AAT2803 - Skyworks Solutions, Inc.

DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
General Description
Features
The AAT2803 is a dual charge pump designed to support
both white LED backlight and flash applications for systems operating with lithium-ion/polymer batteries. The
backlight charge pump is capable of driving up to six LEDs
at a total of 180mA. The current sinks may be operated
in group or in parallel for driving higher current LEDs. To
maximize power efficiency, the charge pump operates in
1X, 1.5X, or 2X mode, where the mode of operation is
automatically selected by comparing the forward voltage
of each LED with the input voltage. Skyworks' AS2Cwire™
(Advanced Simple Serial Control™) serial digital input is
used to enable, disable, and set current for each LED with
a 16-level logarithmic scale plus four low-current settings
down to 50μA for optimized efficiency, with a low housekeeping current of only 50μA.
• VIN Range: 2.7V to 5.5V
• Dual Charge Pump:
▪ Flash: Charge Pump Doubler
▪ Backlight: Tri-Mode Charge Pump
• Backlight Charge Pump:
▪ Programmable Current With Single GPIO
▪ 16 Current Steps
▪ 15/20/30mA Max Current
▪ Four Low Current Settings
▪ Individual Main/Sub-Group Control
▪ Low IQ (50μA) for Low-Current Mode
▪ Drives Six Channels of LEDs
• Flash Charge Pump:
▪ Regulated VOUT_FL 4.5/5.0 Volts
▪ Up to 300mA of Current for Flash
• 1MHz Constant Switching Frequency
• Independent Backlight/Flash Control
• Built-In Thermal Protection
• Built-In Auto-Disable for Open Circuit
• Automatic Soft Start
• IQ <1μA in Shutdown
• Available in QFN44-24 Package
The flash charge pump is a charge pump doubler with a
regulated output voltage. It is designed to deliver 120mA
of continuous current and up to 300mA of pulsed current. It has an independent enable pin for improved
power savings.
The AAT2803 is equipped with built-in protection, shortcircuit, and auto-disable for load short-circuit condition.
Built-in soft-start circuitry prevents excessive inrush current during start-up. A low-current shutdown feature
disconnects the load from VIN and reduces quiescent current to less than 1μA.
Applications
•
•
•
•
The AAT2803 is available in a Pb-free, space-saving,
thermally enhanced 24-pin 4x4mm QFN package and is
rated over the -40°C to +85°C temperature range.
Color (RGB) Lighting
Programmable Current Sink
White LED Backlighting
White Photo Flash for Digital Still Cameras
Typical Application
C1
1µF
C1+
VIN
V IN
C2
1µF
C1- C2+
C3
1µF
C2- C3 + C3 VOUT
Flash
COUT
1µF
CIN
1µF
AAT2803
Backlight
D6
EN_FL
EN/SET
ENFL
EN/SET
GND
D5
D4
D3
D2
D1
COUT
1µF
D6
D5
D4
D3
D2
D1
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
1
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Pin Descriptions
Pin #
Symbol
Function
1
2
3
4, 14
C1C1+
VOUT_FL
VIN
5
EN_FL
6, 7, 23
8
9
10
11
12
13, 15, 24
16
17
18
19
20
21
N/C
VOUT_BL
C2+
C3+
C3C2GND
D1
D2
D3
D5
D4
D6
22
EN/SET
Flying capacitor 1 negative terminal.
Flying capacitor 1 positive terminal. Connect a 1μF capacitor between C1+ and C1-.
Flash output voltage. Requires 1μF capacitor connected between this pin and ground.
Input power supply. Requires 1μF capacitor connected between this pin and ground.
Enable pin for flash charge pump. For normal operation, connect to VIN. When connected low, the flash
charge pump shuts down and consumes less than 1μA of current.
No connect.
Backlight output voltage charge pump. Requires 1μF capacitor connected between this pin and ground.
Flying capacitor 2 positive terminal. Connect a 1μF capacitor between C2+ and C2-.
Flying capacitor 3 positive terminal. Connect a 1μF capacitor between C3+ and C3-.
Flying capacitor 3 negative terminal.
Flying capacitor 2 negative terminal.
Ground.
Current sink input #1.
Current sink input #2.
Current sink input #3.
Current sink input #5.
Current sink input #4.
Current sink input #6.
AS2Cwire serial interface control pin for backlight charge pump. It controls the current settings for all six
channels. This pin should not be left floating.
Exposed paddle (bottom); connect to GND directly beneath package.
EP
Pin Configuration
QFN44-24
(Top View)
D5
D4
D6
EN/SET
N/C
GND
19
20
21
22
23
24
C1C1+
VOUT_FL
VIN
EN_FL
N/C
1
18
2
17
3
16
AAT2803
4
15
5
14
6
13
D3
D2
D1
GND
VIN
GND
12
11
9
10
8
7
C2C3C3+
C2+
VOUT_BL
N/C
2
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Absolute Maximum Ratings1
Symbol
VIN
VEN/SET
TJ
TLEAD
Description
Input Voltage
EN/SET to GND Voltage
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
Units
-0.3 to 6
-0.3 to VIN + 0.3
-40 to 150
300
V
V
°C
°C
Value
Units
2.0
50
W
°C/W
Thermal Information2
Symbol
PD
JA
Description
Maximum Power Dissipation
Maximum Thermal Resistance
3
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions
specified is not implied. Only one Absolute Maximum Rating should be applied at any one time.
2. Mounted on an FR4 board.
3. Derate 6.25mW/°C above 25°C.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
3
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Electrical Characteristics1
VIN = 3.6V, CIN = COUT = C1 = C2 = C3 = 1.0μF; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA =
25°C.
Symbol
VIN
ICC
ISHDN
IDX
I(D-Match)
VTH
VOUT
IOUT
TSS
FCLK
VEN(L)
VEN(H)
TEN/SET LO
TEN/SET_HI_MIN
TEN/SET_HI_MAX
TOFF
TLAT
IEN/SET;EN_FL
Description
Conditions
Operation Range
Operating Current
Shutdown Current
ISINK Average Current Accuracy2
Current Matching Between Any
Two Current Sink Inputs3, 4
1X to 1.5X or 1.5X to 2X Transition Threshold at Any DX Pin
Output Voltage (Flash Charge
Pump)5
Max Continuous Output Current
(Flash Charge Pump)5
Max Pulsed Output Current5
Soft-Start Time
Clock Frequency
Enable Threshold Low
Enable Threshold High
EN/SET Low Time
Minimum EN/SET High Time
Maximum EN/SET High Time
EN/SET Off Timeout
EN/SET Latch Timeout
Input Leakage
Min
Typ
2.7
1X Mode, 3.0 £ VIN £ 5.5, Active, No Load
Current; EN/SET = VIN; EN_FL= GND
1.5X Mode, 3.0 £ VIN £ 5.5, Active, No Load
Current; EN/SET = VIN; EN_FL= GND
2X Mode, 3.0 £ VIN £ 5.5, Active, No Load
Current; EN/SET = VIN; EN_FL = GND
VOUT_FLASH = 5V; EN/SET = GND; EN_FL = VIN
50μA Setting, 1X Mode; EN/SET = VIN;
EN_FL = GND
EN/SET = 0
ISET = 30mA, TA = 25°C
ISET = 4.1mA, TA = 25°C
Units
5.5
V
0.3
1
1.0
3.0
2.0
3.7
2.0
4.5
50
27
3.69
VF:D1:D4 = 3.6V
3.0< VIN < 5V, IOUT = 120mA; EN_FL = VIN
4.3
VIN = 3.3V; VOUT = 4.5V; EN_FL = VIN
120
VIN = 3.6V; VOUT = 4.5V; IPULSED = 250ms
Backlight Charge Pump
Flash Charge Pump
VIN = 2.7V
VIN = 5.5V
Max
30
4.1
μA
1.0
33
4.51
μA
mA
0.5
%
150
mV
4.5
4.7
V
mA
300
100
200
1.0
μs
0.4
1.4
0.3
75
50
VEN/SET;EN_FL = 5V; VIN = 5V
mA
-1.0
75
500
500
1.0
MHz
V
V
μs
ns
μs
μs
μs
μA
1. The AAT2803 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. Determined by the average of all active channels.
3. Current matching is defined as the deviation of any sink current from the average of all active channels.
4. Specification applies only to the tri-mode charge pump.
5. Specification applies only to the charge pump doubler.
4
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Typical Characteristics–Flash Driver Charge Pump Section
Maximum Current Pulse vs. Supply Voltage
(VOUT_FL = 4.5V; EN_FL = VIN; EN/SET = GND)
Output Voltage (V)
4.60
4.56
4.52
3.6V
4.48
3.0V
3.3V
4.44
2.7V
4.40
0.1
1.0
10.0
100.0
1000
Maximum Current Pulse (mA)
Output Voltage vs. Output Current
(VOUT_FL = 4.5V; EN_FL = VIN; EN/SET = GND)
450
400
One-shot pulse duration = 250ms
VOUT > 4.0V
350
300
250
200
150
100
50
0
3.0
3.1
Output Current (mA)
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
4.0
4.1
4.2
Supply Voltage (V)
Start-Up Time
Start-Up Time
(50mA Load)
(100mA Load)
EN_FLSH
(1V/div)
EN_FLSH
(1V/div)
VOUT_FL
(1V/div)
VOUT_FL
(1V/div)
100µ
µs/div
100µ
µs/div
Load Response vs. Time
Load Response vs. Time
(50mA Load)
(100mA Load)
VIN = 3.5V
VIN = 3.5V
VOUT_FL
(10mV/div)
VOUT_FL
(10mV/div)
IOUT
(20mA/div)
IOUT
(50mA/div)
5ms/div
5ms/div
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
5
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Typical Characteristics–Flash Driver Charge Pump Section
Output Ripple Voltage vs. Time
Output Ripple Voltage vs. Time
(IOUT = 50mA @ VIN = 3.5V)
(IOUT = 100mA @ VIN = 3.5V)
VIN
(10mV/div)
VIN
(10mV/div)
VOUT
(10mV/div)
VOUT
(20mV/div)
IIN
(10mA/div)
IIN
(10mA/div)
500ns/div
500ns/div
Supply Current vs. Supply Voltage
Oscillator Frequency vs. Supply Voltage
2.75
2.50
Oscillator Frequency (MHz)
Supply Current (mA)
3.00
IOUT = 0µA
C3 = 1µF
VEN_FL = VIN
2.25
2.00
1.75
1.50
1.25
1.00
2.5
3.0
3.5
4.0
Supply Voltage (V)
6
4.5
5.0
1.30
1.25
+25°C
1.20
1.15
+85°C
-40°C
1.10
2.7
3.2
3.7
4.2
Supply Voltage (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
4.7
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Typical Characteristics–White LED Backlight Driver Section
Unless otherwise noted, VIN = 3.6V, CIN = COUT = C1 = C2 = C3 = 1.0μF; TA = 25°C.
Turn-On to 1X Mode
Efficiency vs. Supply Voltage
100
4.1mA
VF = 2.9V
10.2mA
VF = 3.1V
(VIN = 4.2V; 20mA Load)
20mA
VF = 3.4V
EN
(2V/div)
Efficiency (%)
90
CP
(2V/div)
VSINK
(500mV/div)
80
70
IIN
(200mA/div)
60
50
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
100µ
µs/div
Supply Voltage (V)
Turn-On to 1.5X Mode
Turn-On to 2X Mode
(VIN = 3.8V; 20mA Load)
(VIN = 2.8V; 20mA Load)
EN
(2V/div)
EN
(2V/div)
CP
(2V/div)
VSINK
(500mV/div)
CP
(2V/div)
VSINK
(500mV/div)
IIN
(200mA/div)
IIN
(200mA/div)
100µ
µs/div
100µ
µs/div
Turn-Off from 1.5X Mode
Current Matching vs. Temperature
(VIN = 3.5V; 20mA Load)
20.2
Channel 1
Channel 2
EN
(2V/div)
Current (mA)
20.0
VF
(1V/div)
IIN
(100mA/div)
19.8
Channel 5
19.6
Channel 3
19.4
Channel 4
Channel 6
19.2
-40
100µ
µs/div
-20
0
20
40
60
80
Temperature (°°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
7
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Typical Characteristics–White LED Backlight Driver Section
Unless otherwise noted, VIN = 3.6V, CIN = COUT = C1 = C2 = C3 = 1.0μF; TA = 25°C.
Load Characteristics
Load Characteristics
(VIN = 3.8V; 1.5X Mode; 15mA Load)
(VIN = 2.9V; 2X Mode; 15mA Load)
VIN
(40mV/div)
VIN
(40mV/div)
CP
(40mV/div)
CP
(40mV/div)
VSINK
(40mV/div)
VSINK
(40mV/div)
500ns/div
500ns/div
Load Characteristics
Load Characteristics
(VIN = 4.0V; 1.5X Mode; 20mA Load)
(VIN = 3.1V; 2X Mode; 20mA Load)
VIN
(40mV/div)
VIN
(40mV/div)
CP
(40mV/div)
CP
(40mV/div)
VSINK
(40mV/div)
VSINK
(40mV/div)
500ns/div
500ns/div
Load Characteristics
Load Characteristics
(VIN = 4.3V; 1.5X Mode; 30mA Load)
(VIN = 3.6V; 2X Mode; 30mA Load)
VIN
(40mV/div)
VIN
(40mV/div)
CP
(40mV/div)
CP
(40mV/div)
VSINK
(40mV/div)
VSINK
(40mV/div)
500ns/div
8
500ns/div
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Typical Characteristics–White LED Backlight Driver Section
Unless otherwise noted, VIN = 3.6V, CIN = COUT = C1 = C2 = C3 = 1.0μF; TA = 25°C.
TLAT vs. VIN
TOFF vs. VIN
350
400
350
300
-40°C
-40°C
300
TOFF (µ
µs)
TLAT (µ
µs)
250
200
150
25°C
85°C
100
250
200
25°C
150
85°C
100
50
50
0
0
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
VIN (V)
VIN (V)
Input Ripple vs. VIN
VIH vs. VIN
1.2
25
1
-40°C
0.9
15
10
VIH (V)
Amplitude (mV)
1.1
30mA
20
20mA
0.7
25°C
0.6
85°C
0.5
10.2mA
5
0.8
0.4
0.3
0.2
0
2.50
2.67
2.84
3.01
3.18
3.35
3.52
3.69
3.86
4.03
4.2
VIN (V)
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
VIN (V)
VIL vs. VIN
1.2
1.1
1
VIL (V)
0.9
-40°C
0.8
0.7
0.6
0.5
25°C
85°C
0.4
0.3
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
VIN (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
9
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Functional Block Diagram
C1+
C1-
Soft-Start
2X
Charge Pump
EN_FL
1MHz
Oscillator
VOUT_FL
VIN
VREF
Soft-Start
Control
1MHz
Oscillator
C2 +
1X
1.5X
2X
Charge
Pump
C2 C3 +
C3 -
Voltage
Reference
6 x 16 bit
ROM
EN/SET
AS 2Cwire
Interface
6 x 16 bit
ROM
VOUT_BL
D/A
D1
D/A
D2
D/A
D3
D/A
D4
D/A
D5
D/A
D6
GND
Functional Description
The AAT2803 is a dual charge pump targeted for backlight and flash applications. The charge pump for white
LED applications is a tri-mode load switch (1X) and high
efficiency (1.5X or 2X) charge pump device. To maximize
power conversion efficiency, an internal sensing circuit
monitors the voltage required on each constant current
sink input and sets the load switch and charge pump
modes based on the input battery voltage and the current sink input voltage. As the battery discharges over
time, the backlight charge pump is enabled when any of
the six current sink inputs near dropout. The charge
pump initially starts in 1.5X mode. If the charge pump
output drops enough for any current source output to
become close to dropout, the charge pump will automatically transition to 2X mode.
For flash applications, charge pump doubler architecture
is used to support the high current demand required by
the application. Charge pump regulation is achieved by
sensing the output voltage through an internal resistor
10
divider network. A switch doubling circuit is enabled
when the divided output drops below a preset trip point
controlled by an internal comparator. The free-running
charge pump switching frequency is approximately
1MHz. The charge pump is designed to deliver 120mA of
continuous current and 300mA of pulsed current.
The AAT2803 requires only six external components:
three 1μF ceramic capacitors for the charge pump flying
capacitors (C1, C2, and C3), one 1μF ceramic input capacitor (CIN), one 0.33μF to 1μF ceramic capacitor for the
backlight charge pump output, and one 1μF for the flash
charge pump output. The six constant current sink
inputs (D1 to D6) can drive six individual LEDs with a
maximum current of 30mA each. The unused sink inputs
must be connected to VOUT_BL, otherwise the part will
operate only in 2X charge pump mode. The AS2Cwire
serial interface enables the backlight charge pump and
sets the current sink magnitudes. AS2Cwire addressing
allows independent control of two groups of current sink
input: D1 to D4 and D5 to D6.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Constant Current Output Level Settings
The constant current sink levels for the white LED backlight (D1 to D6) are set via the serial interface according
to a logarithmic scale where each code is 1dB lower than
the previous code. In this manner, LED brightness
appears linear with each increasing code count. Because
the inputs D1 to D6 are true independent constant current sinks, the voltage observed on any single given
input will be determined by the actual forward voltage
(VF) for the LED being driven.
Since the input current sinks are programmable, no PWM
(pulse width modulation) or additional control circuitry is
needed to control LED brightness. This feature greatly
reduces the burden on a microcontroller or system IC to
manage LED or display brightness, allowing the user to
“set it and forget it.” With its high-speed serial interface
(1MHz data rate), the input sink current can be changed
successively to brighten or dim LEDs in smooth transitions (e.g., to fade-out) or in abrupt steps, giving the
user complete programmability and real-time control of
LED brightness.
Data
30mA Max
IOUT (mA)
20mA Max
IOUT (mA)
15mA Max
IOUT (mA)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
30.0
26.7
23.8
21.4
19.0
16.7
15.2
13.3
11.9
10.5
9.5
8.6
7.6
6.7
6.2
0.0
20.0
17.8
15.9
14.3
12.7
11.1
10.2
8.9
7.9
7.0
6.3
5.7
5.1
4.4
4.1
0.0
15.0
13.3
11.9
10.7
9.5
8.3
7.6
6.7
6.0
5.2
4.8
4.3
3.8
3.3
3.1
0.0
The 16 individual current level settings are each approximately 1dB apart (see Current Level Settings table). Code
1 is full scale, Code 15 is full scale attenuated by 14dB,
and Code 16 is reserved as a “no current” setting.
AS2Cwire Serial Interface
The Advanced Simple Serial Control (AS2Cwire) single
wire interface is used to set the possible combinations of
current levels and LED channel states. AS2Cwire has
addressing capability for multiple data registers. With
multiple data registers, the backlight charge pump main
and sub-channels can be programmed together or independently from one another.
AS2Cwire relies on the number of rising edges of the EN/
SET pin to address and load the registers. AS2Cwire
latches data or address after the EN/SET pin has been
held high for time TLAT. 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 1 is signified by 17
rising edges, Address 2 by 18 rising edges, and so forth.
Data is set to any number of rising edges between 1 and
including 16. A typical write protocol is a burst of EN/SET
rising edges, signifying a particular Address, followed by
a pause with EN/SET held high for the TLAT timeout period, a burst of rising edges signifying Data, and a TLAT
timeout for the data registers. Once an address is set,
then multiple writes to the corresponding data register
are allowed.
When EN/SET is held low for an amount of time greater
than TOFF, the backlight charge pump enters into shutdown
mode and draws less than 1μA from the supply. Address
1 is the default address on the first rising edge after the
backlight charge pump has been disabled. Whenever
shutdown mode is entered, all registers are reset to 1.
Table 1: Current Level Settings.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
11
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
AS2Cwire Serial Interface Timing
Address
Data
T HI
T LO
TLAT
TLAT
EN/SET
1
Address
2
17
18
1
1
2...
n <= 16
2
Data Reg 1
1
Data Reg 2
1
n
AS2Cwire Addressing
Max Current and Low Current Registers
Five addresses are available to enable all of the part’s
functionality. Two 4-bit registers control the main and
sub-channels, giving 16 settings for each. The main and
sub-channels are programmed to the same constant current level by using Address 1. Use Addresses 2 and 3 to
program the main and sub-channels independently. Use
Address 4 to program the Max Current register, which
sets the Max Current scale. Lastly, Address 5 programs
the Low Current register. The Low Current register controls the efficient Low Current mode. When the Max
Current register is programmed to 1, 2, or 3, changing
the data for Addresses 1-3 will result in the corresponding values found in the Constant Current Programming
Levels table.
Use the Max Current and Low Current registers to program constant current settings outside of the 20mA Max
scale. By default (without changing the Max Current register), the backlight charge pump operates in the 20mA
Max scale (see Constant Current Programming Levels).
For example, to change to the 30mA Max scale, address
the Max Current register with 20 rising edges and pause
for TLAT. Program the Max Current register with 2 rising
edges and pause for TLAT. The part will next operate in
the same Data row, but for the setting found in the
30mA Max column. Next, to change to a different setting
on the 30mA Max scale, address the D1-D6 register with
17 rising edges. Program the new constant current level
with 1-16 rising edges. The part will update to the new
Data setting according to the Constant Current
Programming Levels table.
When the Max Current register is programmed to 4, the
part is programmed to operate in Low Current mode and
the Data for Addresses 1-3 is irrelevant. In Low Current
mode, the Low Current register takes precedence. See
the Low Current Register Settings table below for the
current level settings and main/sub-configurations that
result.
Address
EN/SET Edges
Addressed Register
1
2
3
4
5
17
18
19
20
21
1&2: D1-D6 Current
1: D1-D4 Current
2: D5-D6 Current
3: Max Current
4: Low Current
Table 2: Low Current Register Settings.
12
The backlight charge pump has a distinct Low Current
mode with ultra-low quiescent current. For drive currents
of 2mA or less, the part operates with significantly
reduced quiescent current. This is particularly useful for
applications requiring an “always on” condition such as
transmissive displays. As an example, to change to Low
Current mode, address the Max Current register with 20
rising edges and pause for TLAT. Program the Max Current
register with 4 rising edges and pause for TLAT. Address
the Low Current register with 21 rising edges and pause
for TLAT. Program the Low Current register with 1-16 rising edges. The part will update to the new Low Current
mode setting and operate with significantly reduced quiescent current.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Applications Information
Data
Max Current
1
2
3
4
20mA Max Scale
30mA Max Scale
15mA Max Scale
Low Current Mode
Table 3: Max Current Register Settings—Address 4.
Data
D1-D4 (mA)
D5-D6 (mA)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0
0
0
0
0
0
0
0
0.05
0.5
1
2
0.05
0.5
1
2
0
0
0
0
0.05
0.5
1
2
0
0
0
0
0.05
0.5
1
2
Table 4: Low Current Register Settings—Address 5.
Disabled Current Sinks
The backlight charge pump is equipped with an autodisable feature to protect against an LED failure condition. Current sink inputs that are not used should be
disabled. To disable and properly terminate unused current sink inputs, they must be tied to VOUT. If left unconnected or terminated to ground, the part will be forced
to operate in 2X charge pump mode.
Properly terminating unused current sink inputs is
important to prevent the charge pump modes from activating prematurely. When properly terminated, only a
small sense current flows for each disabled channel. The
sense current for each disabled channel is less than
120μA.
LED Selection
Although the AAT2803 is specifically intended for driving
white LEDs, the device can also be used to drive most
types of LEDs with forward voltage specifications ranging
from 2.0V to 4.7V. LED applications may include main
and sub-LCD display backlighting, camera photo-flash
applications, color (RGB) LEDs, infrared (IR) diodes for
remotes, and other loads benefiting from a controlled
output current generated from a varying input voltage.
In some instances (e.g., in high-luminous-output applications such as photo flash), it may be necessary to
drive high-VF type LEDs. The low-dropout current sinks
in the AAT2803 make it capable of driving LEDs with
forward voltages as high as 4.7V at full current from an
input supply as low as 3.0V. Outputs can be paralleled to
drive high-current LEDs without complication.
Device Switching Noise Performance
The AAT2803 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 AAT2803 soft-start feature prevents noise
transient effects associated with inrush currents during
start-up of the charge pump circuit.
Capacitor Selection
Careful selection of the six external capacitors CIN, C1,
C2, C3, and COUT (for backlight and flash) is important
because they will affect turn-on time, output ripple, and
transient performance. Optimum performance will be
obtained when low equivalent series resistance (ESR)
ceramic capacitors are used. In general, low ESR may be
defined as less than 100m. A value of 1μF for all four
capacitors is a good starting point when choosing capacitors. If the LED current sources are only programmed
for light current levels, then the capacitor size may be
decreased.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
13
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Capacitor Characteristics
Ceramic Capacitor Materials
Ceramic composition capacitors are highly recommended
over all other types of capacitors for use with the
AAT2803. Ceramic capacitors offer many advantages
over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically has very low ESR, is
lowest cost, has a smaller PCB footprint, and is nonpolarized. Low ESR ceramic capacitors help maximize
charge pump transient response. Since ceramic capacitors are non-polarized, they are not prone to incorrect
connection damage.
Ceramic capacitors less than 0.1μF are typically made
from NPO or C0G 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 not typically required.
Equivalent Series Resistance
ESR is an important characteristic to consider when
selecting a capacitor. ESR is a resistance internal to a
capacitor that is caused by the leads, internal connections, size or area, material composition, and ambient
temperature. Capacitor ESR is typically measured in milliohms for ceramic capacitors and can range to more
than several ohms for tantalum or aluminum electrolytic
capacitors.
14
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.
These larger devices can improve circuit transient
response when compared to an equal value capacitor in
a smaller package size.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
DATA SHEET
AAT2803
Six-Channel White LED Backlight Charge Pump with Flash
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
QFN44-24
OFXYY
AAT2803ISK-4.5-T1
Skyworks Green™ products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to Skyworks
Definition of Green™, document number
SQ04-0074.
Package Information3
QFN44-24
0.4 ± 0.05
24
1
2.7 ± 0.05
0.5 BSC
R0.030Max
13
6
12
4.000 ± 0.050
7
2.7 ± 0.05
Top View
0.025 ± 0.025
Bottom View
0.214 ± 0.036
0.900 ± 0.050
4.000 ± 0.050
19
18
0.300 × 45°
Pin 1 Identification
0.305 ± 0.075
Pin 1 Dot By Marking
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.
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a
service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no
responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes.
No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or information provided hereunder, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale.
THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR
PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. SKYWORKS DOES
NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, INCLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM
THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or environmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper
use or sale.
Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of products outside of published parameters or design specifications. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product
design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifications or parameters.
Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for
identification purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012
15