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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter General Description
The AAT1299 is a high efficiency, synchronous, fixed frequency, step-up converter with start-up inrush current limit and short-circuit protection. The input voltage ranges from 1.0V to the output voltage. The high 2MHz switching frequency and completely integrated control circuitry minimize the total solution footprint area while maintaining excellent regulation, ripple, and transient response throughout the full load range. Light load switching frequency modulation and low quiescent current maintain high efficiency performance for light load and sleep mode conditions. With a 1A peak switch current limit, the AAT1299 is capable of delivering 200mA to the load from a 1.8V input. The AAT1299 is available in a Pb-free, space-saving 2.0x2.1mm 8-pin SC70JW or 2.2x2.2mm 10pin STDFN package, or in die form and is rated over the -40C to +85C temperature range.
Features
* * * * * * * * * * * * * * *
SwitchRegTM
200mA Output from a 1.8V Input VIN Operation Range: 1.0V to VOUT Up to 93% Efficiency Low Start-Up Voltage: 1.0V Typical Internal Synchronous Rectifier Current Mode Control with Internal Feedback and Compensation 2MHz Fixed Switching Frequency 1A Current Limit Maintains High Efficiency Over the Output Current Range for Improved Battery Life Low 40A No Load Bias Current Short-Circuit and Over-Current Protection Inrush Current Limit and Soft Start Low Shutdown Current: <1.0A -40C to +85C Temperature Range 2.0x2.1mm SC70JW-8 or 2.2x2.2mm 10-pin STDFN Package or Die
Applications
* * * * * BluetoothTM Headsets Digital Cameras Medical Instruments Mobile Handsets MP3 and Portable Music Players
Typical Application
VIN 2.2H LX AAT1299 VCC VOUT
VIN
OUT 4.7F
4.7F
EN
GND
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter Pin Descriptions
Pin #
SC70JW-8 STDFN-10
Symbol
VCC EN VIN LX OUT GND N/C
Function
Bias supply voltage after start-up and feedback to the output voltage error amplifier. Enable pin. Logic high enables the IC. Logic low disables the IC and disconnects the load from the input. Shutdown current is <1A. Input voltage. Supplies the IC at start-up. Inductor connection. Ties to the drains of the P-channel synchronous rectifier and the N-channel MOSFET switch. Boost converter output voltage; connects to the P-channel synchronous MOSFET source. Bypass with ceramic capacitor to GND. Signal and power ground. Connect output capacitor return. Not connected. Exposed paddle (bottom). Connect to ground as closely as possible to the device.
1 2 3 4 5 6, 7, 8 N/A N/A
5 4 3 1, 2 9 7 6, 8, 10 EP
Pin Configuration
SC70JW-8 (Top View) STDFN-10 (Top View)
VCC EN VIN LX
1 2 3 4
8 7 6 5
GND GND GND OUT
LX LX VIN EN VCC
1 2 3 4 5
10 8 8 7 6
N/C OUT N/C GND NC
Die Contact your local AnalogicTech Sales representative.
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter Absolute Maximum Ratings1
Symbol
VN VEN TJ TLEAD
Description
VIN, OUT, VCC, LX to GND EN to GND Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec)
Value
-0.3 to 6.0 -0.3 to VIN -40 to 150 300
Units
V V C C
Thermal Characteristics2
Symbol
JA PD
Description
Thermal Resistance Maximum Power Dissipation SC70JW-8 STDFN-10 SC70JW-8 STDFN-10
Value
160 50 625 2
Units
C/W mW W
1. Stresses above those listed in Absolute Maximum Ratings may cause 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 a FR4 board. 1299.2007.06.1.0
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter Electrical Characteristics1
VIN = 1.8V, TA = -40C to +85C, unless otherwise noted. Typical values are TA = 25C. Symbol
VIN VOUT IQ ISHDN RDS(ON)H RDS(ON)L ILIMIT ILL VOUT/VOUT VOUT/VOUT/VIN FOSC DTYMAX VTH(L-IN) VTH(H-IN)
Description
Minimum Start-Up Voltage Operating Input Voltage Range Output Voltage Accuracy Quiescent Supply Current (Light Load Operation)2 Shutdown Current PMOS On-Resistance NMOS On-Resistance NMOS Current Limit Light Load Current Threshold Efficiency Load Regulation Line Regulation Switching Frequency Maximum Duty Cycle Logic Input Low Threshold for EN Logic Input High Threshold for EN
Conditions
ILOAD = 1mA VIN = 1.0V to 2.5V, PWM Mode No Load EN = 0V, VIN = 5.5V TA = 25C TA = 25C
Min
1.0 VOUT 0.1
Typ
1.0
Max
VOUT VOUT + 0.1
Units
V V A A m m A mA % % %/V MHz % V V
40
70 1.0
IOUT = 50mA, L = 2.2H ILOAD = 0 to 100mA VIN = 1.0V to 2.5V TA = 25C
1.8
750 400 1.0 30 85 1.5 0.2 2.0 90
2.2 0.4
1.0
1. The AAT1299 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. IQ = IQ_VOUT = IQ_VCC.
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter Typical Characteristics
Single-Cell to 3.3V Efficiency
100 90 100
Dual-Cell to 3.3V Efficiency
VIN = 3.0V
Efficiency (%)
Efficiency (%)
VIN = 1.5V
90 80
80 70 60 50 0.1
VIN = 2.4V
70 60 50
VIN = 2.0V
VIN = 1.2V
1
10
100
1000
0.1
1
10
100
1000
Output Current (mA)
Output Current (mA)
Single-Cell Load Regulation
(VO = 3.3V)
2.0 1.5 2.0 1.5
Dual-Cell Load Regulation
(VO = 3.3V)
VOUT Error (%)
VOUT Error (%)
1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 0.1 1
1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0
VIN = 3.0V VIN = 2.4V
VIN = 1.5V
VIN = 1.2V
10 100
VIN = 2.0V
0.1 1 10 100 1000
Output Current (mA)
Output Current (mA)
Minimum Start-Up Voltage vs. Load Current
2.4 120
Light Load Mode Output Current Threshold vs. Input Voltage
Output Current (mA)
100 80 60 40 20 0
2.2 2.0
Constant Current Load
Increasing Load
Voltage (V)
1.8 1.6 1.4 1.2 1.0 0.8 0 2 40 60 80 100 120 140 160
Resistive Load
Decreasing Load
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
Current (mA)
Input Voltage (V)
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter Typical Characteristics
No Load Input Current vs. Input Voltage
200
Switching Frequency vs. Temperature
Switching Frequency Change (%)
0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 -40
Input Current (A)
160 120 80 40 0 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
-15
10
35
60
85
Input Voltage (V)
Temperature (C)
Maximum Load Current Capacity for a 4% Drop in Output Voltage vs. Input Voltage
(VOUT = 3.3V)
600
Load Transient Response
(VIN = 1.2V; L = 2.2H; CO = 4.7F)
3.40
Load Current (mA)
500 400 300 200 100 0 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
Output Current (A)
3.35 3.30 3.25 3.20 0.15 0.10 0.05 0.00 50mA 100mA
Output Voltage (V)
Input Voltage (V)
Time (50s/div)
Output Voltage vs. Temperature
(VIN = 1.5V; IO = 10mA)
0.40
Line Transient Response
(IO = 50mA; L = 2.2H; CO = 4.7F)
2.50 2.4V
Output Voltage Error (%)
0.20
Output Voltage (V)
2.25
Input Voltage (V)
0.00 -0.20 -0.40 -0.60 -0.80 -40
2.00 1.9V 3.34 3.32 3.30 3.28 3.26 1.75 1.50
-20
0
20
40
60
80
Temperature (C)
Time (50s/div)
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter Typical Characteristics
Soft-Start Inrush Current
(VIN = 1.2V; IO = 40mA; VO = 3.3V)
Soft-Start Inrush Current
(VIN = 2.4V; IO = 100mA; VO = 3.3V)
1.75
Enable and Output Voltage (V)
4 3 2 1 0 -1 -2 -3 -4
Enable and Output Voltage (V)
4 3 2 1 0 -1 -2 -3 -4
1.75
Output Voltage
1.5
Output Voltage
1.5
Input Current (A)
Input Current (A)
1.25
1.25 1
Enable
1 0.75 0.5
Enable
0.75 0.5 0.25
Input Current
0.25 0 -0.25
Input Current Time (500s/div)
0 -0.25
Time (500s/div)
Full Load Output Ripple
(VIN = 1.2V; 100mA Load) VOUT (AC Coupled) (20mV/div) IL (100mA/div) VLX (2V/div) VOUT (AC Coupled) (20mV/div) IL (200mA/div) VLX (2V/div)
Light Load Output Ripple
(VIN = 1.2V; 10mA Load)
Time (250ns/div)
Time (1s/div)
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter Functional Block Diagram
VCC VIN OUT
Start-Up Inrush Control VREF
Low Voltage Start-Up
Voltage Reference
Mode Control
DH
2MHz Oscillator
Logic
LX
Current Sense
Comp.
DL
Error Amp.
GND
EN
GND
Functional Description
The AAT1299 synchronous step-up converter is targeted for single- or dual-cell alkaline, NiMH, and NiCd battery applications. It has a 1V typical startup voltage. The high 2MHz switching frequency of the AAT1299 facilitates output filter component size reduction for improved power density and reduced overall footprint. It also provides greater bandwidth and improved transient response over other lower
frequency step-up converters. The compensation and feedback is integrated with only three external components (CIN, COUT, L). Low RDS(ON) synchronous power switches provide high efficiency for heavy load conditions. Switching frequency modulation and low quiescent current maintains this high efficiency for light load and sleep mode conditions. In addition to the improved efficiency, the synchronous boost has the added performance advantage of inrush current limit and short-circuit protection.
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter
PWM / Light Load Control
The AAT1299 is a fixed frequency PWM peak current mode control step-up converter. For light load conditions (10 to 20mA and below), the converter transitions to a light load mode to reduce the dominant switching losses. In addition to light load operation, a zero current comparator blocks reverse current in the P-channel synchronous MOSFET, forcing DCM operation at light load. These controls, along with very low quiescent current, help to maintain high efficiency over the complete load range without the compromise of increased output voltage ripple during light load conditions.
Applications Information
Inductor Selection
The AAT1299 is designed to operate with a 2.2H inductor for all input/output voltage combinations. The inductor saturation current rating should be greater than the NMOS current limit specification listed in the Electrical Characteristics table. If necessary, the peak inductor current can exceed the saturation level by a small amount with no significant effect on performance. Table 1 provides a list of some suggested inductor manufacturers and their part numbers.
Start-up and Inrush Current Limit
The start-up sequence of the AAT1299 varies depending upon whether the input voltage is greater than or less than 2V. Above 1V, a start-up oscillator operating at 25% duty cycle controls the synchronous power stage and charges the output to 2V. For an input voltage greater than 2V, the output is charged at a constant current of 300mA until the output reaches a voltage level just below the input voltage. The step-up converter then takes control and continues to charge the output to the steady-state voltage. The step-up converter Nchannel switch current is limited to 1A and the typical start-up time is 2.5ms.
Output and Input Capacitor Selection
Surface mount X5R or X7R ceramic capacitors are suggested for both the output and the input. For the output capacitor (C1 in Figure 4) a 4.7F, 10V, X5R ceramic capacitor is necessary for stability, transient response, and ripple performance. The same 0805 sized capacitor is used for the input (C2 of Figure 4). If desired, a smaller, 0603 sized, 4.7F, 6.3V, X5R ceramic capacitor can be substituted for the input capacitor (C2). Suggested ceramic capacitor suppliers are listed in Table 1.
PCB Layout Guidelines
Figures 1, 2, and 3 display the evaluation board layout and suggested component placement. Due to the high switching speed of the AAT1299, it is important that the evaluation board layout be followed. Even the best switch-mode power supply design cannot overcome the problems that can be caused by a poor layout. For the AAT1299, it is necessary that C1 and C2 be placed as close as possible to the IC with a good low impedance path to the GND pins of the IC. It is also good practice to minimize the length of the trace from the OUT pin to the output inductor. This prevents switching noise from radiating into other high noise sensitive, high impedance circuits.
Short-Circuit Protection
The P-channel synchronous MOSFET body diode gives the AAT1299 the ability to provide output short-circuit current limit protection.
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter
Figure 1: AAT1299 Evaluation Board Top Side.
Figure 2: Component Placement.
Figure 3: AAT1299 Evaluation Board Bottom Side.
VIN U1 AAT1299
1 1 2 3 2 3 4
VCC GND EN VIN LX GND GND OUT
8 7 6
Enable L1 2.2H C2 4.7F
VOUT
5
C1 4.7F
U1 AAT1299 SC70JW-8 L1 SD3118-2R2 C1, C2 4.7F 10V 0805 X5R
Figure 4: AAT1299 Evaluation Board Schematic.
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter
Manufacturer
Murata www.murata.com TDK www.tdk.com Taiyo Yuden www.t-yuden.com
Value
4.7F 4.7F 4.7F
Part
Output or Input Capacitor Input Capacitor Output or Input Capacitor Input Capacitor Output or Input Capacitor Input Capacitor
Voltage
10V 6.3V 10V 6.3V 10V 6.3V
Case Size
0805 0603 0805 0603 0805 0603
Part Number
GRM21BR61A475KA73L GRM188R60J475KE19D C2012X5R1A475K C1608X5ROJ475K LMK212BJ475MG JMK107BJ475MA
Manufacturer
Sumida www.sumida.com Cooper Electronics www.cooperet.com
Value
2.2H 2.2H
Part
Inductor Inductor
ISAT
1.50A 1.62A
DCR
75m 69m
Case Size
3.2 x 3.2 x 1.55 3.1 x 3.1 x 1.85
Part Number
CDRH2D14-2R2 SD3118-2R2
Table 1: Suggested Component Selection.
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter Ordering Information
Voltage
3.3V 3.3V 3.3V
Package
SC70JW-8 2.2x2.2mm STDFN-10 Die
Marking1
YRXYY YQXYY AAT1299
Part Number (Tape and Reel)2
AAT1299IJS-3.3-T1 AAT1299IOQ-3.3-T1 AAT1299IZZ-3.3
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 Information3
SC70JW-8
0.50 BSC 0.50 BSC 0.50 BSC
1.75 0.10
0.225 0.075 2.00 0.20
2.20 0.20
0.048REF
0.85 0.15
1.10 MAX
0.15 0.05
0.100
7 3
0.45 0.10 2.10 0.30
4 4
All dimensions in millimeters.
1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection.
0.05 0.05
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter
STDFN-10
Index Area 2.200 0.050 1.000 0.050 Detail "A"
Top View
2.200 0.050
1.710 0.050
Bottom View
0.350 0.050
0.550 0.050
0.025 0.025
0.152 REF
Side View
Pin 1 Indicator (optional) R0.200
Detail "A"
Die Please contact your local AnalogicTech Sales representative.
1299.2007.06.1.0
0.210 0.050
0.400 BSC
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AAT1299
Low Voltage 2MHz Step-Up DC/DC Converter
(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. Except as provided in AnalogicTech's terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer's applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. 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. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737-4600 Fax (408) 737-4611 14
1299.2007.06.1.0

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