a charge pump with an output of 5V and a nominal
input of 3.5V, the theoretical efficiency is 95%. Due to
internal switching losses and IC quiescent current con-
sumption, the actual efficiency can be measured at 93%.
Efficiency will decrease substantially as load current
drops below 1mA or when the level of IN approaches
OUT. The same calculations apply for 2X mode where the
output current then becomes 1/2 of the input current.
PLEDs VLED1 · ILED1 + ... + VLEDX · ILEDX
η =
=
PIN
VIN · IIN
VLEDX = White LED Forward Voltage (VF)
ILEDX = White LED Bias Current (ID)
X = Number of White LEDs
The expression to define the estimated ideal efficiency
(η) for the AAT2861 in 1X mode is as follows:
PLEDs X · VLEDX · ILEDX
η =
=
PIN
VIN · IIN
Capacitor Selection
X = 1, 2, 3, ..., 6 or 7 and IIN = X · ILEDX
Careful selection of all external capacitors CIN, C1, C2,
C
LDO(A/B/C), and COUT is important because they will affect
VLEDX
VIN
turn-on time, output ripple and transient performance.
Optimum performance will be obtained when low ESR
η =
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2861.2009.02.1.2
21
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
ceramic capacitors are used. In general, low ESR may be
defined as less than 100mΩ.
These larger size capacitors can improve circuit transient
response when compared to an equal value capacitor in
a smaller package size.
Ceramic composition capacitors are highly recommended
over all other types of capacitors for use with the
AAT2861. Ceramic capacitors offer many advantages
over their tantalum and aluminum electrolytic counter-
parts. A ceramic capacitor typically has very low ESR, is
lowest cost, has a smaller printed circuit board (PCB)
footprint, and is non-polarized. Since ceramic capacitors
are non-polarized, they are not prone to incorrect con-
nection damage.
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.
Figures 2 and 3 illustrate an example PCB layout. The
bottom of the package features an exposed metal pad-
dle. The exposed paddle acts, thermally, to transfer heat
from the chip and, electrically, as a ground connection.
Equivalent Series Resistance (ESR)
ESR is an important characteristic to consider when
selecting a capacitor. ESR is a resistance internal to a
capacitor, which is caused by the leads, internal connec-
tions, size or area, material composition and ambient
temperature. Capacitor ESR is typically measured in mil-
liohms for ceramic capacitors and can range to more
than several ohms for tantalum or aluminum electrolytic
capacitors.
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.
Ceramic Capacitor Materials
Ceramic capacitors less than 0.1μF are typically made
from NPO or COG materials. NPO and C0G materials
typically have tight tolerance and are stable over tem-
perature. Larger capacitor values are typically composed
of X7R, X5R, Z5U or Y5V dielectric materials. Large
ceramic capacitors, typically greater than 2.2μF are
often available in low cost Y5V and Z5U dielectrics, but
capacitors greater than 1μF are typically not required for
AAT2861 applications.
The chip ground is internally connected to both the
paddle and to the AGND and PGND pins. It is good prac-
tice 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 connected
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 large will have a lower ESR when
compared to an equivalent material smaller capacitor.
Manufacturer
Part Number
Value
Voltage
Temp. Co.
Case
0603ZD105K
0603ZD225K
1ꢀF
2.2ꢀF
1ꢀF
2.2ꢀF
4.7ꢀF
1ꢀF
10
10
25
16
10
16
10
10
AVX
X5R
0603
C1608X5R1E105K
C1608X5R1C225K
C1608X5R1A475K
GRM188R61C105K
GRM188R61A225K
LMK107BJ475KA
TDK
X5R
0603
Murata
X5R
X5R
0603
0603
2.2ꢀF
4.7ꢀF
Taiyo Yuden
Table 13: Surface Mount Capacitors.
w w w . a n a l o g i c t e c h . c o m
22
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
The evaluation board is made flexible so that the user
Evaluation Board User Interface
can disconnect the enable line from the microcontroller
and apply external enable signal. External enable signal
must be applied to the EN/SET pin.
The user interface for the AAT2861 evaluation board is
provided by four buttons and a number of connection
terminals. The board is operated by supplying external
power and pressing individual buttons or button combi-
nations. Table 14 indicates the function of each button or
button combination.
When applying external enable signal, consideration
must be given to the voltage levels. The externally
applied voltage should not exceed the supply voltage
that is applied to the IN pins of the device (DC+).
To power-on the evaluation board, connect a power sup-
ply or battery to the DC- and DC+ terminals. A red LED
indicates that power is applied.
The LDO loads can be connected directly to the evalua-
tion board. For adequate performance, be sure to con-
nect the load between LDOA/LDOB/LDOC and DC- as
opposed to some other GND in the system.
Button(s) Pushed Description
[Push/Release once] LDOA, LDOB and LDOC outputs are programmed to 1.2V. With every subsequent
push/release LDOA, LDOB and LDOC output voltages are incremented according to Table 8.
[Push/hold more than 2 sec] LDOA, LDOB and LDOC outputs will start to cycle through all programmable
voltage settings according to Table 8.
SW1
[Push/Release once] All channels are turned on as Main backlight with 31mA per channel. With every
subsequent push/release the backlight current is decreased according to Table 4.
[Push/hold more than 2 sec] All channels Main and Sub are turned on with 31mA per channel and fade
out sequence is initiated. The cycle proceeds with fade in for Main channels only, followed by fade in se-
quence for Sub channels. When these sequences are finished the program will restart fade out sequence
for all Main and Sub channels.
SW2
[Push/Release once] Flash channels are programmed with maximum current and timer. With every sub-
sequent push/release the flash current is decreased according to Table 9. The FLASH button needs to be
pressed down simultaneously.
SW3
FLASH
This button is connected directly to FL_EN pin. Press and hold for the flash to be enabled.
Table 14: AAT2861 Evaluation Board User Interface.
w w w . a n a l o g i c t e c h . c o m
2861.2009.02.1.2
23
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
OUT
C4
4.7µF
DC+
IN
C1
1.0µF
R5
0
DF1
D7
DF2
C2
1.0µF
U1
24
23
22
21
20
AAT2861-X
D2 D1
D3
D5 D4
D6
C1+ IN C1- C2- PGND
1
2
3
4
5
6
7
19
18
17
16
15
14
13
OUT
FL1
C8
C2+
BL7/FL2
BL6
2.2µF
EN/SET
FL_EN
EN_LDOA
EN_LDOB/C
AGND
BL5
BL4
FLASH
BL3
5
4 1
3 2
BL2
R4
10K
DC+
LDOC IN
LDOB LDOA BL1
8
9
10
11
12
C3
2.2µF
C6
2.2µF
C5
4.7µF
C7
2.2µF
DC+
R7
10K
DC+
R1 R2 R3
1K 1K 1K
U3
R6
1
2
3
4
8
7
6
5
5
SW1
SW2
SW3
VDD
VSS
GP0
GP1
GP2
C9
1µF
330
4
3
1
2
GP5
GP4
GP3
LED7
RED
5
5
4
3
1
2
PIC12F675
4
3
1
2
Figure 2: AAT2861 Evaluation Board Schematic.
w w w . a n a l o g i c t e c h . c o m
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2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Figure 3: AAT2861 Evaluation Board Top Side Layout.
Figure 4: AAT2861 Evaluation Board Bottom Side Layout.
w w w . a n a l o g i c t e c h . c o m
2861.2009.02.1.2
25
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Component
Part#
Description
Manufacturer
U1
U2
AAT2861IMK-x-T1
PIC12F675
High Eff. 1X/1.5X/2X CP for White LED, Triple LDO
8-bit CMOS, FLASH MCU; 8-pin PDIP
Mini TOPLED White LED; SMT
Mini TOPLED Flash LED; SMT
1.0ꢀF, 10V, X5R, 0603, Ceramic
2.2ꢀF, 10V, X5R, 0603, Ceramic
4.7ꢀF, 10V, X5R, 0603, Ceramic
1K, 5%, 1/4W; 0603
AnalogicTech
Microchip
OSRAM
Lumileds, Philips
Murata
D1-D7
DF1, DF2
C1, C2
C3, C6, C7, C8
C4, C5
R1-R3
R4
LW M673
LXCL PWF1
GRM18x
GRM18x
GRM18x
Murata
Murata
Vishay
Vishay
Vishay
Rohm
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
CMD15-21SRC/TR8
PTS645TL50
10K, 5%, 1/4W; 0603
330, 5%, 1/4W; 1206
0, 5%, 1/4W; 1206
Red LED; 1206
R6
R5
LED7
SW1-SW3, FLASH
Chicago Miniature Lamp
ITT Industries
Switch Tact, SPST, 5mm
Table 15: AAT2681 Evaluation Board Bill of Materials (BOM),
w w w . a n a l o g i c t e c h . c o m
26
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TQFN34-24
TQFN34-24
TQFN34-24
4KXYY
4LXYY
4XXYY
AAT2861IMK-1-T1
AAT2861IMK-2-T1
AAT2861IMK-3-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.
Package Information
TQFN34-243
3.000 0.050
1.700 0.050
Index Area
0.210 0.040
R(5x)
0.400 BSC
Detail “A”
Detail “A”
Bottom View
Top View
Side View
+ 0.10
- 0.00
0
0.203 REF
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.
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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.
w w w . a n a l o g i c t e c h . c o m
2861.2009.02.1.2
27
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