Data Sheets - Skyworks Solutions, Inc.

DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
General Description
Features
The AAT3159 is a low noise, constant frequency charge
pump DC/DC converter that uses a tri-mode load switch
(1X), fractional (1.5X), and doubling (2X) conversion to
maximize efficiency for white LED applications. The
device is capable of driving up to four channels of LEDs
at up to 40mA per channel from a 2.7V to 5.5V input
supply voltage. The current sinks may be operated individually or in parallel for driving higher-current LEDs. A
low external parts count (two 1µF flying capacitors [C1
and C2] and two small 1µF capacitors [CIN and COUT])
makes this part ideally suited for small battery-powered
applications.
• Input Supply Voltage Range: 2.7V to 5.5V
• Tri-Mode (1X/1.5X/2X) Charge Pump
• Maximizes Efficiency
• 1MHz Constant Switching Frequency
• No Inductors, Low Noise Operation
• Drives Four Channels of LEDs up to 40mA/ Channel
• User-Programmable LED Current
•
Excellent
LED
Channel-to-Channel
Current
Matching
• Digitally Programmable LED Current with Single-Wire
S2Cwire Interface
• 16 Current Levels From 40mA to 50µA
• Low IQ (50µA) for Low Current Mode Operation
• True Load Disconnect in Shutdown; IQ < 1µA
• Built-In Thermal Protection
• Built-In Auto-Disable for Open LED Circuit
• Automatic Soft-Start Minimizes Inrush Startup
Current
• 2.85x3x1mm TSOPJW-14 Package
Skyworks' patented single-wire Simple Serial Control
(S2Cwire™) serial digital interface is used to enable, disable, and set the current for each LED with 16 levels
from a maximum of 40mA down to 50µA. The maximum
current level is programmed via an external resistor. To
save power, low-current mode supply current will be as
low as 50µA.
Each output of the AAT3159 is equipped with built- in
protection for VOUT short-circuit operation and auto-disable functionality for LED open-circuit conditions. Built-in
soft-start circuitry prevents excessive inrush current
during start-up. A low-current shutdown feature disconnects the load from IN and reduces quiescent current to
less than 1µA.
Applications
•
•
•
•
Cellphones, DSC, Handheld Devices
LED Photo Flash
Programmable Current Sinks
White LED Backlighting
The AAT3159 is available in a Pb-free, space-saving
2.85x3x1mm TSOPJW-14 package.
Typical Application
C1
1µF
VBATTERY
3.6V
C1+
C2+
C1-
C2-
IN
OUT
AAT3159
CIN
1µF
C2
1µF
COUT
1µF
GND
WLEDs
OSRAM LW M67C
or equivalent
D1
D2
D3
D4
D1
EN/SET
S Cwire Serial Control
2
RSET
26.1kΩ
EN/SET
D2
SET
D3
D4
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
1
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Pin Descriptions
Pin #
Symbol
1
2
3
4
5
6
7
8
9, 11
10
12
13
14
D4
SET
EN/SET
C1+
C1OUT
C2+
C2GND
IN
D1
D2
D3
Function
Current sink input #4. Connect to the cathode of LED4. If not used, connect
LED current setting resistor input/connection.
S2Cwire serial interface control input for LED current magnitude control.
Positive terminal of charge pump capacitor 1.
Negative terminal of charge pump capacitor 1.
Charge pump output. Connect all LED anodes to OUT.
Positive terminal of charge pump capacitor 2.
Negative terminal of charge pump capacitor 2.
Ground.
Input power supply connection.
Current sink input #1. Connect to the cathode of LED1. If not used, connect
Current sink input #2. Connect to the cathode of LED2. If not used, connect
Current sink input #3. Connect to the cathode of LED3. If not used, connect
D4 to the OUT pin.
D1 to the OUT pin.
D2 to the OUT pin.
D3 to the OUT pin.
Pin Configuration
TSOPJW-14
(Top View)
D4
1
14
D3
SET
2
13
D2
EN/SET
3
12
D1
C1+
4
11
GND
C1-
5
10
IN
6
9
7
8
OUT
C2+
2
GND
C2-
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Absolute Maximum Ratings1
Symbol
VN
VN
VN
TJ
TLEAD
Description
[IN, OUT, D1, D2, D3, D4] to GND
[C1-, C2-, EN/SET, SET] to GND
[C1+, C2+] to GND
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
Units
-0.3 to 6
-0.3 to VIN + 0.3
-0.3 to VOUT + 0.3
-40 to 150
300
V
V
V
°C
°C
Value
Units
0.625
160
W
°C/W
Thermal Information2
Symbol
PD
qJA
Description
Maximum Power Dissipation3
Maximum Thermal Resistance
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions
specified is not implied. Only one Absolute Maximum Rating should be applied at any one time.
2. Mounted on a FR4 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
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
3
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Electrical Characteristics1
VIN = 3.6V; CIN = COUT = C1 = C2 = 1.0µF; TA = -40°C to +85°C, unless otherwise noted.
TA = 25°C.
Symbol
Description
Conditions
Input Power Supply
VIN
Input Supply Voltage Range
ICC
ISHDN
IDX
I(D-Match)
Operating Input Current
Shutdown Current
DX Pin Current
Current Matching
1X to 1.5X or 1.5X to 2X TranVTH
sition Threshold at Any DX Pin
ISET
Current Set Ratio
VSET
SET Pin Voltage
Charge Pump Section
TSS
Soft-Start Time
FCLK
Clock Frequency
EN/SET Logic Control
VIL(EN/SET)
Enable Logic Low Threshold
VIH(EN/SET)
Enable Logic High Threshold
TEN/SET LO
EN/SET Low Time
TEN/SET HI MIN Minimum EN/SET High Time
TEN/SET HI MAX Maximum EN/SET High Time
TOFF
EN/SET Off Timeout
TLAT
EN/SET Latch Timeout
IEN/SET
EN/SET Input Leakage
2
Min
Typical values are
Typ
Max
Units
5.5
1
3
V
mA
1
µA
µA
20
22
mA
0.5
1
%
2.7
1X Mode, 3.0 ≤ VIN ≤ 5.5, Active, No Load Current
1.5X Mode, 3.0 ≤ VIN ≤ 5.5, Active, No Load Current
2X Mode, 3.0 ≤ VIN ≤ 5.5, Active, No Load Current
50µA Setting, 1X Mode EN/SET = 0
TA= -40°C to +85°C, RSET = 26.1kW, Data = 1
(100%)
VF:D1:D4 = 3.6V
0.3
1
1
50
18
ISINK/IRSET
VIN = 2.7V
VIN = 5.5V
150
mV
870
0.6
A/A
V
100
1000
µs
kHz
0.4
1.4
0.3
75
50
-1
75
500
500
1
V
V
µs
ns
µs
µs
µs
µA
1. The AAT3159 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
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Typical Characteristics
VIN = 3.6V; CIN = COUT = C1 = C2 = 1.0µF; TA = -40°C to +85°C, unless otherwise noted.
TA = 25°C.
Efficiency vs. Input Voltage
100
Efficiency (%)
90
Turn-On to 1X Mode
(VIN = 4.2V; 20mA/Channel Load)
20mA/channel
VF = 3.4V
6mA/channel
VF = 3V
VEN/SET
(1V/div)
80
70
VOUT
(2V/div)
VDX
(1V/div)
IIN
(100mA/div)
60
50
500µA/channel
VF = 2.7V
40
30
2.7
2.9
3.1
3.3
3.5
3.7
Typical values are
3.9
4.1
4.3
Input Voltage (V)
4.5
Time (100µs/div)
Turn-On to 1.5X Mode
Turn-On to 2X Mode
(VIN = 3.5V; 20mA/Channel Load)
(VIN = 2.8V; 20mA/Channel Load)
VEN/SET
(1V/div)
VEN/SET
(1V/div)
VOUT
(4V/div)
VOUT
(4V/div)
VDX
(1V/div)
IIN
(200mA/div)
VDX
(500mV/div)
IIN
(500mA/div)
Time (100µs/div)
Time (100µs/div)
LED Current vs. Temperature
Turn-Off from 1.5X Mode
(20mA/Channel)
(VIN = 3.5V; 20mA/Channel Load)
22.0
21.5
LED Current (mA)
VEN/SET
(1V/div)
VF
(4V/div)
IIN
(100mA/div)
21.0
20.5
ID4
ID2
19.5
19.0
ID3
18.5
18.0
-40
Time (100µs/div)
ID1
20.0
-15
10
35
60
85
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
5
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Typical Characteristics
VIN = 3.6V; CIN = COUT = C1 = C2 = 1.0µF; TA = -40°C to +85°C, unless otherwise noted.
TA = 25°C.
Operating Characteristics
Typical values are
Operating Characteristics
(VIN = 3.7V; 1.5X Mode;
20mA/Channel Load; AC Coupled)
(VIN = 3.5V; 1.5X Mode;
14mA/Channel Load; AC Coupled)
VIN
(20mV/div)
VIN
(20mV/div)
VOUT
(40mV/div)
VOUT
(40mV/div)
VDX
(20mV/div)
VDX
(20mV/div)
Time (500ns/div)
Time (500ns/div)
Operating Characteristics
Operating Characteristics
(VIN = 2.9V; 2X Mode;
20mA/Channel Load; AC Coupled)
(VIN = 2.9V; 2X Mode;
14mA/Channel Load; AC Coupled)
VIN
(20mV/div)
VIN
(20mV/div)
VOUT
(40mV/div)
VOUT
(40mV/div)
VDX
(40mV/div)
VDX
(40mV/div)
Time (500ns/div)
Time (500ns/div)
Input Ripple vs. Input Voltage
14.0
20mA/channel
Input Ripple (mV)
12.0
10.0
14mA/channel
8.0
6.0
4.0
10mA/
channel
2.0
0.0
2.7
3.1
3.5
3.9
4.3
Input Voltage (V)
6
4.7
5.1
5.5
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Typical Characteristics
VIN = 3.6V; CIN = COUT = C1 = C2 = 1.0µF; TA = -40°C to +85°C, unless otherwise noted.
TA = 25°C.
350
EN/SET Off Timeout (µs)
350
300
250
200
-40°C
150
100
85°C
25°C
50
300
250
-40°C
200
150
25°C
100
85°C
50
0
0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
EN/SET Logic High Threshold (V)
EN/SET Off Timeout vs. Input Voltage
2.7
EN/SET High Threshold Voltage
vs. Input Voltage
1.4
1.2
-40°C
1.0
0.8
25°C
0.6
0.4
2.7
3.1
3.5
3.9
4.3
Input Voltage (V)
3.1
3.5
85°C
4.7
5.1
5.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
EN/SET Logic Low Threshold (V)
EN/SET Latch Timeout (µs)
EN/SET Latch Timeout vs. Input Voltage
Typical values are
EN/SET Low Threshold Voltage
vs. Input Voltage
1.4
1.2
1.0
-40°C
0.8
0.6
25°C
85°C
0.4
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
7
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Functional Block Diagram
C1+
C1- C2+ C2-
1x, 1.5x and 2x
Charge Pump
IN
OUT
Soft Start
Control
1MHz
Oscillator
Voltage
Reference
EN/SET
S2Cwire
Interface
6x16 bit
ROM
D/A
D1
D/A
D2
D/A
D3
D/A
D4
Max Current
Adjustment
GND (2)
Functional Description
The AAT3159 is a tri-mode load switch (1X) and high
efficiency (1.5X or 2X) charge pump device intended for
white LED backlight applications. 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
AAT3159 charge pump is enabled when any of the four
current sink inputs nears dropout. The charge pump
initially starts in 1.5X mode. If the charge pump output
droops enough for any current source output to become
close to dropout, the charge pump will automatically
transition to 2X mode. The AAT3159 requires only four
external components: two 1µF ceramic capacitors for
the charge pump flying capacitors (C1 and C2), one 1µF
8
SET
ceramic input capacitor (CIN), and one 0.33µF to 1µF
ceramic output capacitor (COUT).
The four constant current sink inputs (D1 to D4) can
drive four individual LEDs with a maximum current of
40mA each. The unused sink inputs must be connected
to VOUT; otherwise, the part will operate only in 2X
charge pump mode. The S2Cwire serial interface enables
the AAT3159 and sets the LED current magnitudes.
Constant Current Output Level Settings
The LED current magnitude is controlled by Skyworks'
S2Cwire serial digital interface. The maximum current is
programmed by an external resistor at the SET pin.
Since the current sinks are programmable, no PWM
(pulse width modulation) or additional control circuitry is
needed to control LED brightness. This feature greatly
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
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 LED 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. The code settings for the AAT3159 are listed
in Table 1.
The S2Cwire serial interface has flexible timing. Data can
be clocked-in at speeds greater than 1MHz, or much
slower, such as 15kHz. After data is submitted, EN/SET
is held high to latch the data. Once EN/SET has been held
in the logic high state longer than TLAT (500µs), the programmed current becomes active. For subsequent current level programming, the number of rising edges corresponding to the desired code must be entered on the
EN/SET pin.
When EN/SET is held logic low longer than TOFF (500µs),
the AAT3159 enters into shutdown mode and draws less
than 1µA from IN. The internal data register is reset to
zero during shutdown.
S2Cwire Serial Interface
The current level magnitude is controlled by Skyworks'
Simple Serial Control (S2Cwire) serial interface. The
interface records rising edges of the EN/SET pin and
decodes them into 16 different states. The 16 current
level settings available are indicated in Table 1.
Data
All LED Outputs D1 - D4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
100%
90%
79%
70%
62%
55%
48%
40%
31%
21%
15%
11%
1mA
500µA
100µA
50µA
Auto-Disable Feature
The AAT3159 is equipped with an auto-disable feature
for each LED channel. After the IC is enabled and started
up, a test current of 100µA (typical) is forced through
each sink channel. The channel will be disabled if the
voltage of that particular current sink (DX pin) does not
drop to a specific threshold. This feature is very convenient for disabling an unused channel or during an LED
fail short event.
Thermal Protection
The AAT3159 has built-in thermal protection circuit that
will shut down the charge pump if the die temperature
rises above the thermal limit, as is the case during a
short-circuit event with the OUT pin.
Table 1: AAT3159 LED Current Levels as a
Percentage of the Maximum Level Set by RSET.
S2Cwire Serial Interface Timing
T HI
T LO
TOFF
TLAT
EN/SET
1
Data Reg
2
n
1
n <= 16
n
0
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
9
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Maximum LED Current vs. RSET
Applications Information
45
40
LED Selection
35
Determining the Maximum LED Current
Level
The value of RSET determines the maximum LED current
level. In the typical application, selecting RSET = 26.1kW
results in 20mA/channel LED current. From this reference point, the RSET value required for other current
levels can be calculated as:
RSET =
20mA · 26.1kΩ
ILED(MAX)
A visual representation of the maximum LED current per
channel versus RSET value is shown in Figure 1. Since the
AAT3159’s LED current control circuits were optimzed for
full-scale current settings higher than 15mA, RSET values
smaller than or equal to 33.2kW are recommended.
Brightness Control Using the SET Pin
Additional methods of brightness control can be achieved
with the SET pin. For example, using an additional resistor to connect the SET pin with a digital output provides
a HI/LO control. Figure 2 illustrates a configuration of
the SET pin utilizing two resistors.
10
30
ID (mA)
Although the AAT3159 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 photoflash applications, color (RGB) LEDs, infrared (IR) diodes
for remotes, and other loads benefiting from a controlled output current generated from a varying input
voltage. Since the D1 to D4 input current sinks are
matched with negligible voltage dependence, the LED
brightness will be matched regardless of the specific LED
forward voltage (VF) levels. 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 AAT3159 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.
25
20
15
10
5
0
10
15
20
25
30
35
40
45
50
55
60
65
70
75
RSET (kΩ)
Figure 1: Maximum LED Current vs. RSET.
AAT3159
HI/LO
or
VDAC
R2
SET
R1
Figure 2: SET Pin Configuration Using
Two Resistors.
When the digital output is asserted high, the resulting
brightness level is LO and the individual LED currents
are:
 0.6V
VIO
ILED(LO) = ISET  R // R - R 
1
2
2
When the digital output is asserted low, the resulting
brightness level is HI and the individual LED currents
are:
 0.6V 
ILED(HI) = ISET  R // R 
1
2
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Additionally, a digital-to-analog converter can be used
with the SET pin to control the brightness level. The
result is like the equation above, where VIO is replaced
with VDAC:
 0.6V
VDAC
ILED(LO) = ISET  R // R - R 
1
2
2
For cases where PWM dimming is preferred, the PWM
signal can be applied directly to the SET resistor, as
shown in Figure 3. In order for the LED current to go to
zero, the voltage level of the PWM signal must be higher
than the SET pin voltage of 0.6V.
AAT3159
PWM
R1
SET
η=
4 · VLEDX · ILEDX
; x = 1, 2, 3 or 4 and IIN = 4 · ILEDX
VIN · IIN
VLEDX
η= V
IN
Due to the very low 1X mode quiescent current, the
input current nearly equals the total output current
delivered to the LEDs. Further, the low resistance bypass
switch introduces a negligible voltage drop from input to
output.
The AAT3159 further maintains optimized performance
and efficiency by detecting when the input voltage is not
sufficient to sustain the LED bias current. The device automatically switches to 1.5X mode when the input voltage
drops too low in relation to the LED forward voltages.
In 1.5X mode, the output voltage can be boosted to 1.5X
the input voltage. The 1.5X conversion ratio introduces a
corresponding 0.5X increase in input current. For ideal
conversion, the 1.5X mode efficiency is given by:
η=
Figure 3: SET Pin Configuration for
PWM Dimming Control.
Device Power Efficiency
The AAT3159’s power conversion efficiency depends on
the charge pump mode of operation. By definition,
device efficiency is expressed as the output power delivered to the LEDs divided by the total input power
consumed.
η=
PLEDs VLED1 · ILED1 + ... + VLED4 · ILED4
=
PIN
VIN · IIN
When the input voltage is sufficiently greater than the
LED forward voltages, the device optimizes efficiency by
operating in 1X mode. In 1X mode, the device is working
as a bypass switch and passing the input supply directly
to the output. By simplifying the conditions such that the
LEDs have uniform VF, the power conversion efficiency
can be approximated by:
η=
η=
PLEDs VLED1 · ILED1 + ... + VLED4 · ILED4
=
PIN
VIN · IIN
4 · VLEDX · ILEDX
; x = 1, 2, 3 or 4 and IIN = 1.5(4 · ILEDX)
VIN · IIN
VLEDX
η = 1.5V
IN
Similarly, when the input falls further, such that 1.5X
mode can no longer sustain the LED bias currents, the
AAT3159 will automatically switch to 2X mode. In 2X
mode, the output voltage can be boosted to 2X the input
voltage. The 2X conversion ratio introduces a corresponding 1X increase in input current. For ideal conversion, the 2X mode efficiency is given by:
η=
η=
PLEDs VLED1 · ILED1 + ... + VLED4 · ILED4
=
PIN
VIN · IIN
4 · VLEDX · ILEDX
; x = 1, 2, 3 or 4 and IIN = 2(4 · ILEDX)
VIN · IIN
VLEDX
η = 2V
IN
PLEDs VLED1 · ILED1 + ... + VLED4 · ILED4
=
PIN
VIN · IIN
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
11
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Device Switching Noise Performance
Equivalent Series Resistance
The AAT3159 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 AAT3159 soft-start feature prevents noise
transient effects associated with inrush currents during
start-up of the charge pump circuit.
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.
Capacitor Selection
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 typically not required
for AAT3159 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. These larger devices can
improve circuit transient response when compared to an
equal value capacitor in a smaller package size.
Careful selection of the four external capacitors (CIN, C1,
C2, COUT) is important because they will affect turn-on
time, output ripple, and transient performance. Optimum
performance will be obtained when low Equivalent Series
Resistance (ESR) ceramic capacitors are used; in general, low ESR may be defined as less than 100mW. 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.
Capacitor Characteristics
Ceramic composition capacitors are highly recommended over all other types of capacitors for use with the
AAT3159. 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.
12
Ceramic Capacitor Materials
PCB Layout
To achieve adequate electrical and thermal performance,
careful attention must be given to the printed circuit
board (PCB) layout of the AAT3159. Figures 5 and 6
illustrate an example PCB layout for the AAT3159 (evaluation board). The flying capacitors (C1 and C2), input
capacitor (C4), and output capacitor (C3) should be connected as close as possible to the IC. In addition to the
external passive components being placed as close as
possible to the IC, all traces connecting the AAT3159
should be as short and wide as possible to minimize path
resistance and potential coupling.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Evaluation Board Schematic
DC-
TP3
GND
DC+
TP1
TP4
GND
TP2
DC-
DC+
GND
ON OFF
GND
J1
VIN
JP6
R1
24.9K
C1
1µF
GND
C3
1µF
JP5
1
2
3
4
5
6
7
U1
D4
SET
EN/SET
C1+
C1VOUT
C2+
D3
D2
D1
GND
VIN
GND
C2-
14
13
12
11
10
9
8
C4
1µF
AAT3159
C2
1µF
GND
GND
JP1
JP2
JP3
JP4
D1
WHITE
D2
WHITE
D3
WHITE
D4
WHITE
R8
220Ω
ON OFF
J2
R7
100K
GND
VIN
R4
1K
CYCLE
SW3
UP
SW2
DOWN
SW1
R3
1K
R2
1K
1
2
3
4
U2
VDD
GP5
GP4
GP3
PIC12F675
VR1
10K-POT
8
VSS
7
GP0
6
GP1
5
GP2
R5
330Ω
C5
1µF
GND
R6
330Ω
LED7
RED
GND
LED0
GREEN
GND
GND
Figure 4: AAT3159 Evaluation Board Schematic.
Evaluation Board Layout
Figure 5: AAT3159 Evaluation Board Top Side Layout.
Figure 6: AAT3159 Evaluation Board
Bottom Side Layout.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
13
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TSOPJW-14
TLXYY
AAT3159ITO-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 Information
TSOPJW-14
2.85 ± 0.20
2.40 ± 0.10
0.20 +- 0.10
0.05
0.40 BSC
Top View
0.04 REF
0.05 +- 0.05
0.04
Side View
0.15 ± 0.05
+ 0.05
1.05 - 0.00
+ 0.000
1.00 - 0.075
3.05 +- 0.05
0.10
4° ± 4°
0.45 ± 0.15
2.75 ± 0.25
End View
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
14
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
DATA SHEET
AAT3159
AAT3159 High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
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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
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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202154A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 11, 2012
15