Analogic AAT3143ITP-T1 High efficiency 1x/1.5x/2x charge pump with pwm control for white led application Datasheet

AAT3143
High Efficiency 1X/1.5X/2X Charge Pump with
PWM Control for White LED Applications
ChargePump™
General Description
Features
The AAT3143 is a low noise, constant frequency
charge pump DC/DC converter that uses a trimode load switch (1X), fractional (1.5X), and doubling (2X) conversion to maximize efficiency for
white LED applications. The AAT3143 can deliver
current levels up to 80mA to drive white LEDs connected to the four current source outputs from a
2.7V to 5.5V input. The current source outputs may
source up to 20mA each and may be operated individually or in parallel for driving higher-current
LEDs. A low external parts count (two 1µF flying
capacitors and two small 1µF capacitors at VIN and
VOUT) makes the AAT3143 ideally suited for small
battery-powered applications.
•
•
•
Output current, and therefore brightness, is controlled via externally applied Pulse Width Modulation
(PWM) control. Typically, PWM frequencies of up to
50kHz can be applied.
Applications
•
•
•
•
•
•
•
•
•
•
•
The AAT3143 has a thermal management system to
protect the device in the event of a short-circuit condition at the voltage output pin. Built-in soft-start circuitry prevents excessive inrush current during startup. A high charge pump switching frequency allows
the use of very small external capacitors. A low current shutdown feature disconnects the load from VIN
and reduces quiescent current to less than 1µA.
Input Voltage Range: 2.7V to 5.5V
PWM Brightness Control
Tri-Mode 1X, 1.5X, and 2X Charge Pump for
Maximum Efficiency and VF Coverage
Drives Four Low- or High-VF Type LEDs
Up to 20mA LED Current per Channel
No Inductors
1MHz Switching Frequency
Small Application Circuit
AutoBias™ Technology
IQ <1µA in Shutdown
2.85x3.0mm TSOPJW-12 Package
Programmable Current Sources
White LED Backlighting
White Photo Flash for Digital Still Cameras
The AAT3143 is available in a Pb-free, space-saving, 2.85x3.0mm 12-pin TSOPJW package.
Typical Application
IN
2.7V to 5.5V
C1+
CIN
1µF
C1
1µF
C1C2+
AAT3143
C2
1µF
C2CP
COUT
1µF
D1
PWM/EN
D2
EN/PWM
D3
D4
GND
3143.2006.05.1.0
D4
D3
D2
D1
1
AAT3143
High Efficiency 1X/1.5X/2X Charge Pump with
PWM Control for White LED Applications
Pin Descriptions
Pin #
Symbol
Function
1
2
3
4
5
6
7
8
9
10
11
12
C2+
CP
C1C1+
D3
D2
D4
D1
EN/PWM
IN
GND
C2-
Flying capacitor 2 positive terminal. Connect a 1µF capacitor between C2+ and C2-.
Charge pump output. Requires 1µF capacitor connected between this pin and ground.
Flying capacitor 1 negative terminal.
Flying capacitor 1 positive terminal. Connect a 1µF capacitor between C1+ and C1-.
Current source output #3.
Current source output #2.
Current source output #4.
Current source output #1.
Enable/PWM control pin.
Input power supply. Requires 1µF capacitor connected between this pin and ground.
Ground.
Flying capacitor 2 negative terminal.
Pin Configuration
TSOPJW-12
(Top View)
C2+
CP
C1C1+
D3
D2
2
1
12
2
11
3
10
4
9
5
8
6
7
C2GND
IN
EN/PWM
D1
D4
3143.2006.05.1.0
AAT3143
High Efficiency 1X/1.5X/2X Charge Pump with
PWM Control for White LED Applications
Absolute Maximum Ratings1
Symbol
Description
VIN
VEN/PWM
IOUT2
TJ
TLEAD
Input Voltage
EN/PWM to GND Voltage
Maximum DC Output Current
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
Units
-0.3 to 6
-0.3 to VIN + 0.3
80
-40 to 150
300
V
V
mA
°C
°C
Value
Units
0.625
160
W
°C/W
Thermal Information3
Symbol
PD
θJA
Description
Maximum Power Dissipation
Maximum Thermal Resistance
4
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. Based on long-term current density limitation.
3. Mounted on an FR4 board.
4. Derate 6.25 mW/°C above 25°C.
3143.2006.05.1.0
3
AAT3143
High Efficiency 1X/1.5X/2X Charge Pump with
PWM Control for White LED Applications
Electrical Characteristics1
CIN = CCP = C1 = C2 = 1.0µF; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C,
VIN = 3.5V.
Symbol
Description
Conditions
Input Power Supply
VIN
Operation Range
ICC
ISHDN
IDX
Operating Current
I(D-Match)
Shutdown Current
Output Current Accuracy
Current Matching2
ηCP
Charge Pump Efficiency
Charge Pump
FCLK
EN/PWM
VEN(L)
VEN(H)
FPWM
tON(MIN)
Min
2.7
VD1:D4 = 2.0V, CP = 1X
No Load Current, CP = 1.5X
EN/PWM = 0
IOUT = 20mA, TA = 25°C, VIN = 3.5V
VD1:D4 = 3.6V, VIN = 3.5V
VIN = 3.5V, IOUT(TOTAL) = 80mA,
Measured from IN to CP
550
3
18
-3
Section
Clock Frequency
Enable Threshold Low
Enable Threshold High
Maximum PWM Frequency
Minimum Pulse Width
Typ
20
±0.5
Max
Units
5.5
V
5
1
22
3
µA
µA
mA
%
93
%
1000
kHz
0.4
1.4
50
2
V
V
kHz
µs
1. The AAT3143 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 I(D-Match) = (ID - IAVE)/IAVE.
4
3143.2006.05.1.0
AAT3143
High Efficiency 1X/1.5X/2X Charge Pump with
PWM Control for White LED Applications
Typical Characteristics
VIN = 3.5V, CIN = CCP = C1 = C2 = 1µF, TA = 25°C, unless otherwise noted.
Efficiency
Turn-On to 1X Mode
(100% Duty Cycle, 4x20mA/channel)
(VIN = 4.2V)
100
VEN
(1V/div)
Efficiency (%)
90
80
VCP
(2V/div)
70
60
VLED
(2V/div)
50
40
30
2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2
IIN
(100mA/div)
Input Voltage (V)
Time (50µs/div)
Turn-On to 1.5X Mode
Turn-On to 2X Mode
(VIN = 3.5V)
(VIN = 2.7V)
VEN
(1V/div)
VEN
(1V/div)
VCP
(2V/div)
VCP
(2V/div)
VLED
(2V/div)
VLED
(2V/div)
IIN
(50mA/div)
IIN
(50mA/div)
Time (50µs/div)
Time (50µs/div)
LED Turn-On Delay
LED Turn-On Delay
(PWM Frequency = 500Hz)
(PWM Frequency = 5kHz)
VEN
(2V/div)
VEN
(2V/div)
VLED
(2V/div)
VLED
(2V/div)
ILED
(10mA/div)
ILED
(10mA/div)
Time (5µs/div)
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Time (1µs/div)
5
AAT3143
High Efficiency 1X/1.5X/2X Charge Pump with
PWM Control for White LED Applications
Typical Characteristics
VIN = 3.5V, CIN = CCP = C1 = C2 = 1µF, TA = 25°C, unless otherwise noted.
1.5X Mode PWM Characteristic
PWM Duty Cycle vs. LED Current
(5kHz at 50% Duty Cycle)
20
VEN
(2V/div)
LED Current (mA)
18
ILED
(20mA/div)
IIN
(100mA/div)
100Hz
1kHz
16
14
12
10kHz
10
8
6
4
2
VLED
(2V/div)
0
0
10
20
30
40
50
60
70
80
90
100
Duty Cycle (%)
Time (50µs/div)
Line Response
Line Response
(1X Mode, 4x19mA Load)
(1.5X Mode, 4x19mA Load)
VIN
(0.5V/div)
VIN
(0.5V/div)
VLED
(20mV/div)
VLED
(20mV/div)
VCP
(0.5V/div)
VCP
(0.5V/div)
ID
(10mA/div)
ID
(10mA/div)
Time (1ms/div)
Time (1ms/div)
Input Current vs. Input Voltage
Load Characteristics
(4x10mA)
(1.5X Mode, 4x15mA Load)
90
80
Input Current (mA)
VF
(20mV/div)
IIN
(10mA/div)
VCP
(20mV/div)
VDIODE = 3.4V
70
60
50
40
30
20
VDIODE = 3.0V
10
0
2.7
TIme (1µs/div)
6
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
3143.2006.05.1.0
AAT3143
High Efficiency 1X/1.5X/2X Charge Pump with
PWM Control for White LED Applications
Typical Characteristics
VIN = 3.5V, CIN = CCP = C1 = C2 = 1µF, TA = 25°C, unless otherwise noted.
VIH and VIL vs. VIN
0.850
0.825
0.800
0.775
VIH
0.750
0.725
VIL
0.700
0.675
0.650
0.625
0.600
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Input Voltage (V)
3143.2006.05.1.0
7
AAT3143
High Efficiency 1X/1.5X/2X Charge Pump with
PWM Control for White LED Applications
Functional Block Diagram
C1+
C1- C2+
C2-
1X/1.5X/2X
Charge Pump
IN
CP
Soft-Start
Control
1MHz
Oscillator
Voltage
Reference
EN/PWM
D/A
D1
D/A
D2
D/A
D3
D/A
D4
EN/PWM
GND
Functional Description
The AAT3143 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 source output and sets the
load switch and charge pump modes based on the
input battery voltage and the current source output
voltage. As the battery discharges over time, the
AAT3143 charge pump is enabled when any of the
four current source outputs nears dropout. The
charge pump initially starts in 1.5X mode. If the
charge pump output drops enough for any current
8
source output to become close to dropout, the
charge pump will automatically transition to 2X
mode. The AAT3143 requires only four external
components: two 1µF ceramic capacitors for the
charge pump flying capacitors (C1 and C2), one 1µF
ceramic input capacitor (CIN), and one 0.33µF to
1µF ceramic charge pump output capacitor (COUT).
The four constant current source outputs (D1 to
D4) can drive four individual LEDs with a maximum
current of 20mA each. The unused source outputs
must be connected to GND, otherwise the part will
operate only in 2X charge pump mode. The
EN/PWM input allows the user to control the brightness of the four LEDs by PWMing up to 50kHz.
3143.2006.05.1.0
AAT3143
High Efficiency 1X/1.5X/2X Charge Pump with
PWM Control for White LED Applications
Applications Information
EN/PWM Dimming Control
LED brightness is controlled with the EN/PWM pin.
By driving the pin with a PWM signal, a corresponding pulse-width modulated current will be driven
through the LEDs. In this way, the duty cycle sets
the LED brightness level. The resulting average
current that flows through the LED is calculated as
follows:
ILED = DC · 20mA
Capacitor Selection
Careful selection of the four external capacitors
CIN, C1, C2, and 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 100mΩ. 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 capacitor size may be decreased.
Capacitor Characteristics
The EN/PWM pin can be driven with a wide range
of PWM frequencies. Because of the short turn-on
delay during high frequency PWM, a frequency as
high as 50kHz can be used. A low PWM frequency
can also be used without complication. One should
consider that below 50Hz, the human eye can
begin to see LED flicker, so it is recommended that
users choose an adequate PWM frequency
exceeding 50Hz.
Ceramic composition capacitors are highly recommended over all other types of capacitors for use
with the AAT3143. 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 non-polarized. Low-ESR
ceramic capacitors help maximize charge pump
transient response. Since ceramic capacitors are
non-polarized, they are not prone to incorrect connection damage.
LED Selection
Although the AAT3143 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, 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 sources 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 sources in the AAT3143 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 highcurrent LEDs without complication.
3143.2006.05.1.0
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.
Ceramic Capacitor Materials
Ceramic capacitors less than 0.1µF are typically
made from NPO or C0G materials. NPO and C0G
materials generally have tight tolerance and are
very stable over temperature. Larger capacitor values are usually composed of X7R, X5R, Z5U, or
Y5V dielectric materials. Large ceramic capacitors
(i.e., greater than 2.2µF) are often available in lowcost Y5V and Z5U dielectrics, but capacitors
greater than 1µF are not typically required for
AAT3143 applications.
9
AAT3143
High Efficiency 1X/1.5X/2X Charge Pump with
PWM Control for White LED 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.
10
Thermal Protection
The AAT3143 has a 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 of the CP pin.
3143.2006.05.1.0
AAT3143
High Efficiency 1X/1.5X/2X Charge Pump with
PWM Control for White LED Applications
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TSOPJW-12
ROXYY
AAT3143ITP-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/pbfree.
Package Information
TSOPJW-12
2.85 ± 0.20
+ 0.10
- 0.05
2.40 ± 0.10
0.20
0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC
7° NOM
0.04 REF
0.055 ± 0.045
0.15 ± 0.05
+ 0.10
1.00 - 0.065
0.9625 ± 0.0375
3.00 ± 0.10
4° ± 4°
0.45 ± 0.15
0.010
2.75 ± 0.25
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
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3143.2006.05.1.0
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