AAT AAT2861IMK-1-T1 Backlight/flash led driver and multiple ldo lighting management unit Datasheet

PRODUCT DATASHEET
AAT2861
ChargePumpTM
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 single-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 current 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
• Built-In Thermal Protection
• Automatic Soft Start
• -40°C to +85°C Temperature Range
• TQFN34-24 Package
The AAT2861 also offers three high-performance lownoise MicroPower™ 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
AAT2861 ideal for battery-operated applications.
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.
• Camera Enabled Mobile Devices
• Digital Still Cameras
• Multimedia Mobile Phones
Typical Application
CF1
1µF
C1+
CF2
1µF
C1- C2+
IN
VBAT
3.6V
Applications
C2-
WLEDs
OSRAM LW M673
or equivalent
VOUT
OUT
CIN
2.2µF
AAT2861-x
Flash LEDs
Lumiled LXCL-PWF1
or equivalent
COUT
2.2µF
IN
EN/SET
FL_EN
EN_ LDOA
EN_ LDOB/C
BL1
BL2
BL3
BL4
FL_EN
BL5
BL6
EN_ LDOA
BL7/FL2
FL1
EN_LDOB/C
EN/SET
LDOA
LDOB
LDOC
AGND
2861.2009.02.1.2
PGND
V LDOC
at 300mA
C LDOC
2.2µF
www.analogictech.com
V LDOB
at 300mA
C LDOB
2.2µF
V LDOA
at 300mA
C LDOA
2.2µF
1
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Pin Descriptions
2
Pin #
Symbol
1
OUT
2
C2+
3
EN/SET
4
FL_EN
5
EN_LDOA
6
EN_LDOB/C
7
AGND
8
LDOC
9
IN
10
LDOB
11
LDOA
12
BL1
13
BL2
14
BL3
15
BL4
16
BL5
17
BL6
18
BL7 (FL2)
19
FL1
20
21
22
PGND
C2C1-
23
IN
24
EP
C1+
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 AAT2861 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.
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.
LDO B and LDO C enable pin. EN_LDOB/C enables both LDO regulators B and C. The EN/SET pin must
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.
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 2.2μF 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.
LDOB is the voltage output of LDO B. Bypass LDOB to AGND with a 2.2μF or greater capacitor as close to
the AAT2861 as possible.
LDOA is the voltage output of LDO A. Bypass LDOA to AGND with a 2.2μF 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.
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.
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 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 2.2μF or larger ceramic
capacitor as close to the AAT2861 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.
www.analogictech.com
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Pin Configuration
TQFN34-24
(Top View)
PGND
C2C1IN
C1+
24
OUT
C2+
EN/SET
FL_EN
EN_LDOA
EN_LDOB/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 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
TJ
TLEAD
Description
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
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
Units
-0.3 to 6.0
-0.3 to VOUT + 0.3
-0.3 to VIN + 0.3
-0.3 to 0.3
-40 to 150
300
V
V
V
V
°C
°C
Value
Units
2.0
50
W
°C/W
Thermal Information3,4
Symbol
PD
θJA
Description
Maximum Power Dissipation
Maximum Thermal Resistance
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.
2861.2009.02.1.2
www.analogictech.com
3
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple 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, Main
Channels enabled, IBLX not included)
IIN
IN Operating Current (LDOA, LDOB and
LDOC enabled)
IN Operating Current (Only LDOA
enabled)
IN Shutdown Current
IIN(SHDN)
Over-Temperature Shutdown Threshold
TSD
Over-Temperature Shutdown Hysteresis
TSD(HYS)
Charge Pump Section
OUT Output Voltage
VOUT
OUT Maximum Output Current
IOUT(MAX)
BL1-BL7 Charge Pump Mode Transition
VIN(TH_H, BL)
Hysteresis
FL1-FL2 Charge Pump Mode Transition
VIN(TH_H, FL)
Hysteresis
Charge Pump Oscillator Frequency
fOSC
Charge Pump Soft-Start Time
tCP(SS)
BL1-BL6, BL7/FL2, FL1 LED Drivers
IBLx
BL1-BL7 Current Accuracy
IBL_x
BL1-BL7 Current Accuracy
ΔI(BLx)/
IBL(AVG)
BL1-BL7 Current Matching2
VBL_(TH)
BL1-BL7 Charge Pump Transition
Threshold
tFADE
BL1-BL7 Automatic Fade-In/Fade-Out
Timer
IFL[1]
FL1 Current Accuracy
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
ΔtFL/tFL_SET
Flash Safety Timer Period
Min
Typ
Max
Units
5.5
V
600
μA
5.5
mA
225
μA
80
μA
1.0
140
15
μA
°C
°C
5.2
800
V
mA
0.3
V
1
V
1
100
MHz
μs
2.7
EN/SET = IN, BL1-BL7 = IN, FL_EN =
EN_LDOA = EN_LDOB/C = AGND
2X Mode; EN/SET = IN, FL_EN = EN_LDOA =
EN_LDOB/C = AGND; BL1-BL7 = OPEN
EN/SET = EN_LDOA = EN_LDOB/C = IN; FL_EN
= AGND; ADDR = 3; DATA = 1; No Load
EN/SET = EN_LDOA = IN; FL_EN = EN_LDOB/C
= AGND, ADDR = 3; DATA = 1; No Load
EN/SET, FL_EN, EN_LDOA, EN_LDOB/C = AGND
VIN = 3.0V, VOUT = 4.0
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
TA = 25°C
TA = 25°C
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
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 = 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
18
20
22
mA
1.6
2
2.4
mA
3
%
0.2
V
0.75
1
1.25
s
540
600
660
mA
108
120
132
mA
1.5
5
%
0.45
V
2
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 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
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Electrical Characteristics (continued)1
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
Min
ILDO = 1mA to 200mA; TA = 25°C
ILDO = 1mA to 200mA;
TA = -40°C to +85°C
Typ
Max
Units
-1.5
1.5
%
-3.0
3.0
%
150
mA
mV
Linear Regulators
ΔVLDO[A/B/C]/
VLDO[A/B/C]
LDOA, LDOB, LDOC Output Voltage Tolerance
ILDO[A/B/C](MAX) LDOA, LDOB, LDOC Load Current
VLDO[A/B/C](DO) LDOA, LDOB, LDOC Dropout Voltage2
ΔVLDO/
LDOA, LDOB, LDOC Line Regulation
VLDO*ΔVIN
LDOA, LDOB, LDOC Power Supply Rejection Ratio
PSRR[A/B/C]
LDOA, LDOB, LDOC Auto-Discharge Resistance
ROUT_(DCHG)
EN/SET AS2Cwire and Logic Control
EN/SET, FL_EN, EN_LDOA, EN_LDOB/C Input High
VIH
Threshold Voltage
EN/SET, FL_EN, EN_LDOA, EN_LDOB/C Input Low
VIL
Threshold Voltage
EN/SET, FL_EN, EN_LDOA, EN_LDOB/C Input LeakIIN(LKG)
age Current
EN/SET Input OFF Timeout
tEN/SET(OFF)
EN/SET Input Latch Timeout
tEN/SET(LAT)
EN/SET Input LOW Time
tEN/SET(LOW)
EN/SET Minimum High Time
tENSET(H-MIN)
EN/SET Maximum High Time
tENSET(H-MAX)
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
0.09
%/V
50
20
dB
Ω
1.4
V
2.7V ≤ VIN ≤ 5.5V
EN/SET = IN = 5V
0.4
V
-1
1
μA
0.3
500
500
75
μs
μs
μs
ns
μs
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 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.
2861.2009.02.1.2
www.analogictech.com
5
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Typical Characteristics
Flash Efficiency vs. Input Voltage
100
100
90
90
Efficiency (%)
Efficiency (%)
Backlight Efficiency vs. Input Voltage
80
70
60
50
30mA/ch, VF = 3.95V
15mA/ch, VF = 3.5V
4.2mA/ch, VF = 3.4V
40
3.1
3.5
70
60
50
320mA/ch, VF = 3.25V
160mA/ch, VF = 3.15V
40
30
2.7
30
2.7
80
3.9
4.3
4.7
5.1
5.5
3.1
3.9
4.3
4.7
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)
(VIN = 3.6V; 300mA/ch)
4
4
VFL_EN
(2V/div)
2
VFL_EN
(2V/div)
2
0
VOUT
(2V/div)
VFLX
(2V/div)
4
2
600
0
0
VOUT
(2V/div)
VFLX
(2V/div)
4
2
0
600
400
IIN
(200mA/div)
200
0
400
IIN
(200mA/div)
Time (50µs/div)
6
5.1
Output Voltage (bottom) (V)
Backlight Output Current (mA)
Input Voltage (V)
3.5
200
0
Time (50µs/div)
www.analogictech.com
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
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
VFL_EN
(2V/div)
VOUT
(2V/div)
VFLX
(2V/div)
2
VEN/SET
(2V/div)
0
0V
VOUT
(2V/div)
4
2
0
600
VSINK
(2V/div)
0V
IIN
(100mA/div)
0A
400
IIN
(200mA/div)
200
0
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
(2V/div)
VSINK
(2V/div)
IIN
(200mA/div)
0V
VOUT
(2V/div)
VSINK
(2V/div)
0V
0A
IIN
(200mA/div)
0A
Time (200µs/div)
Time (200µs/div)
Operating Characteristic
(VIN = 3.2V; 20mA/ch)
(VIN = 3.2V; 20mA/ch Backlight; 1.5x Mode; COUT = 2.2µF)
VEN/SET
(2V/div)
VDIODE
(2V/div)
IIN
(200mA/div)
10
0
50
0
-50
Time (500ns/div)
Time (200µs/div)
2861.2009.02.1.2
20
Charge Pump Output Voltage
(AC coupled) (bottom) (mV)
Input Voltage (AC coupled)
(top) (mV)
Turn Off from 1.5X Mode Backlight
www.analogictech.com
7
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Typical Characteristics
(VIN = 3.6V)
10
0
20
10
0
-10
-20
Charge Pump Output Voltage
(AC coupled) (bottom) (mV)
20
LDO Output Voltage Deviatoin (%)
LDO A/B/C Load Regulation
Input Voltage (AC coupled)
(top) (mV)
Operating Characteristic
(VIN = 3.0V; 20mA/ch Backlight; 2X Mode; COUT = 2.2µF)
1.5
VOUT = 1.8V
VOUT = 3.0V
1.0
0.5
0.0
-0.5
-1.0
-1.5
0.1
1
100
1000
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
LDO Output Current
(top) (mA)
VOUT = 1.8V
VOUT = 3.3V
1.0
0.5
0.0
-0.5
-1.0
-1.5
-40
-15
10
35
60
200
100
0
-100
2.00
-200
1.90
-300
1.80
-400
1.70
-500
1.60
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)
1.82
1.81
1.80
1.79
VENLDOX (top) (V)
3.6
4.0
2.0
0.0
1.5
1.0
0.5
0.0
LDO Output (bottom) (V)
4.0
LDO Output Voltage
(bottom) (V)
4.4
Input Voltage
(top) (V)
LDO Output Voltage
(bottom) (V)
LDO Output Voltage Deviatoin (%)
Time (500ns/div)
10
1.78
Time (1ms/div)
8
Time (20µs/div)
www.analogictech.com
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
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
VEN/SET(L), VFL_EN(L),
VEN_LDOA(L), VEN_LDOB/C(L) (V)
VEN/SET(H), VFL_EN(H),
VEN_LDOA(H), VEN_LDOB/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
1.1
1.0
0.9
0.8
0.7
0.6
0.5
-40°C
25°C
85°C
0.4
0.3
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
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
Input Voltage (V)
Input Voltage (V)
EN/SET Input Latch Timeout vs. Input Voltage
EN/SET Input Off Timeout vs. Input Voltage
400
500
450
350
TOFF (µs)
TLAT (µs)
400
300
250
200
-40°C
25°C
85°C
150
100
2.7
3.1
3.5
3.9
4.3
4.7
5.1
350
300
250
200
5.5
100
2.7
Input Voltage (V)
2861.2009.02.1.2
-40°C
25°C
85°C
150
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
www.analogictech.com
9
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Functional Block Diagrams
AAT2861IMK-1-T1
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_LDOA
Main
Backlight
Current
Control
BL2
BL3
BL4
Control
Logic
BL5
5
EN_LDOB/C
Sub
Backlight
Current
Control
BL6
BL7
4
PGND
10
Flash
Control
FL1
AGND
www.analogictech.com
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
AAT2861IMK-2-T1
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
Main
Backlight
Current
Control
BL2
BL3
BL4
EN_LDOA
Control
Logic
5
EN_LDOB/C
4
PGND
2861.2009.02.1.2
Sub
Backlight
Current
Control
Flash
Control
BL5
BL6
FL2
FL1
AGND
www.analogictech.com
11
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
AAT2861IMK-3-T1
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
BL2
Main
Backlight
Current
Control
BL3
BL4
EN_LDOA
Control
Logic
BL5
5
EN_LDOB/C
4
PGND
12
Sub
Backlight
Current
Control
Flash
Control
BL6
BL7
FL1
AGND
www.analogictech.com
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Functional Description
The AAT2861 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
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.
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 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/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 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 approx-
2861.2009.02.1.2
imately 1mA steps while the flash LED current can be set
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%.
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.
Both the backlight and flash LED currents are programmed 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
The AAT2861 includes three low dropout (LDO) linear
regulators. These regulators are powered from the battery 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 LDO regulators require only a small 2.2μF 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
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.
www.analogictech.com
13
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Address
Data
THI
TLO
TLAT
TLAT
EN/SET
1
2
17
18
1
0
Address
2...
n <= 16
1
Data Reg 1
0
Data Reg 2
0
n
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 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 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 LED Backlight channels BL1-BL7 will be
enabled according to the number of data edges applied.
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 registers 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 disable each backlight or flash channel.
14
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 current 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” setting and the “Sub Fade” bit in Address 1 will be ignored.
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.
www.analogictech.com
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Address
EN/SET
Rising Edges
0
1
2
3
4
5
6
7
8
9
10
11
12
17
18
19
20
21
22
23
24
25
26
27
28
29
13
30
Function
D3
D2
D1
D0
Backlight Main/Sub ON/OFF and Fade Enable
Backlight Fade Control
Backlight Current Main, LSB's
Backlight Current Main, MSB
Backlight Current Sub, LSB's
Backlight Current Sub, MSB
LDO Disable Control
LDO A Output Voltage Control
LDO B Output Voltage Control
LDO C Output Voltage Control
Flash Current
Flash Timer Control
LED Channel Disable Control (BL1 – BL4)
LED Channel Disable Control (BL5, BL6,
BL7/FL2, FL1)
FADE_SUB
X
BLM[3]
Reserved
BLS[3]
X
X
LDOA[3]
LDOB[3]
LDOC[3]
F_HI[3]
X
OFF_BL4
FADE_MAIN
X
BLM[2]
X
BLS[2]
X
OFF_LDOC
LDOA[2]
LDOB[2]
LDOC[2]
F_HI[2]
X
OFF_ BL3
SUB_ON
FLOOR[1]
BLM[1]
MEQS
BLS[1]
X
OFF_LDOB
LDOA[1]
LDOB[1]
LDOC[1]
F_HI[1]
F_TIME[1]
OFF_ BL2
MAIN_ON
FLOOR[0]
BLM[0]
BLM[4]
BLS[0]
BLS[4]
OFF_LDOA
LDOA[0]
LDOB[0]
LDOC[0]
F_HI[0]
F_TIME[0]
OFF_ BL1
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”).
Data
Sub
Fade On
Main
Fade On
Sub
Channel
Main
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
No
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Yes
Yes
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 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
current threshold (set by Address 1) at which point the
BL channels will be turned off. The default fade-out current level is 500μA, but can be changed to 1mA, 2mA or
3mA using the data codes listed in Table 3.
Data
Fade Out Current Level (mA)
1*
2
3
4
0.50*
1.0
2.0
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 backlight channels current to one of 32 levels according to
Table 5 below.
*Denotes the default (power-on-reset) value
2861.2009.02.1.2
www.analogictech.com
15
PRODUCT DATASHEET
AAT2861
ChargePumpTM
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
8
7
6
5
4
3
2
1
0.5
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
0.5
Table 4: Backlight Main Current Control (Addresses 2 and 3).
16
www.analogictech.com
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Sub Backlight
Address
Data
Address
Data
Sub Current
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
8
7
6
5
4
3
2
1
0.5
Table 5: Backlight Sub Current Control
(Addresses 4 and 5).
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.
2861.2009.02.1.2
For example, a change from 28mA to 8mA in the Main
backlight channels should follow this procedure. First,
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.
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 settings of the Sub Channel are ignored. All backlight channels 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.
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
Table 6: Main and Sub Channel Configurations.
LDO Output Voltage Control
(Addresses 6 to 9)
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 command 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 voltages for LDOA, LDOB, and LDOC to one of 16 levels. The
available LDO output voltages are shown in Table 8.
www.analogictech.com
17
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Data
1*
2
3
4
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
LDO C
LDO B
LDO A
Controlled by
EN_LDOB/C*
Controlled by
EN_LDOB/C
Controlled by
EN_LDOB/C
Controlled by
EN_LDOB/C
Controlled by
EN_LDOB/C*
Controlled by
EN_LDOB/C
Controlled by
EN_LDOA*
5
OFF
6
OFF
OFF
OFF
Controlled by
EN_LDOA
OFF
OFF
Controlled by
EN_LDOB/C
Controlled by
EN_LDOB/C
Controlled by
EN_LDOA
7
OFF
OFF
8
OFF
OFF
Flash Driver Control (Address 10 and 11)
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-onreset value in Address 10 is set to data code 13.
Flash Current (mA) per Output
OFF
Data
AAT2861-1 or -3
AAT2861-2
Controlled by
EN_LDOA
OFF
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
40
OFF
300
280
260
240
220
200
180
160
140
120
100
80
60*
40
20
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
3.1
3.2
3.3
1.2
1.3
1.5
1.6
1.8*
2
2.2
2.5
2.6
2.7
2.8
2.9
3
3.1
3.2
3.3
1.2
1.3
1.5
1.6
1.8*
2
2.2
2.5
2.6
2.7
2.8
2.9
3
3.1
3.2
3.3
Table 8: LDO X Output Voltage
(Addresses 7, 8, and 9).
Fast turn-off response time is achieved by an active output pull-down circuit, which is enabled when the LDO
regulator is disabled.
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.
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.
*Denotes default (power-on-reset) value.
18
www.analogictech.com
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
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 automatically disabled and the flash channels will remain on
as long as the FL_EN pin remains active. Extended duration 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.
Data
Flash Time (sec)
1*
2
3
4
2*
1
0.5
Always ON
Table 10: Flash Safety Timer (Address 11).
LED Channel Disable Control
(Address 12 and 13)
Addresses 12 and 13 allow for additional programming
flexibility by allowing each LED channel to be independently 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 controls 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.
(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.)
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
OFF
OFF
OFF
OFF
OFF
OFF
OFF
Conditionally ON*
Conditionally ON
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
Conditionally ON*
Conditionally ON
OFF
OFF
Conditionally ON
Conditionally ON
OFF
OFF
Conditionally ON
Conditionally ON
OFF
OFF
Conditionally ON
Conditionally ON
OFF
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
Table 11: LED Channel Individual Disable Control, BL1-BL4 (Address 12).
*Denotes default (power-on-reset) value.
2861.2009.02.1.2
www.analogictech.com
19
PRODUCT DATASHEET
AAT2861
ChargePumpTM
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
OFF
OFF
OFF
OFF
OFF
OFF
OFF
Conditionally ON *
Conditionally ON
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
Conditionally ON*
Conditionally ON
OFF
OFF
Conditionally ON
Conditionally ON
OFF
OFF
Conditionally ON
Conditionally ON
OFF
OFF
Conditionally ON
Conditionally ON
OFF
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
Table 12: LED Channel Individual Disable Control, BL5, BL6, BL7/FL2, FL1 (Address 13).
Applications Information
Device Switching Noise Performance
LED Selection
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 specifications ranging from 2.0V to 4.7V. LED applications
may include mixed arrangements for display backlighting, 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.
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 combined to obtain a higher LED drive current without complication.
The AAT2861 operates at a fixed frequency of approximately 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 inductor-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.
Device Power Efficiency
Charge-pump efficiency discussion in the following sections 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.
*Denotes default (power-on-reset) value.
20
www.analogictech.com
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
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 forward voltage levels can differ, yet the output drive current 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 simply 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:
The AAT2861 efficiency may be quantified under very
specific conditions and is dependant upon the input voltage 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 combination 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 different efficiency values. One should refer to the following
two sections for explanations for each operational
mode.
AAT2861 charge pump conversion efficiency is defined
as the power delivered to the white LED load divided by
the input power:
η=
PLEDs VLED1 · ILED1 + ... + VLEDX · ILEDX
=
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:
η=
PLEDs X · VLEDX · ILEDX
=
PIN
VIN · IIN
2861.2009.02.1.2
η=
PLEDs VLED1 · ILED1 + ... + VLEDX · ILEDX
=
PIN
VIN · IIN
X · VLEDX · ILEDX
; X = 1, 2, 3, ..., 6 or 7 and IIN = 1.5(X · ILEDX)
VIN · IIN
VLEDX
η = 1.5V
IN
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 estimated ideal efficiency (η) for the AAT2861 in 2x mode is
as follows:
η=
η=
PLEDs VLED1 · ILED1 + ... + VLEDX · ILEDX
=
PIN
VIN · IIN
X · VLEDX · ILEDX
; X = 1, 2, 3, ..., 6 or 7 and IIN = 2(X · ILEDX)
VIN · IIN
VLEDX
η = 2V
IN
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 consumption, 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.
Capacitor Selection
X = 1, 2, 3, ..., 6 or 7 and IIN = X · ILEDX
VLEDX
η= V
IN
η=
Careful selection of all external capacitors CIN, C1, C2,
CLDO(A/B/C), and COUT is important because they will affect
turn-on time, output ripple and transient performance.
Optimum performance will be obtained when low ESR
www.analogictech.com
21
PRODUCT DATASHEET
AAT2861
ChargePumpTM
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.
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 counterparts. 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 connection damage.
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 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 COG materials. NPO and C0G materials
typically have tight tolerance and are stable over temperature. 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.
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
AVX
TDK
Murata
Taiyo Yuden
These larger size capacitors can improve circuit transient
response 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.
Figures 2 and 3 illustrate an example PCB layout. The
bottom of the package features an exposed metal paddle. The exposed paddle acts, thermally, to transfer heat
from the chip and, electrically, as a ground connection.
The junction-to-ambient thermal resistance (θJA) for the
connection can be significantly reduced by 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.
Part Number
Value
Voltage
0603ZD105K
0603ZD225K
C1608X5R1E105K
C1608X5R1C225K
C1608X5R1A475K
GRM188R61C105K
GRM188R61A225K
LMK107BJ475KA
1μF
2.2μF
1μF
2.2μF
4.7μF
1μF
2.2μF
4.7μF
10
10
25
16
10
16
10
10
be connected
kept short to
coupling. The
be placed as
Temp. Co.
Case
X5R
0603
X5R
0603
X5R
0603
X5R
0603
Table 13: Surface Mount Capacitors.
22
www.analogictech.com
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Evaluation Board User Interface
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 combinations. Table 14 indicates the function of each button or
button combination.
To power-on the evaluation board, connect a power supply or battery to the DC- and DC+ terminals. A red LED
indicates that power is applied.
Button(s) Pushed
SW1
SW2
SW3
FLASH
The evaluation board is made flexible so that the user
can disconnect the enable line from the microcontroller
and apply external enable signal. External enable signal
must be applied to the EN/SET pin.
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+).
The LDO loads can be connected directly to the evaluation board. For adequate performance, be sure to connect the load between LDOA/LDOB/LDOC and DC- as
opposed to some other GND in the system.
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.
[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 sequence for Sub channels. When these sequences are finished the program will restart fade out sequence
for all Main and Sub channels.
[Push/Release once] Flash channels are programmed with maximum current and timer. With every subsequent push/release the flash current is decreased according to Table 9. The FLASH button needs to be
pressed down simultaneously.
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.
2861.2009.02.1.2
www.analogictech.com
23
PRODUCT DATASHEET
AAT2861
ChargePumpTM
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
C8
2.2µF
FLASH
5
41
32
DC+
R4
10K
U1
AAT2861-X
C1+ IN C1- C2- PGND
24
23
22
20
21
1
OUT
FL1
19
2
C2+
BL7/FL2
18
3
EN/SET
BL6
17
4
FL_EN
BL5
16
5
EN_LDOA
BL4
15
6
EN_LDOB/C
BL3
14
7
AGND
BL2
13
LDOC
IN
8
LDOB LDOA BL1
9
10
11
C6
2.2µF
C5
4.7µF
C7
2.2µF
D6 D5 D4 D3 D2 D1
12
C3
2.2µF
DC+
R7
10K
DC+
R1
1K
R2
1K
R3
1K
SW1
5
4
3
1
2
4
3
1
2
4
3
1
2
SW2
5
1
2
3
4
U3
VDD
VSS
GP5
GP0
GP4
GP1
GP3
GP2
PIC12F675
8
7
6
5
C9
1µF
R6
330
LED7
RED
SW3
5
Figure 2: AAT2861 Evaluation Board Schematic.
24
www.analogictech.com
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
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.
2861.2009.02.1.2
www.analogictech.com
25
PRODUCT DATASHEET
AAT2861
ChargePumpTM
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Component
Part#
Description
Manufacturer
U1
U2
D1-D7
DF1, DF2
C1, C2
C3, C6, C7, C8
C4, C5
R1-R3
R4
R6
R5
LED7
SW1-SW3, FLASH
AAT2861IMK-x-T1
PIC12F675
LW M673
LXCL PWF1
GRM18x
GRM18x
GRM18x
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
CMD15-21SRC/TR8
PTS645TL50
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
1.0μF, 10V, X5R, 0603, Ceramic
2.2μF, 10V, X5R, 0603, Ceramic
4.7μF, 10V, X5R, 0603, Ceramic
1K, 5%, 1/4W; 0603
10K, 5%, 1/4W; 0603
330, 5%, 1/4W; 1206
0, 5%, 1/4W; 1206
Red LED; 1206
Switch Tact, SPST, 5mm
AnalogicTech
Microchip
OSRAM
Lumileds, Philips
Murata
Murata
Murata
Vishay
Vishay
Vishay
Rohm
Chicago Miniature Lamp
ITT Industries
Table 15: AAT2681 Evaluation Board Bill of Materials (BOM),
26
www.analogictech.com
2861.2009.02.1.2
PRODUCT DATASHEET
AAT2861
ChargePumpTM
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
0.400 ± 0.050
R(5x)
2.700 ± 0.050
4.000 ± 0.050
0.210 ± 0.040
0.400 BSC
Detail “A”
Detail “A”
Bottom View
0.750 ± 0.050
Top View
0
+ 0.10
- 0.00
0.203 REF
Side View
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.
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.
2861.2009.02.1.2
www.analogictech.com
27