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AAT3172
High Current LED Flash Driver Charge Pump IC General Description
The AAT3172 is a high output current, high efficiency, low noise, low profile charge pump DC/DC converter, ideal for multi-function LED photo-flash applications where solution cost, size, and efficiency are critical. The dual charge pump in the AAT3172 is capable of delivering 600mA peak output current. Two current-controlled paths are available for users of dual flash LEDs that prefer current matching. Each LED channel can be easily programmed in 32 steps with a single GPIO output through the AS2CwireTM (Advanced Simple Serial ControlTM) interface. This allows smooth transitions and flexible adjustment of brightness in flash or other lighting modes. The tri-mode (1X/1.5X/2X) operation of the internal charge pump offers excellent power efficiency for both flash and movie modes. Combined with a low external parts count (two 1F flying capacitors and one small bypass capacitor at VIN and OUT), the AAT3172 is ideally suited for small, battery-powered applications. The AAT3172 has a thermal management system to protect the device in the event of a short-circuit condition at the output pin. Built-in soft-start circuitry prevents excessive inrush current during start-up. The shutdown feature disconnects the load from VIN and reduces quiescent current to less than 1.0A. The AAT3172 is available in the Pb-free, thermallyenhanced, 12-pin 3x3 TDFN package.
Features
* * * * * * * * * * * * * *
ChargePumpTM
VIN Range: 2.7V to 5.5V 600mA Peak Output Current Tri-Mode 1X/1.5X/2X in Current Mode Voltage Mode Operation: 1.5X, 100mA Dual Regulated Current Sinks Current Match Between Current Sinks 32 Current Steps Set by AS2Cwire 1F Input, Output, and Flying Capacitors <1.0A of Shutdown Small Application Circuit No Inductors Automatic Soft Start 12-Pin TDFN 3x3 Package -40C to +85C Temperature Range
Applications
* * * * Camera Phones Digital Still Cameras (DSCs) PDAs and Notebook PCs Smart Phones
Typical Application
C1 1F C2 1F
C1+ 2.7V to 5.5V
C IN 4.7F
C1- C2+
C2VOUT
VIN
AAT3172
C OUT 2.2F
Flash LED 1
Flash LED 2
F1 EN/SET EN/SET GND F2
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AAT3172
High Current LED Flash Driver Charge Pump IC Pin Descriptions
Pin #
1, 12 2 3 4 5 6 7 8 9 10 11 EP
Symbol
VIN C1+ C1GND F1 F2 EN/SET N/C C2C2+ VOUT
Function
Input power supply pin. Requires 4.7F bypass capacitor to ground. Flying capacitor C1 positive terminal. Connect a 1.0F capacitor between C1+ and C1-. Flying capacitor C1 negative terminal. Ground connection. Current sink input #1. Current sink input #2. AS2Cwire serial interface control pin. No connection. Flying capacitor C2 negative terminal. Flying capacitor C2 positive terminal. Connect a 1F capacitor between C2+ and C2-. Charge pump output. Requires 2.2F capacitor connected between this pin and ground. Exposed paddle (bottom); connect to GND directly beneath package.
Pin Configuration
TDFN33-12 (Top View)
VIN C1+ C1GND F1 F2
1 2 3 4 5 6
12 11 10 9 8 7
VIN VOUT C2+ C2N/C EN/SET
2
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AAT3172
High Current LED Flash Driver Charge Pump IC Absolute Maximum Ratings1
TA = 25C, unless otherwise noted. Symbol
VIN VEN VEN(MAX) IOUT TJ TS TLEAD
Description
Input Voltage EN to GND Voltage Maximum EN to Input Voltage Maximum DC Output Current (continuous) Operating Junction Temperature Range Storage Temperature Range Maximum Soldering Temperature (at leads, 10 sec)
Value
-0.3 to 6.0 -0.3 to 6.0 VIN + 0.3 400 -40 to 150 -65 to 150 300
Units
V V V mA C C C
Thermal Information2
Symbol
JA PD
Description
Maximum Thermal Resistance Maximum Power Dissipation
Value
50 2.0
Units
C/W 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. Mounted on an FR4 board. 3172.2005.11.1.1
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AAT3172
High Current LED Flash Driver Charge Pump IC Electrical Characteristics1
CIN = 4.7F, COUT = 2.2F, 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 ON/OFF Standby Mode, Code Address = 4, Data = 2 1X, No Load Current 3.0 VIN 5.5, 1.5X Mode, No Load Current 3.0 VIN 5.5, 2X Mode, No Load Current EN = 0 VF = 3.6V VIN = 3.6V, TA = 25C, 428mA Code Address = 3, Data = 2; Code Address = 0, Data = 4 VIN = 3.6V, TA = 25C, 100mA Code Address = 3, Data =1; Code Address = 0, Data = 1 TA = 25C, Code 1, HI Scale EN/SET Code Address = 5, Data = 2 5.5 10 300 2.0 3.0 600 8
Typ Max Units
5.5 V V A 4.0 6.0 1.0
Power Supply VIN Input Voltage Range VOUT(MAX) Maximum Output Voltage
ICC
Operating Current
mA A mA %
ISHDN(MAX) IOUT(MAX)2 I(D-Match) I(D-Match) IDX FCLK VREG TSS EN/SET VIL VIH TEN/SET LO TEN/SET HI MIN TEN/SET HI MAX TOFF TLAT Input Current
VIN Pin Shutdown Current Maximum Output Current Current Matching Between Outputs; High Current Current Matching Between Outputs; Low Current Output Current Accuracy Clock Frequency Voltage Mode Regulation Soft-Start Time
8 270 4.1 2 4.5 200 330 4.9
% mA MHz V s V V s ns s s s A
Enable Threshold Low VIN = 2.7V Enable Threshold High VIN = 5.5V EN/SET Low Time Minimum EN/SET High Time Maximum EN/SET High Time EN/SET Off Timeout EN/SET Latch Timeout EN/SET Input Leakage
0.4 1.4 0.3 50 75 500 500 1 75
-1
1. The AAT3172 is guaranteed to meet performance specifications from 0C to 70C. Specification over the -40C to +85C operating temperature range is assured by design, characterization, and correlation with statistical process controls. 2. Mounted on an FR4 board.
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AAT3172
High Current LED Flash Driver Charge Pump IC Typical Characteristics
VIN = 3.6V, CIN = 4.7F, COUT = 2.2F, C1 = C2 = 1F, TA = 25C, unless otherwise noted. Efficiency vs. Supply Voltage
100 90
Turn-On to 1X Mode
(VIN = 4.2V; 50mA/ch Load)
Efficiency (%)
80 70 60 50 40 30
50mA/ch VF = 2.8V
EN (2V/div) VOUT (2V/div) VSINK (1V/div) IIN (200mA/div)
152mA/ch VF = 3.0V 95mA/ch VF = 2.9V
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
Supply Voltage (V)
200s/div
Turn-On to 1.5X Mode
(VIN = 3.2V; 50mA/ch Load)
Turn-On to 1X Mode
(VIN = 4.2V; 300mA/ch Load)
EN (2V/div) VOUT (2V/div) VSINK (1V/div) IIN (200mA/div) 200s/div
EN (2V/div) VOUT (2V/div) VSINK (1V/div) IIN (500mA/div) 500s/div
Turn-On to 2X Mode
(VIN = 3.2V; 300mA/ch Load) EN (2V/div) VF (1V/div)
Turn-Off from 1.5X Mode
(VIN = 3.2V; 50mA/ch Load)
EN (2V/div) VOUT (2V/div) VSINK (1V/div) IIN (500mA/div) 500s/div
IIN (200mA/div)
200s/div
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AAT3172
High Current LED Flash Driver Charge Pump IC Typical Characteristics
VIN = 3.6V, CIN = 4.7F, COUT = 2.2F, C1 = C2 = 1F, TA = 25C, unless otherwise noted. Load Characteristic
(VIN = 3.0V; 1.5X Mode; 50mA/ch Load)
Load Characteristic
(VIN = 3.6V; 1.5X Mode; 152mA/ch Load)
VIN (100mV/div) VOUT (200mV/div) VSINK (200mV/div)
VIN (100mV/div) VOUT (200mV/div) VSINK (200mV/div)
2s/div
2s/div
Load Characteristic
(VIN = 2.8V; 2X Mode; 152mA/ch Load)
4.8
Voltage Mode Load Regulation
Output Voltage (V)
VIN (100mV/div) VOUT (200mV/div)
4.7 4.6 4.5 4.4 4.3 4.2 4.1 0 15 30 45 60 75 90 105 120 135 150
VIN = 4.2V
VIN = 3.7V VIN = 3.3V
VSINK (200mV/div)
2s/div
Load Current (mA)
Voltage Mode Line Regulation
4.8
Voltage Mode Load Response
(VIN = 3.7V)
Output Voltage (V)
4.7 4.6 4.5 4.4 4.3 4.2 4.1 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
IOUT = 10mA
VOUT (100mV/div) 100mA IOUT (100mA/div) 10mA
4.51V
IOUT = 120mA IOUT = 80mA IOUT = 30mA
Input Voltage (V)
5ms/div
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AAT3172
High Current LED Flash Driver Charge Pump IC Typical Characteristics
VIN = 3.6V, CIN = 4.7F, COUT = 2.2F, C1 = C2 = 1F, TA = 25C, unless otherwise noted. Voltage Mode Load Response
(VIN = 3.3V)
Voltage Mode Line Response
(100mA Load)
VOUT (100mV/div) 100mA IOUT (100mA/div) 10mA
4.50V
4.0V VIN (500mV/div) 3.6V VOUT (200mV/div) 4.5V
5ms/div
1ms/div
TLAT vs. VIN
160 140 120 180
TOFF vs. VIN
25C -40C 85C
25C -40C TOFF (s) 85C
160 140 120 100 80 60 40 20 0
TLAT (s)
100 80 60 40 20 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
Input Voltage (V)
Input Voltage (V)
VIH vs. VIN Over-Temperature
1.0 0.9 0.8 1.0
VIL vs. VIN Over-Temperature
-40C
0.9 0.8
-40C
VIH (V)
0.7
VIL (V)
85C 25C
0.7 0.6 0.5 0.4 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
0.6 0.5 0.4 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
85C 25C
Input Voltage (V)
Input Voltage (V)
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AAT3172
High Current LED Flash Driver Charge Pump IC Functional Block Diagram
C1+
C1-
C2+
C2-
VIN
Charge Pump Section 1 Charge Pump Section 2
2MHz Oscillator Soft Start Control
OUT
F1
EN/SET
System Control; AS 2Cwire
F2
GND
Functional Description
The AAT3172 is a high efficiency, low noise, dual stage tri-mode 1X/1.5X/2X charge pump device intended for photo-flash LED applications. The AAT3172 requires only four external components: two 1.0F ceramic capacitors for the charge pump flying capacitors, one 4.7F ceramic capacitor for CIN, and one 2.2F ceramic capacitor for COUT. The charge pump is designed to deliver continuous load currents up to 400mA. For short duration flash events, the AAT3172 can deliver peak load currents up to 600mA over a 0C to 70C operating temperature range. The dual stage charge pump section contains soft-start circuitry to prevent excessive in-rush current during start-up. System efficiency is maximized with a tri-mode, dual stage charge pump topology. The internal clock oscillator, which operates at 2MHz, allows the use of small external components.
The tri-mode charge pump architecture optimizes power conversion efficiency. Depending upon the combination of load current, input voltage, and nominal LED forward voltage, the charge pump will operate in a 1X, 1.5X, or 2X mode to generate the output voltage required to power the load for a programmed constant current setting. This results in significant power savings over voltage doubling architectures, especially when the LEDs are continuously operated at lower current levels in movie viewing or flashlight modes.
Constant Current Channels
The AAT3172 contains two programmable constant current sinks for integrated flash circuit control. Efficiency is optimized with the low dropout characteristic of the current sinks. The low dropout performance extends the battery operating range for 1X and 1.5X modes, improving efficiency and extending battery life. Each constant current sink is
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AAT3172
High Current LED Flash Driver Charge Pump IC
programmable through the AS2Cwire serial interface. Independent current settings can be used for a multistage flash LED control. This feature allows users to conveniently drive separate dual flash LEDs directly while achieving good brightness matching. Also, F1 and F2 can be connected together for single output configuration.
Constant Current Sink Nominal Programming Levels
Data
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
300mA HI Scale ISINK (mA/chnl)
300 267 238 214 190 167 152 133 119 105 95 86 76 67 62 0
50mA LO Scale ISINK (mA/chnl)
50 44 40 36 32 28 25 22 20 17 16 14 13 11 10 0
Modes of Operation
In addition to the data registers that set the current levels for the two current sinks, the AAT3172 has three mode registers. Register 3 is the HI/LO mode register. It sets the maximum per channel current level to either 300mA or 50mA. Each channel can be set independently so one channel can be for flash while the other can be in a low constant current mode. Register 4 is the ON/OFF register. When set with Data = 1, both current sources are enabled (default); when set with Data = 2, both current sources are disabled. When Register 4 is set to OFF, the device is in standby mode with significantly reduced quiescent current. The AAT3172 also includes a regulated output voltage mode setting. By setting Register 6 with Data = 2 for voltage mode, the charge pump delivers a regulated 4.5V output that continuously operates in 1.5X mode. It is suitable for driving loads of up to 100mA. The voltage mode may be used to drive LEDs with ballast resistors. Driving either F1 or F2 in current mode will override the voltage mode state until F1 and F2 are set back to zero current by either data or mode register. Setting Register 5 with Data = 1 will reset the mode back to current mode and the charge pump output voltage will regulate appropriately.
AS2Cwire Serial Interface
The AAT3172 utilizes the AS2Cwire serial interface to enable/disable the charge pump, set the operating mode, and adjust the output current level of each constant current sink. Each current sink can be independently programmed with sixteen current levels (see table below). AS2Cwire incorporates addressing to program the operating modes and current level settings.
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 0 is signified by 17 rising edges, Address 1 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 that address are allowed where only data is issued. When EN/SET is held low for an amount of time greater than TOFF, the AAT3172 enters into shutdown mode and draws less than 1A from the supply. Address 0 is the default address on the first rising edge after the AAT3172 has been disabled.
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AAT3172
High Current LED Flash Driver Charge Pump IC
After shutdown, if only data is issued with the first rising edge (i.e., 1 - 16 edges, no address given), both current sinks will be programmed since the default will be Address 0.
ON/OFF Register (Address 4)
Data
1 2
MODE
ON OFF
AS2Cwire Serial Interface Addressing
EN/SET Address Rising Edges
0 1 2 3 4 5 6 17 18 19 20 21 22 23
Voltage Register (Address 6)
Data Register
F1 and F2 Current Scale F1 Current Scale F2 Current Scale HI/LO ON/OFF Reserved Voltage/Current Mode
Data
1 2
MODE
Current Voltage
Thermal Protection
The AAT3172 has a 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 OUT pin.
HI/LO Scale Register (Address 3)
Data
1 2 3 4
F1
LO HI LO HI
F2
LO HI HI LO
AS2Cwire Serial Interface Timing
Address
T HI T LO TLAT TLAT
Data
EN/SET
1 2 17 18 1 2... n <= 16
Address
0
1
Data Reg 1
0
n-1
Data Reg 2
0
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AAT3172
High Current LED Flash Driver Charge Pump IC Applications Information
AS2Cwire Programming
Generally, programming the AAT3172 is achieved by submitting bursts of address and data edges to the EN/SET pin. However, in some cases multiple bursts of address and data are needed to enable a particular operating mode. In other cases, only a single burst of data edges is required. To enable both flash channels to a current setting on the LO scale, the user submits a single burst of address and data edges. To enable both flash channels to a current setting on the HI scale, the user must submit a burst of address and data edges to program the current setting level, and then submit a second burst of address and data edges to program the HI/LO scale register to the HI scale. Shortcuts can also be used. If the device is in shutdown, both flash channels can be enabled to a setting on the LO scale by just giving a single burst of data edges. The address edges are not needed because all registers are reset during shutdown and address 0 is the default. Further, a single burst of data edges can be used to change from one setting to another for the last address. The address register is not reset after each write; therefore, submitting address edges is only required when changing the address.
Additional Applications
The constant voltage mode feature of the AAT3172 allows the user to combine the flash feature with additional applications. Additional applications such as auxiliary lighting and status LEDs can be added while eliminating the need for an additional power supply, which is normally required. Since the constant voltage mode can supply a regulated output at up to 100mA load, it is capable of driving five LEDs at 20mA each. It is suitable for keypad lighting, status lighting, and other applications where a 4.5V power supply could be used. When enabling constant voltage mode, the LED channels F1 and F2 are automatically disabled so current does not flow through the flash LED during constant voltage mode. Because of this, very little programming is required. The user just addresses the voltage mode register and programs it to voltage mode.
C1 1F
C2 1F
C1+ 2.7V to 5.5V
CIN 4.7F
C1- C2+
C2VOUT
VIN
AAT 3172
COUT 2.2F
Flash LED
EN/SET
EN/SET GND
F1 F2 AUX_EN
Figure 1: Flash Plus Auxiliary Lighting.
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AAT3172
High Current LED Flash Driver Charge Pump IC
C1 1F C2 1F
C1+ 2.7V to 5.5V
CIN 4.7F
C1- C2+
C2VOUT
VIN
AAT 3172
C OUT 2.2F
Flash LED
EN/SET
EN/SET GND
F1 F2
STAT1
STAT2
Figure 2: Flash Plus Status Lighting.
LED Selection
The AAT3172 is designed to drive high intensity white flash LEDs with forward voltages up to 4.4V.
Charge Pump Efficiency
= POUT PIN 1X Mode
(ESR) (<100m) ceramic capacitors are used. A value of 1F for all four capacitors is a good starting point when choosing capacitors. If the LED current sinks are only programmed for light current levels, then the capacitor size may be decreased. Ceramic composition capacitors are highly recommended over all other types of capacitors for use with the AAT3172. 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.
VF = 100% x V IN
VF = 100% x 1.5V 1.5X Mode IN VF = 100% x 2V IN 2X Mode
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.
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
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AAT3172
High Current LED Flash Driver Charge Pump IC
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. Large 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 large capacitors are not required in the AAT3172 application. 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.
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AAT3172
High Current LED Flash Driver Charge Pump IC Ordering Information
Package
TDFN33-12
Marking1
QLXYY
Part Number (Tape and Reel)2
AAT3172IWP-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
TDFN33-12
Index Area (D/2 x E/2) Detail "B"
3.00 0.05
2.40 0.05
0.3 0.10 0.16 0.375 0.125 0.075 0.075 0.1 REF
Detail "A"
Top View
Bottom View
Pin 1 Indicator (optional)
7.5 7.5
+ 0.05 0.8 -0.20
0.229 0.051
Detail "B"
Option A: C0.30 (4x) max Chamfered corner Option B: R0.30 (4x) max Round corner
0.05 0.05
Side View
All dimensions in millimeters.
Detail "A"
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 14
3172.2005.11.1.1
0.23 0.05
0.45 0.05
3.00 0.05
1.70 0.05

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