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500mA High Efficiency Charge Pump for White LED Flash Applications General Description
The AAT3112 is a member of Analogic TechTM's Power Management ICTM family. It is a dual charge pump voltage doubler that provides a regulated output voltage. It operates with input voltage range of 2.7 - 5.0 Volts. The device can deliver up to 500 mA of pulsed current making it ideal for white LED flash applications. Low external parts counts (two 1F flying capacitors and two small capacitors at VIN and VOUT) make AAT3112 ideally suited for small battery powered applications. The AAT3112 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 startup. A high charge pump switching frequency enables the use of very small external capacitors. A low current shutdown feature disconnects the load from VIN and reduces quiescent current to less than 1A. The AAT3112 is available in 16 pin 3x3mm QFN package.
AAT3112
Features
* * * * * * * * * *
ChargePumpTM
VIN Range: 2.7V to 5.5V IQ < 1A in Shutdown Up to 500mA of output current Regulated 4.5V output 26A of Quiescent Current Small Application Circuit Automatic Soft-Start No Inductors Short circuit/over temperature protection 16 pin 3x3 QFN package
Preliminary Information
Applications
* * White LED Backlighting White Photo-Flash
Typical Application
C1= 1F C1= 1F
C1+
C1-
C2 +
C2 VOUT
VIN
CIN
VIN
VOUT
C OUT
AAT3112
D1
Enable Light EN1
D2
D3
D4
Enable Flash
EN2 GND
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500mA High Efficiency Charge Pump for White LED Flash Applications Pin Descriptions
Pin #
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
AAT3112
Symbol
N/C C2+ C2N/C VIN GND EN2 N/C EN1 GND VIN VOUT1 N/C C1+ C1VOUT2
Function
No connect. Flying Capacitor 2 positive terminal. Connect 1F Capacitor between C2+ and C2-. Flying Capacitor 2 negative terminal. No connect. Input Voltage. Connect to pin 11. Ground connection Enable pin. When connected high, charge pump 2 is enabled. When connected low, it disables the charge pump. No connect. Enable pin. When connected high, charge pump 1 is enabled. When connected low, it disables the charge pump. Ground connection Input Voltage. Connect to pin 5. Output pin for regulated output Voltage. Bypass this pin to ground with a low ESR capacitor. No connect. Flying Capacitor 1 positive terminal. Connect 1 F Capacitor between C1+ and C1-. Flying Capacitor 1 negative terminal. Regulated output Voltage 2. Must be connected to VOUT1 for higher current applications. If used separately, bypass this pin to ground with a low ESR capacitor.
Pin Configuration
QFN33-16 (Top View) N/C C1+ C1VOUT2
16 15 14 13
N/C C2+ C2N/C
1 2 3 4 5 6 7 8
12 11 10 9
VOUT1 VIN GND EN1
N/C EN2 GND VIN
2
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500mA High Efficiency Charge Pump for White LED Flash Applications Absolute Maximum Ratings1
Symbol
VIN VOUT VEN TJ TLEAD
AAT3112
Description
Input Voltage Charge Pump Output EN to GND Voltage Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec)
Value
-0.3 to 6 -0.3 to 6 -0.3 to 6 -40 to 150 300
Units
V V V C C
Note 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.
Thermal Information
Symbol
PD JA
Description
Maximum Power Dissipation Maximum Thermal Resistance1
Value
2.0 50
Units
W C/W
Note 1: Mounted on an FR4 board.
Electrical Characteristics
VIN = 3.3V, VOUT = 5.0V, CIN = COUT = 10 F, C1 = C2 = 1.0F; TA = -40 to 85 C. Unless otherwise noted, typical values are TA = 25C Symbol Description Conditions Min
2.7 2.7 VIN 5.0, IOUT = 0 mA; EN1 = EN2 = VIN EN1 = EN2 = 0 VIN = 3.6V; VOUT = 4.0V; TPULSE = 50mS VIN = 3.6V; VOUT =4.0V; TPULSE = 500mS 2.7 VIN 5.0, IOUT = 100mA 3.0 VIN 5.0, IOUT = 200mA 26 590 500 4.5 4.5 750 80 0.3 1.4 -1.0 1.0
Typ Max Units
5.5 60 1.0 V A A mA 4.68 4.68 V
Input Power Supply VIN Operation Range IQ Quiescent Current ISHDN Shutdown Current Pulsed Output Current IOUT VOUT Charge Pump FCLK CP EN VEN(L) VEN(H) IEN Output Voltage Section Clock Frequency Charge Pump Efficiency Enable Threshold Low Enable Threshold High EN Input leakage
4.32 4.32
VIN = 2.7V; IOUT = 100mA
KHz % V V A
Note 1: The AAT3112 is guaranteed to meet performance specification over the -40 to +85C operating temperature range, and are assured by design, characterization and correlation with statistical process controls.
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500mA High Efficiency Charge Pump for White LED Flash Applications Typical Characteristics
(unless otherwise noted: VIN=3.5V, CIN=COUT=10F, C1=C2=1F, TA=25C) Output Voltage vs. Output Current
5.0 30
AAT3112
Supply Current vs. Supply Voltage No load, No switching
Supply Current (A)
25 20 15 10 5 0
4.9
Output Voltage (V)
4.8 4.7 4.6 4.5 4.4 4.3 4.2 4.1 4.0 0
VIN = 3.6V
VIN = 3.9V
VIN = 4.2V
50
100
150
200
250
300
2.5
3.0
3.5
4.0
4.5
Output Current (mA)
Supply Voltage (V)
Startup Time with 100mA Load
Startup Time with 200mA Load
EN (2V/div)
EN (2V/div)
VOUT (1V/div) 50s/div
VOUT (1V/div) 50s/div
Maximum Current Pulse (50ms pulse) vs. Input Voltage, VOUT > 4.0V
Maximum Current Pulse (mA)
800 700 600 500 400 300 3 3.2 3.4 3.6 3.8 4 4.2
Efficiency vs. Supply Voltage
85% 80%
50mA
Efficiency (%)
75% 70% 65% 60% 55% 50% 45% 40% 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9
200mA 100mA
Input Voltage (V)
Input Voltage (V)
4
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500mA High Efficiency Charge Pump for White LED Flash Applications Typical Characteristics
(unless otherwise noted: VIN=3.5V, CIN=COUT=10F, C1=C2=1F, TA=25C) Load Transient Response (VIN = 3.0V) Load Transient Response (VIN = 4.2V)
AAT3112
IOUT (200mA/div)
IOUT (200mA/div)
VOUT (20mV/div)
VOUT (20mV/div)
Time (50s/div)
Time (50s/div)
Output Current vs. Input Voltage 500ms Pulse Time, VOUT > 4.0V
800 800
Output Current vs. Input Voltage (70C) VOUT > 4.0V
Output Current (mA)
700 600 500 400 200ms 300ms 300 200 100 0 500ms 50ms 100ms
Output Current (mA)
700 600 500 400 300 200 100 0 2.5 3 3.5 4 4.5
2.5
3
3.5
4
4.5
Input Voltage (V)
Input Voltage (V)
Output Voltage vs. Input Voltage for Pulsed High-Current, IOUT = 500mA
5 4.5
50ms Pulse 500ms Pulse
Output Voltage (V)
4 3.5 3 2.5 2 1.5 1 0.5 0 3 3.2 3.4 3.6 3.8 4 4.2
Input Voltage (V)
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500mA High Efficiency Charge Pump for White LED Flash Applications Typical Characteristics
(unless otherwise noted: VIN=3.5V, CIN=COUT=10F, C1=C2=1F, TA=25C) VIN vs. VIH
1.00 0.95 0.90 0.85 1.00
AAT3112
VIN vs. VIL
0.95 0.90
-40C 25C VIL (V)
0.85 0.80 0.75 0.70 0.65 0.60 0.55
-40C 25C
VIH (V)
0.80 0.75 0.70 0.65 0.60 0.55 0.50 2.0
85C
85C
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0.50 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VIN (V)
VIN (V)
VSHDN Threshold vs. Supply Voltage
1.00 0.95 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VSHDN Threshold (V)
VIH
VIL
VIN (V)
6
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500mA High Efficiency Charge Pump for White LED Flash Applications Functional Block Diagram
EN1 V IN
S2 S1
AAT3112
C1 +
Control Circuit
S4 S3
C1 -
+ -
VOUT1
EN2
Control Circuit
VREF
+
GND
S1
S2
C2+ C2S3 S4
V OUT2
Functional Description
The AAT3112 is a dual charge pump intended for high current applications. It boosts the input voltage to a regulated output voltage. Regulation is achieved by sensing the output voltage through an internal resistor divider network. The AAT3112 requires only four external components: two 1.0F ceramic capacitors for the charge pump (C1 and C2), one 10F ceramic capacitor for CIN and one 10F ceramic capacitor for COUT.
The AAT3112 is designed to deliver 200 mA of continuous current, and up to 500 mA of pulsed current. Each charge pump engine has an independent enable pin for longer battery life. The charge pump switching frequency is approximately 750 KHz enabling the use of small external flying capacitors. The AAT3112 has complete output short circuit and thermal protection to safeguard the device under extreme operating conditions. An internal thermal protection circuit senses die temperature and will shut down the device if the internal junction temperature exceeds approximately 145C.
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500mA High Efficiency Charge Pump for White LED Flash Applications Applications Information
Charge Pump Efficiency
The AAT3112 is a regulated output voltage doubling charge pump. The efficiency () can simply be defined as a linear voltage regulator with an effective output voltage that is equal to two times the input voltage. Efficiency () for an ideal voltage doubler can typically be expressed as the output power divided by the input power: = POUT PIN
AAT3112
Capacitor Characteristics
Ceramic composition capacitors are highly recommended over all other types of capacitors for use with the AAT3112. 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): ESR is an important characteristic to consider when selecting a capacitor. ESR is a resistance internal to a capacitor, which 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 0.1F are typically made from NPO or COG materials. NPO and COG 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 low cost Y5V and Z5U dielectrics, but large capacitors are not required in the AAT3112 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.
In addition, with an ideal voltage doubling charge pump, the output current may be expressed as half the input current. The expression to define the ideal efficiency () can be rewritten as: = POUT VOUT x IOUT VOUT = = PIN VIN x 2IOUT 2VIN VOUT 2VIN
(%) = 100
For a charge pump with an output of 5 volts and a nominal input of 3.0 volts, the theoretical efficiency is 83.3%. Due to internal switching losses and IC quiescent current consumption, the actual efficiency can be measured at 82.7%. These figures are in close agreement for output load conditions from 1mA to 400mA. Efficiency will decrease as load current drops below 0.05mA or when the level of VIN approaches VOUT.
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 ESR (<100m) ceramic capacitors are used. In general, low ESR may be defined as less than 100m.
Layout Considerations
High charge pump switching frequencies and large peak transient currents mandate careful printed circuit board layout. As a general rule for charge pump boost converters, all external capacitors should be located as close as possible to the device package with minimum length trace connections. Maximize the ground plane around the AAT3112 charge pump and make sure all external capacitors are connected to the immediate ground plane. A local component side ground plane is recommended.
8
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500mA High Efficiency Charge Pump for White LED Flash Applications Application Circuits
C1= 1F C1= 1F
AAT3112
C1+ C1 - C2 + VIN CIN=10F VIN
C2 VOUT COUT=10F VOUT
EN1 EN2 D1 GND R2=10 D1 LL4148 R1 TPULSE 2K C5 0.1F Q1 AAT9513 D2 D3 D4
Figure 1: Flash Application
C1= 1F
C1= 1F
C1+ C1 - C2 + V IN CIN=10F VIN
C2 VOUT COUT=10F VOUT
EN1 EN2 D1 GND R3=60 - 100 R2=10 D2 D3 D4
D1 LL4148 R1 TPULSE 2K C5 0.1F Q1 AAT9513
Figure 2: Movie Mode Light 9
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500mA High Efficiency Charge Pump for White LED Flash Applications Ordering Information
Package QFN33-16 QFN33-16 Marking1 LGXYY MNXYY Part Number (Tape and Reel) AAT3112IVN-4.5-T1 AAT3112IVN-5.0-T1
AAT3112
Note: Sample stock is held on part numbers listed in bold. Note 1: XYY = assembly and date code.
Package Information
QFN33-16
Pin 1 Identification
1
0.240 0.060
5
3.000 0.050
Pin 1 Dot By Marking
0.400 0.100
13 9
3.000 0.050
0.500 0.050
Top View
Bottom View
0.975 0.725 0.025 0.025 0.213 0.036
Side View
All dimensions in millimeters.
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 10
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