DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
General Description
Features
The AAT2866 is a highly integrated charge pump-based
lighting management unit (LMU) offering eight LED
channels with three linear regulators optimized for single-cell lithium-ion/polymer systems. The charge pump
provides power for all LED outputs and multiple backlight
and flash LED configurations are available. The backlight
LED channel outputs are programmable up to 31mA and
the total flash LED output current can be programmed
up to 600mA.
• Input Voltage Range: 2.7V to 5.5V
• AS2Cwire Serial Interface
• Tri-Mode Charge Pump
▪ Drives up to Eight LEDs
• Programmable Backlight Current by:
▪ AS2Cwire Interface
• 31mA Maximum Current per Channel
• 32 Linear Current Settings
• Independent Main/Sub Settings
▪ PWM Control
• All Channels BL1-BL6 (default)
• Main Backlight BL1-BL4 (optional)
• All Channels BL1-BL7 (AAT2866-3)
• 60Hz to 100kHz
▪ Programmable Flash Current
• 600mA Total Flash Current
• 16 Linear Current Settings
• 2 Channel Configuration
• 1MHz Switching Frequency
• Automatic Soft Start
• Three Linear Regulators
▪ 300mA Output Current
▪ 150mV Dropout
▪ Programmable Control from 1.2V to 3.3V
▪ Output Auto-Discharge for Fast Shutdown
• Built-In Thermal Protection
• Automatic Soft Start
• -40°C to +85°C Temperature Range
• TQFN34-24 Package
Skyworks' AS2Cwire™ 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
separate flash enable and programmable safety timer are
included for easy flash control. Backlight current matching is better than 3% for uniform display brightness, and
flash current matching is better than 5% for uniform
power dissipation. As an alternative, the main backlight
LED's output current can be controlled via pulse width
modulation (PWM).
The AAT2866 also offers three high-performance lownoise MicroPower™ low dropout (LDO) linear regulators.
The regulators output voltages are set through the
AS2Cwire serial interface. Each LDO can supply up to
300mA load current and ground-pin current is only 80µA
making the AAT2866 ideal for battery-operated applications.
The AAT2866 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
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202262A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012
1
DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
Typical Application
CF1
1µF
C1+
CF2
1µF
C1- C2+
IN
VBAT
3.6V
CIN
2.2µF
PWMM
C2OUT
VOUT
COUT
2.2µF
AAT2866
IN
PWMM
BL1
BL2
BL3
BL4
EN/SET
EN/SET
BL5
BL6
BL7/FL2
FL_EN
FL_EN
FL1
LDOA
EN_LDOA/B/C
EN_LDOA/B/C
LDOB
2
COUTA
2.2µF
VLDOB
at 300mA
COUTB
2.2µF
LDOC
AGND
VLDOA
at 300mA
PGND
VLDOC
at 300mA
COUTC
2.2µF
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202262A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012
DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
Pin Descriptions
Pin #
Symbol
Function
1
OUT
O
2
C2+
I
3
EN/SET
I
4
FL_EN
I
5
PWMM
I
6
EN_LDOA/B/C
I
7
AGND
GND
8
LDOC
O
9
IN
I
10
LDOB
O
11
LDOA
O
12
BL1
O
13
BL2
O
14
BL3
O
15
BL4
O
16
BL5
O
17
BL6
O
18
BL7/FL2
O
19
FL1
O
20
21
22
PGND
C2C1-
GND
I
I
23
IN
I
24
C1+
I
EP
GND
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 2.2μF or larger ceramic capacitor as close to the AAT2866 as possible.
Positive terminal of charge pump capacitor 2. Connect the 1μF 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 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.
PWM input pin. Apply a PWM signal of varying duty cycle to modulate the LED current on
BL1, BL2, BL3, BL4, BL5 & BL6 (Default). PWM frequency can vary up to 100kHz. The LED
current maximum will be set at the default setting if no programming is applied. If not used,
connect PWMM to IN.
LDOA, LDOB and LDOC enable pin. EN_LDOA/B/C enables all LDO regulators A. The EN/SET
pin must also be pulled high for the LDO regulators to be enabled. The EN_LDOA/B/C input
can be overwritten via the AS2Cwire interface to disable either LDOA or LDOB or LDOC.
Analog ground. Connect AGND to PGND at a single point as close to the AAT2866 as possible.
LDOC is the voltage output of LDOC. Bypass LDOC to AGND with a 2.2μF or greater capacitor as close to the AAT2866 as possible.
Input power pin for all three LDOs. Connect Pin 11 to Pin 23 with as short a PCB trace as
practical.
LDOB is the voltage output of LDOB. Bypass LDOB to AGND with a 2.2μF or greater capacitor as close to the AAT2866 as possible.
LDOA is the voltage output of LDOA. Bypass LDOA to AGND with a 2.2μF or larger ceramic
capacitor as close to the AAT2866 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.
AAT2866: 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.
AAT2866-3: 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.
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.
Power ground. Connect PGND to AGND at a single point as close to the AAT2866 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 2.2μF or
larger ceramic capacitor as close to the AAT2866 as possible.
Positive terminal of charge pump capacitor 1. Connect the 1μF charge pump capacitor 1
from C1+ to C1-.
Exposed paddle (bottom) Connect to PGND/AGND as close to the AAT2866 as possible.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202262A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012
3
DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
Pin Configuration
TQFN34-24
(Top View)
PGND
C2C1IN
C1+
24
OUT
C2+
EN/SET
FL_EN
PWMM
EN_LDOA/B/C
AGND
23
22
21
20
1
19
2
18
3
17
4
16
5
15
6
14
7
13
8
9
10
11
FL1
BL7/FL2
BL6
BL5
BL4
BL3
BL2
12
BL1
LDOA
LDOB
IN
LDOC
Part Number Description1
Backlight LED Outputs
Part Number
Main
Sub
Flash LED Output
AAT2866IMK-T1
AAT2866IMK-3-T1
6/4
5
0/2
2
2
1
Absolute Maximum Ratings2
TA = 25°C unless otherwise noted.
Symbol
Description
IN, OUT, BL1, BL2, BL3, BL4, BL5, BL6, FL1, BL7/FL2 Voltage to AGND
C1+, C2+ Voltage to AGND
C1-, C2-, LDOA, LDOB, LDOC, EN/SET, FL_EN, EN_LDOA/B/C, PWMM Voltage to AGND
PGND Voltage to AGND
Value
Units
-0.3 to 6.0
-0.3 to VOUT + 0.3
-0.3 to VIN + 0.3
-0.3 to 0.3
V
Thermal Information3, 4
Symbol
ΘJA
PD
TJ
TLEAD
Description
Thermal Resistance
Maximum Power Dissipation
Operating Junction Temperature Range
Maximum Soldering Temperature (at Leads)
Value
Units
50
2
-40 to 150
300
OC/W
W
°C
1. Backlight Main and Sub are configured to be equal by default. Main and Sub can be programmed via AS2Cwire to be 4 Main and 2 Sub . For more information, see the Applications
Information section of this datasheet.
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.
4
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202262A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012
DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
Electrical Characteristics1
VIN = 3.6V; CIN = COUT = 2.2μF; C1 = C2 = 1µF; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA =
25°C.
Symbol
Description
Conditions
VIN
IN Operating Voltage Range
IN Operating Current (1x mode,
Main Channels enabled, IBLX not
included)
IN Operating Current (2x mode,
IIN
Main Channels enabled, IBLX not
included)
IN Operating Current (LDOA,
LDOB and LDOC enabled)
IIN(SHDN)
IN Shutdown Current
Over-Temperature Shutdown
TSD
Threshold
Over-Temperature Shutdown
TSD(HYS)
Hysteresis
Charge Pump Section
VOUT
OUT Output Voltage
IOUT(MAX)
OUT Maximum Output Current
BL1-BL7 Charge Pump Mode
VIN(TH_H, BL)
Transition Hysteresis
FL1-FL2 Charge Pump Mode
VIN(TH_H, FL)
Transition Hysteresis
fOSC
Charge Pump Oscillator Frequency
tCP(SS)
Charge Pump Soft-Start Time
BL1-BL7, FL1, FL2 LED Drivers
IBLx
BL1-BL7 Current Accuracy
IBL_x
BL1-BL7 Current Accuracy
IBL_(10%)
ΔI(BLx)/
IBL(AVG)
VBL_(TH)
BL1-BL7 PWM Current Accuracy
BL1-BL7 Current Matching
2
BL1-BL7 Charge Pump Transition
Threshold
IFL[1]
FL1,FL2 Current Accuracy
IFL[1](DATA13)
FL1, FL2 Current Accuracy
ΔI(FLx)/
IFL(AVG)
FL1-FL2 Current Matching
VFL[1/2](TH)
FL1,FL2 Charge Pump Transition
Threshold
ΔtFL/tFL_SET
Flash Safety Timer Period
Min
Typ
Max
Units
5.5
V
600
µA
5.5
mA
225
µA
1.0
µA
2.7
EN/SET = PWMM = BL1-BL7 = IN, FL_EN =
EN_LDOA/B/C = AGND;
2x Mode; EN/SET= PWMM = IN, FL_EN =
EN_LDOA/B/C = AGND; BL1-BL7 = OPEN;
ADDR=12, DATA=15; ADDR=13, DATA=16
EN/SET = PWMM = EN_LDOA/B/C = IN; FL_EN =
AGND; ADDR = 0; DATA = 6; No Load
EN/SET, FL_EN, EN_LDOA/B/C, PWMM = AGND
VIN = 3.0V, VOUT = 4.0V
EN/SET = IN; VIN – VF = 1V; ADDR=3, DATA=2;
ADDR=2, DATA=12
EN/SET = FL_EN = IN; VIN – VF = 1V; ADDR=10,
DATA=1
TA = 25°C
TA = 25°C
EN/SET = IN; VIN – VF = 1V; ADDR=3, DATA=3;
ADDR=2, DATA=12
EN/SET = IN; VIN – VF = 1V; ADDR=3, DATA=4;
ADDR=2, DATA=14
DC=10%; fPWM=10kHz; VIN-VF=1.5V
EN/SET = IN; VIN – VF = 1V; ADDR=3, DATA=3;
ADDR=2, DATA=12
EN/SET = IN; VIN – VF = 1V; ADDR=3, DATA=3;
ADDR=2, DATA=12
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
140
°C
15
°C
5.2
800
V
mA
0.3
V
1
V
1
100
MHz
µs
18
20
22
mA
1.6
2
2.4
mA
2.5
mA
3
%
0.2
V
270
300
330
mA
54
60
66
mA
1.5
5
%
0.45
V
2
2.5
s
1. The AAT2866 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.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202262A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012
5
DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
Electrical Characteristics1
VIN = 3.6V; CIN = COUT = 2.2μF; C1 = C2 = 1µF; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA =
25°C.
Symbol
Description
Linear Regulators
ΔVLDO[A/B/C]/
LDOA, LDOB, LDOC Output Voltage
VLDO[A/B/C]
Tolerance
LDOA, LDOB, LDOC Maximum Load
ILDO[A/B/C](MAX)
Current
VLDO[A/B/C](DO)
LDOA, LDOB, LDOC Dropout Voltage2
∆VLDO/
LDOA, LDOB, LDOC Line Regulation
VLDO*∆VIN
LDOA, LDOB, LDOC Power Supply
PSRR[A/B/C]
Rejection Ratio
LDOA, LDOB, LDOC Auto-Discharge
RLDO_(DCHG)
Resistance
AS2Cwire and Logic Control
EN/SET, FL_EN, PWMM, EN_LDOA/
VIH
B/C Input High Threshold Voltage
EN/SET, FL_EN, PWMM, EN_LDOA/
VIL
B/C Input Low Threshold Voltage
IIN(LKG)
EN Input Leakage Current
tEN/SET(OFF)
EN/SET Input OFF Timeout
tEN/SET(LAT)
EN/SET Input Latch Timeout
tEN/SET(LOW)
EN/SET Input LOW Time
tENSET(H-MIN)
EN/SET Minimum High Time
tENSET(H-MAX)
EN/SET Maximum High Time
Conditions
Min
ILDO = 1mA to 200mA; TA = 25°C
ILDO = 1mA to 200mA; TA = -40°C to +85°C
-1.5
-3.0
Typ
Max
Units
1.5
3.0
%
200
VLDO[A/B/C] ≥ 3.0V; ILDO = 150mA
75
VIN = (VLDO[A/B/C] + 1V) to 5V
ILDO[A/B/C] =10mA, 1kHz
2.7V ≤ VIN ≤ 5.5V
mA
mV
0.09
%/V
50
dB
1.5
kΩ
1.4
V
2.7V ≤ VIN ≤ 5.5V
EN/SET = PWMM = EN_LDOA/B/C = IN = 5V
150
-1
0.3
0.4
V
1
500
500
75
μA
µs
µs
µs
ns
µs
50
75
1. The AAT2866 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. VDO[A/B/C] is defined as VIN – LDO[A/B/C] when LDO[A/B/C] is 98% of nominal.
6
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202262A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012
DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
Typical Characteristics
Flash Efficiency vs. Input Voltage
100
100
90
90
80
80
Efficiency (%)
Efficiency (%)
Backlight Efficiency vs. Input Voltage
70
60
50
30mA/ch, VF = 3.95V
15mA/ch, VF = 3.5V
4.2mA/ch, VF = 3.4V
40
30
2.7
3.1
3.5
60
50
320mA/ch, VF = 3.25V
160mA/ch, VF = 3.15V
40
3.9
4.3
4.7
5.1
30
2.7
5.5
Input Voltage (V)
3.1
3.5
3.9
4.3
4.7
5.1
5.5
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
4.0
VEN/SET (top) (V)
21
20
19
Channel 1 - Channel 6/7
18
2.0
4.0
0.0
3.0
2.0
1.0
17
0.0
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)
VOUT
(2V/div)
VFLX
(2V/div)
(VIN = 3.6V; 300mA/ch)
4
VFL_EN
(2V/div)
4
VFL_EN
(2V/div)
2
0
VOUT
(2V/div)
VFLX
(2V/div)
4
2
600
0
2
0
4
2
0
600
400
IIN
(200mA/div)
400
IIN
(200mA/div)
200
0
Time (50µs/div)
Output Voltage (bottom) (V)
Backlight Output Current (mA)
70
200
0
Time (50µs/div)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202262A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012
7
DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
Typical Characteristics
Turn On to 2x Mode Flash
Turn On to 1x Mode Backlight
(VIN = 2.8V; 300mA/ch)
4
VFL_EN
(2V/div)
VOUT
(2V/div)
VFLX
(2V/div)
(VIN = 4.2V; 20mA/ch)
2
0
4
2
0
600
400
IIN
(200mA/div)
200
0
Time (50µs/div)
EN/SET
(2V/div)
0V
VCP
(2V/div)
0V
VBLx
(2V/div)
0V
IIN
(100mA/div)
0A
Time (100µs/div)
Turn On to 1.5x Mode Backlight
Turn On to 2x Mode Backlight
(VIN = 3.2V; 20mA/ch)
EN/SET
(2V/div)
VCP
(2V/div)
VBLx
(2V/div)
IIN
(100mA/div)
(VIN = 2.7V; 20mA/ch)
EN/SET
(2V/div)
0V
VCP
(2V/div)
VBLx
(2V/div)
0V
0V
0V
0V
IIN
(200mA/div)
0A
Time (100µs/div)
Operating Characteristic
(VIN = 3.2V; 20mA/ch Backlight; 1.5x Mode; COUT = 2.2µF)
VEN/SET
(2V/div)
VDIODE
(2V/div)
IIN
(200mA/div)
20
10
0
50
0
Charge Pump Output Voltage
(AC coupled) (bottom) (mV)
Input Voltage (AC coupled)
(top) (mV)
(VIN = 3.2V; 20mA/ch)
Time (200µs/div)
0A
Time (200µs/div)
Turn Off from 1.5x Mode Backlight
8
0V
-50
Time (500ns/div)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202262A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012
DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
Typical Characteristics
Operating Characteristic
LDO Load Regulation vs. Output Current
10
0
20
10
0
-10
-20
Time (500ns/div)
1.8
Output Error (%)
20
(VOUT = 1.2V)
Charge Pump Output Voltage
(AC coupled) (bottom) (mV)
Input Voltage (AC coupled)
(top) (mV)
(VIN = 3.0V; 20mA/ch Backlight; 2x Mode; COUT = 2.2µF)
-1.0
60
85
Temperature (°C)
0
-100
2.00
-200
1.90
-300
1.80
-400
1.70
-500
1.60
Time (20µs/div)
LDO A/B/C Line Transient Response
LDO A/B/C Turn On Characteristic
1.80
1.79
VENLDOX (top) (V)
Input Voltage
(top) (V)
1.81
4.0
2.0
0.0
1.5
1.0
0.5
0.0
1.78
Time (1ms/div)
LDO Output (bottom) (V)
1.82
(VLDO = 1.8V; VIN = 3.6V; CLDO = 2.2µF)
LDO Output Voltage
(bottom) (V)
3.6
1000
100
(VIN = 3.6V to 4.2V; ILDO = 10mA; VOUT = 1.8V; CLDO = 2.2µF)
4.0
100
200
4.4
10
Load Current (mA)
LDO Output Current
(top) (mA)
LDO Output Voltage Deviatoin (%)
-0.5
35
1
LDO Output Voltage
(bottom) (V)
0.0
10
-1.2
LDO A/B/C Load Transient Response
0.5
-15
-0.6
(ILDO = 10mA to 200mA; VIN = 3.6V; VLDO = 1.8V; CLDO = 2.2µF)
VOUT = 1.8V
VOUT = 3.3V
-1.5
-40
0.0
(VIN = 3.6V; ILDO = 0mA)
1.0
0.6
-1.8
0.1
LDO A/B/C Output Voltage vs. Temperature
1.5
85°C
25°C
-40°C
1.2
Time (20µs/div)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202262A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012
9
DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
Typical Characteristics
EN/SET, FL_EN, PWMM, EN_LDOA/B/C
High Threshold Voltage vs. Input Voltage
EN/SET, FL_EN, PWMM, EN_LDOA/B/C
Low Threshold Voltage vs. Input Voltage
1.2
VEN/SET(L), VFL_EN(L),
VPWMM(L), VEN_LDOA/B/C(L) (V)
VEN/SET(H), VFL_EN(H),
VPWMM(H), VEN_LDOA/B/C(H) (V)
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
-40°C
25°C
85°C
0.6
0.5
0.8
0.7
0.6
0.5
-40°C
25°C
85°C
0.4
0.3
Input Voltage (V)
EN/SET Input Off Timeout vs. Input Voltage
400
500
450
350
400
300
TOFF (µs)
TLAT (µs)
0.9
EN/SET Input Latch Timeout vs. Input Voltage
250
200
-40°C
25°C
85°C
150
100
2.7
1.0
0.2
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
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
Input Voltage (V)
1.1
3.1
3.5
3.9
4.3
Input Voltage (V)
4.7
5.1
350
300
250
200
-40°C
25°C
85°C
150
100
2.7
5.5
3.1
3.5
3.9
4.3
4.7
Input Voltage (V)
10
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202262A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012
5.1
5.5
DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
Functional Block Diagram
IN
IN
C1C1+
C2-
LDOA
1x/1.5x/2x
Tri -mode
Charge Pump
C2+
LDOB
OUT
LDOC
8
REF
BL1
EN/SET
5
FL_EN
EN_LDO A/B/C
Main
Backlight
Current
Control
BL2
BL3
BL4
Control
Logic
5
PWMM
4
PGND
Sub
Backlight
Current
Control
Flash
Control
BL5
BL6
BL7/FL2
FL1
AGND
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202262A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012
11
DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
Functional Description
The AAT2866 is a highly integrated backlight and photoflash 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
get their power from the same input and produce regulated output voltages between 1.2V and 3.3V. Control of
the LEDs and the LDO output voltages are through an
AS2Cwire serial interface for easy programming. In addition, BL1-BL6 (AAT2866) or BL1-BL7 (AAT2866-3) LED
current can be controlled via an external PWM signal.
LED Drivers
The AAT2866 drives six backlight LEDs up to 31mA each
and a total of 600mA flash current through two channels.
The LEDs are driven from a charge pump to insure that
constant current is maintained for all possible LED forward voltages over the entire battery voltage range. The
charge pump automatically 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 1μF ceramic capacitors. 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 charge pump is controlled by the voltage across the
LED current sinks. When any one of the active backlight
current sink voltages drops below 200mV or the flash
current sink 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 AAT2866 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 300mV mode-transition
hysteresis that prevents the charge pump from oscillating between modes.
LED Current Control
Both the backlight and flash LED currents are controlled
through the AS2Cwire serial interface. The backlight LED
current can be set between 0.5mA and 31mA in approximately 1mA steps while the flash LED current can be set
between 0 to 300mA in 20mA steps for each channel.
12
The backlight LED currents match to within 3% while the
flash LED currents match to within 5%.
To eliminate the latency of the AS2Cwire serial interface,
the flash LED is enabled through a dedicated input, FL_
EN. The AAT2866 also includes a safety timer that prevents overstress of the flash LEDs. This is important
because many flash LEDs operate for a brief period
beyond their steady-state operating limitations. If the
flash driving hardware and/or software fails to turn the
LED off, the safety timer insures that the LED or other
circuitry is not damaged.
Both the backlight and flash LED currents are programmed through the AS2Cwire serial interface including
the flash safety timer. See the “AS2Cwire Serial Interface
Programming” section for more information on setting
the LED currents.
PWM Controlled Dimming
As an alternative to digital dimming via the AS2Cwire
serial interface, the AAT2866 also provides an additional
pin, PWMM, which allows the user to control BL1-BL6
(AAT2866) or BL1-BL7 (AAT2866-3) or the Main BL1-BL4
(AAT2866) or BL1-BL5 (AAT2866-3) (optional, when
MEQS is deactivated) backlight LEDs with a PWM signal.
The Sub backlight channels BL5-BL6 (AAT2866) or BL6BL7 (AAT2866-3) current is set by AS2Cwire interface.
The PWM signal will modulate the LED current set by
AS2Cwire programming or the AAT2866 default current.
In this mode the minimum PWM frequency is 60Hz. PWM
frequencies as high as 100kHz can be used.
LDO Regulators
The AAT2866 family includes three low dropout (LDO)
linear regulators. These regulators are powered from the
battery and produce fixed output voltages 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 pin EN_LDOA/B/C. Additionally, the AS2Cwire
interface allows the LDO regulators to be enabled independently when the EN_LDOA/B/C pin is pulled high.
All LDO regulators require only small 2.2μF ceramic output capacitors for stability. If improved load transient
response is required, larger-valued capacitors can be
used without stability degradation.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202262A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012
DATA SHEET
AAT2866
Backlight/Flash LED Driver and Triple LDO Lighting Management Unit
AS2Cwire Serial Interface Protocol
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 LED Backlight channels BL1-BL6 (AAT2866)
or BL1-BL7 (AAT2866-3) will be enabled according to the
number of data edges applied.
The AAT2866 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.
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
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 EN/SET rising edges identifying
a particular address, followed by a pause with EN/SET
held high for the tLAT time-out 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
When EN/SET is held low for a time longer than tOFF
(500µs), the AAT2866 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 AAT2866’s AS2C programming Address registers are
listed in Table 1. There are 13 active Address registers;
four control the three LDOs, four control the backlight
LED configuration/control, two control the flash current
and timer control, two are used to individually disable
each backlight or flash channel, and one is reserved for
test purposes.
Address
Data
THI
TLO
TLAT
TLAT
EN/SET
1
Address
2
17
18
1
0
2...
n
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