Analogic AAT3152 High efficiency 1x/1.5x/2x charge pump for white led application Datasheet

AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
General Description
Features
The AAT3152 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 AAT3152 is capable of driving
four-channel LEDs from a 2.7V to 5.5V input. The
current sinks 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 this part ideally suited for small, battery-powered applications.
•
•
•
•
•
•
•
•
•
•
•
•
AnalogicTech's S2Cwire™ (Simple Serial Control™)
serial digital input is used to enable, disable, and
set current for each LED with eight settings (20mA
down to 50µA) including main/sub-display group
control. The AAT3152 consumes extremely low current internally (50µA typical) at light load for optimized efficiency.
Each output of the AAT3152 is equipped with builtin protection for VOUT short-circuit and auto-disable
for load short-circuit conditions. 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.
ChargePump™
VIN Range: 2.7V to 5.5V
Fully Programmable Current with Single Wire
— Eight-Step Current: 20mA to 50µA
— Individual Main-Sub Group Control
— Low IQ (50µA) at Light Load
Tri-Mode 1X, 1.5X, and 2X Charge Pump for
Maximum Efficiency and VF Coverage
Drives 1-4 Channels of LEDs
No Inductors, Low Noise Operation
1MHz Constant Switching Frequency
Small Application Circuit
Built-In Thermal Protection
Built-In Auto-Disable for Short-Circuit
Automatic Soft Start
IQ <1µA in Shutdown
Thermally-Enhanced 3x3mm 12-Pin TDFN
Package
Applications
•
•
•
•
Color (RGB) Lighting
Programmable Current Sinks
White LED Backlighting
White Photo Flash for Digital Still Cameras
The AAT3152 is available in a Pb-free, space-saving, thermally-enhanced 12-pin 3x3mm TDFN
package.
Typical Application
VIN
2.7V to 5.5V
C1+
C1
1µF
CIN
1µF
C1C2+
C2
1µF
AAT3152
C2VOUT
D1
EN/SET
D2
D3
D4
COUT
1µF
D1
EN/SET
D2
D3
GND
3152.2005.08.1.2
D4
1
AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
Pin Descriptions
Pin #
Symbol
1
D4
2
EN/SET
3
C1+
Flying capacitor 1 positive terminal. Connect a 1µF capacitor between C1+
and C1-.
4
C1-
Flying capacitor 1 negative terminal.
5
VOUT
Charge pump output to drive load circuit. Requires 1µF capacitor connected
between this pin and ground.
6
C2+
Flying capacitor 2 positive terminal. Connect a 1µF capacitor between C2+
and C2-.
7
C2-
Flying capacitor 2 negative terminal.
8
VIN
Input power supply. Requires 1µF capacitor connected between this pin and
ground.
9
GND
Ground.
10
D1
Current sink input #1.
11
D2
Current sink input #2.
12
D3
Current sink input #3.
EP
Function
Current sink input #4.
S2Cwire serial interface control pin.
Exposed paddle (bottom); connect to GND directly beneath package.
Pin Configuration
TDFN33-12
(TopView)
D4
EN/SET
C1+
C1VOUT
C2+
2
1
12
2
11
3
10
4
9
5
8
6
7
D3
D2
D1
GND
VIN
C2-
3152.2005.08.1.2
AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
Absolute Maximum Ratings1
Symbol
VIN
VEN/SET
IOUT2
TJ
TLEAD
Description
Input Voltage
EN/SET 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
150
-40 to 150
300
V
V
mA
°C
°C
Value
Units
2.0
50
W
°C/W
Thermal Information3
Symbol
PD
θJA
Description
4
Maximum Power Dissipation
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. Based on long-term current density limitation.
3. Mounted on an FR4 board.
4. Derate 20mW/°C above 25°C.
3152.2005.08.1.2
3
AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
Electrical Characteristics1
CIN = COUT = C1 = C2 = 1.0µF; TA = -40°C to +85°C, unless otherwise noted.
Typical values are TA = 25°C, VIN = 3.6V.
Symbol
Description
Conditions
Input Power Supply
VIN
Operation Range
ICC
ISHDN
IDX
Operating Current
Shutdown Current
ISINK Average Current Accuracy
I(D-Match)
Current Matching Between Any
Two Current Sink Inputs2, 3
VTH
1X to 1.5X or 1.5X to 2X Transition
Threshold at Any Current Sink Pin
Charge Pump Section
TSS
Soft-Start Time
FCLK
Clock Frequency
EN/SET
VEN(L)
Enable Threshold Low
VEN(H)
Enable Threshold High
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
Min
Typ
Max
Units
5.5
1
V
0.3
1
3
mA
1.5
3
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
ISET = 20mA, TA = 25°C
VF:D1:D4 = 3.6V
50
0.5
µA
µA
%
%
150
mV
100
1000
µs
kHz
1
10
-10
0.4
1.4
0.3
75
50
-1
75
500
500
1
V
V
µs
ns
µs
µs
µs
µA
1. The AAT3152 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 at IOUT = 20mA and 2mA.
3. Specification applies only to the tri-mode charge pump.
4
3152.2005.08.1.2
AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
Typical Characteristics
Efficiency vs. Supply Voltage
Turn-On to 1X Mode
(VIN = 4.2V; 20mA Load)
100
20mA
VF = 3.4V
10mA
VF = 3.1V
EN
(2V/div)
Efficiency (%)
90
80
CP
(2V/div)
VSINK
(500mV/div)
70
60
IIN
(200mA/div)
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 = 3.5V; 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)
20.4
EN
(2V/div)
Channel 2
Current (mA)
20.2
VF
(1V/div)
IIN
(100mA/div)
20.0
Channel 4
19.8
Channel 3
Channel 1
19.6
19.4
19.2
19.0
-40
500µ
µs/div
3152.2005.08.1.2
-20
0
20
40
60
80
Temperature (°°C)
5
AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
Typical Characteristics
Load Characteristics
Load Characteristics
(VIN = 3.7V; 1.5X Mode; 14mA Load)
(VIN = 2.7V; 2X Mode; 14mA 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 = 3.9V; 1.5X Mode; 20mA Load)
(VIN = 2.9V; 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
TOFF vs. VIN
TLAT vs. VIN
350
400
300
350
300
-40°C
TOFF (µ
µs)
TLAT (µ
µs)
250
200
150
100
25°C
85°C
50
200
150
25°C
85°C
100
50
0
6
-40°C
250
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)
3152.2005.08.1.2
AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
Typical Characteristics
VIH vs. VIN
18
1.2
16
1.1
1
14
-40°C
0.9
12
VIH (V)
Amplitude (mV)
Input Ripple vs. Input Voltage
10
8
20mA
6
0.7
0.6
25°C
85°C
0.5
10mA
4
0.8
0.4
2
0.3
0
0.2
2.5
2.67
2.84
3.01
3.18
3.35
3.52
3.69
3.86
4.03
4.2
Input Voltage (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
VIH (V)
0.9
-40°C
0.8
0.7
0.6
25°C
0.5
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)
3152.2005.08.1.2
7
AAT3152
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
VIN
VOUT
Soft-Start
Control
1MHz
Oscillator
Voltage
Reference
6 x 16 bit
ROM
EN/SET
D/A
D1
D/A
D2
D/A
D3
D/A
D4
S2Cwire
Interface
6 x 16 bit
ROM
GND
Functional Description
The AAT3152 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 AAT3152
charge pump is enabled when any of the four 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
8
automatically transition to 2X mode. The AAT3152
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 sink inputs (D1 to D4)
can drive four individual LEDs with a maximum current of 20mA 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 AAT3152 and sets the current sink magnitudes. S2Cwire addressing allows
independent control of two groups of current sink
input: D1-D3 and D4.
3152.2005.08.1.2
AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
Constant Current Output Level Settings
The constant current sink levels for D1 to D4 are
set via the serial interface. 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 (up to 1MHz data rate), the input
sink current of the AAT3152 can be changed successively to brighten or dim LEDs, giving the users
real-time control of LED brightness. Because the
inputs D1 to D4 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.
S2Cwire Serial Interface
The current sink input magnitude on the AAT3152 is
controlled by AnalogicTech's S2Cwire serial digital
input. It relies on the number of rising edges of the
EN/SET pin to address and load the registers.
S2Cwire latches data or address after the EN/SET
pin has been held high for time TLAT. The interface
records rising edges of the EN/SET pin and
decodes them into 16 different states, as indicated
in the Current Setting table. There are four brightness levels for main or sub-display group with the
possibility of individually turning ON or OFF each
group. To further optimize power efficiency, the
AAT3152 also offers four low-current levels for dim
LED operation (Data 13-16). During this low-current
mode, the internal supply current reduces to only
80µA typical.
The counter can be clocked at speeds up to 1MHz,
such that intermediate states are not visible. The
first rising edge of EN/SET enables the IC and initially sets the output LED current to 20mA. Once
the final clock cycle is input for the desired brightness level, the EN/SET pin is held high to maintain
the device output current at the programmed level.
The device is disabled 500µs (TOFF) after the
EN/SET pin transitions to a logic low state.
3152.2005.08.1.2
AAT3152 Current Setting
Data
Main Group
(D1-D3)
IOUT (mA)
Sub Group
(D4)
IOUT (mA)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
20
14
10
7
20
14
10
7
0
0
0
0
0.05
0.5
1
2
20
14
10
7
0
0
0
0
20
14
10
7
0.05
0.5
1
2
The EN/SET timing is designed to accommodate a
wide range of data rates. After the first rising edge
of EN/SET, the charge pump is enabled and reaches full capacity after the soft-start time (TSS). During
the soft-start time, multiple clock pulses may be
entered on the EN/SET pin to set the final output
current level with a single burst of clocks.
Alternatively, the EN/SET clock pulses may be
entered one at a time to gradually increase the
LED brightness over any desired time period. The
current outputs remain constant as long as
EN/SET remains in a logic high state. The current
outputs are switched off after EN/SET has
remained in a low state for at least the TOFF timeout
period; then, the AAT3152 enters shutdown mode
and draws less than 1µA from VIN. Data are reset
to 0 during shutdown.
9
AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
S2Cwire Serial Interface Timing
T HI
T LO
TOFF
TLAT
EN/SET
1
2
Data Reg
n
n <= 16
1
Auto-Disable Feature
The AAT3152 is equipped with an auto-disable feature for each LED channel. After the IC is enabled
and started up, a test current of 150µA (typical) is
forced through each sink channel. The channel will
be disabled if the voltage of that particular current
sink pin does not drop to a certain threshold. This
feature is very convenient for disabling an unused
channel (by tying the DX pin to VOUT) or during an
LED fail short event.
Thermal Protection
The AAT3152 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 VOUT pin.
Applications Information
LED Selection
Although the AAT3152 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
10
n
0
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 AAT3152 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 AAT3152 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-topeak, typically ten times less than inductor-based
DC/DC boost converter white LED backlight solutions. The AAT3152 soft-start feature prevents
noise transient effects associated with in-rush currents during start-up of the charge pump circuit.
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 per-
3152.2005.08.1.2
AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
formance. 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 the capacitor size may be decreased.
ly measured in milliohms for ceramic capacitors and
can range to more than several ohms for tantalum
or aluminum electrolytic capacitors.
Ceramic Capacitor Materials
Ceramic composition capacitors are highly recommended over all other types of capacitors for use
with the AAT3152. 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 to 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 lowcost Y5V and Z5U dielectrics, but capacitors
greater than 1µF are typically not required for
AAT3152 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.
Equivalent Series Resistance
Thermal Protection
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 typical-
The AAT3152 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 VOUT pin.
Capacitor Characteristics
3152.2005.08.1.2
11
AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TDFN33-12
NQXYY
AAT3152IWP-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
2.40 ± 0.05
Detail "B"
3.00 ± 0.05
Index Area
(D/2 x E/2)
0.3 ± 0.10 0.16 0.375 ± 0.125
0.075 ± 0.075
3.00 ± 0.05
1.70 ± 0.05
Top View
Bottom View
Pin 1 Indicator
(optional)
0.23 ± 0.05
Detail "A"
0.45 ± 0.05
0.1 REF
0.05 ± 0.05
0.229 ± 0.051
+ 0.05
0.8 -0.20
7.5° ± 7.5°
Detail "B"
Option A:
C0.30 (4x) max
Chamfered corner
Side View
Option B:
R0.30 (4x) max
Round corner
Detail "A"
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
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, and advise customers to obtain the latest
version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale
supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability.
AnalogicTech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech’s standard warranty. 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.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
12
3152.2005.08.1.2