View AAT3158ITP-T1_611831.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

AAT3158
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications General Description
The AAT3158 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 AAT3158 is capable of driving up to four LED channels at 20mA per channel 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 1F flying capacitors and two small 1F capacitors at VIN and VOUT) make this part ideally suited for small, battery-powered applications. AnalogicTech's S2CwireTM (Simple Serial ControlTM) serial digital input is used to enable, disable, and set current for each LED with 16 settings down to 50A. The low current mode supply current can be as low as 50A to save power. Each output of the AAT3158 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 1A. The AAT3158 is available in a Pb-free, space-saving 2.85x3.0mm TSOPJW-12 package.
Features
* * * * * * * * * * * *
ChargePumpTM
VIN Range: 2.7V to 5.5V Fully Programmable Current with Single Wire -- 16 Current Levels -- Four Low Current Settings Down to 50A Low IQ (50A) for Low Current Mode Tri-Mode 1X, 1.5X, and 2X Charge Pump for Maximum Efficiency and VF Coverage Drives Up to Four LED Channels No Inductors, Low Noise Operation 1MHz Constant Switching Frequency Small Application Circuit Built-In Thermal Protection Automatic Soft-Start IQ <1A in Shutdown 2.85x3mm TSOPJW-12 Package
Applications
* * * * Color (RGB) Lighting Programmable Current Sinks White LED Backlighting White Photo Flash for Digital Still Cameras
Typical Application
C1+ C2+ C2VOUT COUT 1F
C1 1F 2.7V to 5.5V CIN 1F
C2 1F
C1VIN
AAT3158
GND D1 D2 D3 D4
D1
D2
D3
D4
EN/SET
EN/SET
3158.2006.02.1.0
1
AAT3158
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications Pin Descriptions
Pin #
1 2 3 4 5 6 7 8 9 10 11 12
Symbol
D4 EN/SET C1+ C1VOUT C2+ C2VIN GND D3 D2 D1
Function
Current sink input #4. S2Cwire serial interface control pin. Flying capacitor 1 positive terminal. Connect a 1F capacitor between C1+ and C1-. Flying capacitor 1 negative terminal. Charge pump output to drive load circuit. Requires 1F capacitor connected between this pin and ground. Flying capacitor 2 positive terminal. Connect a 1F capacitor between C2+ and C2-. Flying capacitor 2 negative terminal. Input power supply. Requires 1F capacitor connected between this pin and ground. Ground. Current sink input #3. Current sink input #2. Current sink input #1.
Pin Configuration
TSOPJW-12 (Top View) D4 EN/SET C1+ C1VOUT C2+ D1 D2 D3 GND VIN C2-
1 2 3 4 5 6
12 11 10 9 8 7
2
3158.2006.02.1.0
AAT3158
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
-0.3 to 6 -0.3 to VIN + 0.3 150 -40 to 150 300
Units
V V mA C C
Thermal Information3
Symbol
PD JA
Description
Maximum Power Dissipation Maximum Thermal Resistance
4
Value
0.625 160
Units
W C/W
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 6.25mW/C above 25C. 3158.2006.02.1.0
3
AAT3158
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications Electrical Characteristics1
CIN = COUT = C1 = C2 = 1.0F; TA = -40C to +85C, unless otherwise noted. Typical values are TA = 25C, VIN = 3.6V. Symbol Description Conditions Min
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 50A Setting, 1X Mode EN/SET = 0 18 VF:D1:D4 = 3.6V 0.3 1 1 50 20 0.5 150 100 1000 VIN = 2.7V VIN = 5.5V 0.4 1.4 0.3 50 75 500 500 1 75 1 22 1 A A mA % mV s kHz V V s ns s s s A
Typ
Max
5.5 1 3
Units
V
Input Power Supply VIN Operation Range
ICC
Operating Current
mA
Shutdown Current ISINK Average Current Accuracy I(D-Match) Current Matching2 1X to 1.5X or 1.5X to 2X Transition VTH Threshold at Any ISINK 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
ISHDN IDX
-1
1. The AAT3158 is guaranteed to meet performance specifications over the -40C to +85C 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
3158.2006.02.1.0
AAT3158
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications Typical Characteristics
Efficiency vs. Supply Voltage
100 90 6mA/ch VF = 3V 20mA/ch VF = 3.4V
Turn-On to 1X Mode
(VIN = 4.2V; 20mA/ch Load)
Efficiency (%)
80 70 60 50 40 30 2.7 2.9 3.1 3.3 500A/ch VF = 2.7V
EN/SET (2V/div) VOUT (2V/div) VSINK (1V/div) IIN (100mA/div) Time (100s/div)
3.5
3.7
3.9
4.1
4.3
4.5
Supply Voltage (V)
Turn-On to 1.5X Mode
(VIN = 3.5V; 20mA/ch Load)
Turn-On to 2X Mode
(VIN = 2.8V; 20mA/ch Load)
EN/SET (2V/div) VOUT (2V/div) VSINK (1V/div) IIN (200mA/div) Time (100s/div)
EN/SET (2V/div) VOUT (2V/div) VSINK (500mV/div) IIN (500mA/div) Time (100s/div)
Turn-Off from 1.5X Mode
(VIN = 3.5V; 20mA/ch Load)
22.0 21.5 21.0 20.5 20.0 19.5 19.0 18.5 18.0 -40
Diode Current vs. Temperature
(20mA/channel)
EN/SET (2V/div) VF (1V/div) IIN (100mA/div)
Diode Current (mA)
ID1 ID4 ID2 ID3
-25 -10 5 20 35 50 65 80 95
Time (100s/div)
Temperature (C)
3158.2006.02.1.0
5
AAT3158
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications Typical Characteristics
Load Characteristics
(VIN = 3.7V; 1.5X Mode; 20mA/ch Load)
Load Characteristics
(VIN = 3.5V; 1.5X Mode; 14mA/ch Load)
VIN (20mV/div) VCP (40mV/div) VSINK (20mV/div)
VIN (20mV/div) VCP (40mV/div) VSINK (20mV/div)
Time (500ns/div)
Time (500ns/div)
Load Characteristics
(VIN = 2.9V; 2X Mode; 20mA/ch Load)
Load Characteristics
(VIN = 2.9V; 2X Mode; 14mA/ch Load)
VIN (20mV/div) VCP (40mV/div) VSINK (40mV/div)
VIN (20mV/div) VCP (40mV/div) VSINK (40mV/div)
Time (500ns/div)
Time (500ns/div)
Input Ripple vs. Input Voltage
14.0 12.0
20mA/ch 14mA/ch
Input Ripple (mV)
10.0 8.0 6.0 4.0 2.0 0.0 2.5
10mA/ch
3.0 3.5 4.0 4.5 5.0 5.5
Input Voltage (V)
6
3158.2006.02.1.0
AAT3158
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications Typical Characteristics
EN/SET Latch Timeout vs. Input Voltage
EN/SET Latch Timeout (s)
350 350
EN/SET Off Timeout vs. Input Voltage
EN/SET Off Timeout (s)
300 250 200 150 100 50 0
300 250 200 150 100 50 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
-40C
-40C
25C
85C
25C
85C
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5
Input Voltage (V)
Input Voltage (V)
Enable Threshold High vs. Input Voltage
Enable Threshold High (V) Enable Threshold Low (V)
1.4 1.2 1.0 0.8 0.6 0.4 2.7 1.4 1.2 1.0 0.8 0.6 0.4
Enable Threshold Low vs. Input Voltage
-40C
-40C
25C
85C
25C
2.7 3.1 3.5 3.9 4.3
85C
4.7 5.1 5.5
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Input Voltage (V)
3158.2006.02.1.0
7
AAT3158
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications Functional Block Diagram
C1+ C1- C2+ C2-
V IN
1X, 1.5X, 2X Charge Pump
VOUT
Soft-Start Control 1MHz Oscillator Voltage Reference D/A 6 x 16 bit ROM D/A D/A D/A
D1 D2 D3 D4 GND
EN/SET
S2Cwire Interface
Functional Description
The AAT3158 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 AAT3158 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 AAT3158 requires only four external components: two 1F ceramic capacitors for the charge pump flying capacitors (C1 and C2), one 1F ceramic input capacitor (CIN), and one 0.33F to 1F 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 8
connected to VOUT; otherwise, the part will operate only in 2X charge pump mode. The S2Cwire serial interface enables the AAT3158 and sets the current sink magnitudes.
Constant Current Output Level Settings
The constant current sink levels for D1 to D4 are set via the serial interface according to a logarithmic scale for the first 12 codes, and a separate low current scale for the last 4 codes. For the first 12 codes, each code is approximately 1.5dB lower than the previous code. In this manner, LED brightness appears linear with each increasing code count. 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. Since the input current sinks of the AAT3158 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
3158.2006.02.1.0
AAT3158
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
forget it." With its high-speed serial interface (1MHz data rate), the input sink current of the AAT3158 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. 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 for time TLAT, the programmed current becomes active and the internal data register is reset to zero. 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 low for an amount of time greater than TOFF, the AAT3158 enters into shutdown mode and draws less than 1A from VIN. The internal data register is reset to zero during shutdown.
S2Cwire Serial Interface
The current level magnitude is controlled by AnalogicTech's 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. Output (mA/Ch)
20 18 16 14 12.5 11 9.5 8
Auto-Disable Feature
The AAT3158 is equipped with an auto-disable feature for each LED channel. After the IC is enabled and started up, a test current of 100A (typical) is forced through each sink channel. The channel will be disabled if the voltage of that particular SINK pin does not drop to certain threshold. This feature is very convenient for disabling an unused channel or during an LED fail short event.
Data
1 2 3 4 5 6 7 8
Data
9 10 11 12 13 14 15 16
Output (mA/Ch)
6 4 3 2 1 0.5 0.1 0.05
Thermal Protection
The AAT3158 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 of the VOUT pin.
The S2Cwire serial interface has flexible timing. Data can be clocked-in at speeds greater than
S2Cwire Serial Interface Timing
T HI T LO TLAT TOFF
EN/SET
1 2 n n <= 16
Data Reg
1
n
0
3158.2006.02.1.0
9
AAT3158
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications Applications Information
LED Selection
Although AAT3158 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. 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 AAT3158 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. 1F 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 AAT3158. 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.
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.
Device Switching Noise Performance
The AAT3158 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 AAT3158 soft-start feature prevents noise transient effects associated with inrush currents during start-up of the charge pump circuit.
Ceramic Capacitor Materials
Ceramic capacitors less than 0.1F 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 2.2F, are often available in lowcost Y5V and Z5U dielectrics, but capacitors greater than 1F are typically not required for AAT3158 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.
Capacitor Selection
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 100m. A value of
10
3158.2006.02.1.0
AAT3158
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications Ordering Information
Package
TSOPJW-12
Marking1
RHXYY
Part Number (Tape and Reel)2
AAT3158ITP-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
0.10 0.20 + 0.05 -
2.40 0.10
0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC
2.85 0.20
7 NOM 3.00 0.10
0.9625 0.0375 + 0.10 1.00 - 0.065
0.04 REF
0.055 0.045
4 4
0.010
0.15 0.05
0.45 0.15 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.
(c) Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Customers are advised 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
3158.2006.02.1.0
11

▲Up To Search▲

Price & Availability of AAT3158ITP-T1

	To Download AAT3158ITP-T1 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .