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300mA MicroPowerTM High Performance LDO General Description
The AAT3238 MicroPowerTM Low Dropout Linear Regulator is ideally suited for portable applications where very fast transient response, extended battery life and small size are critical. The AAT3238 has been specifically designed for high speed turn on and turn off performance, fast transient response, good power supply ripple rejection (PSRR) and is reasonably low noise, making it ideal for powering sensitive circuits with fast switching requirements. Other features include low quiescent current, typically 70A, and low dropout voltage which is typically less than 400mV at the maximum output current level of 300mA. The device is output short circuit protected and has a thermal shutdown circuit for additional protection under extreme operating conditions. The AAT3238 also features a low-power shutdown mode for extended battery life. A reference bypass pin has been provided to improve PSRR performance and output noise, by connecting a small external capacitor from the AAT3238's reference output to ground. The AAT3238 is available in a space saving 6-pin SOT23 or 8-pin SC70JW package in factory programmed voltages.
AAT3238
Features
* * * * * * * * * * * * * * * *
PowerLinearTM
Low Dropout - 400mV at 300mA Guaranteed 300mA Output High accuracy 1.5% 70A Quiescent Current Fast line and load transient response High speed device turn-on and shutdown High Power Supply Ripple Rejection Low self noise Short circuit protection Over-Temperature protection Uses Low ESR ceramic capacitors Noise reduction bypass capacitor Shutdown mode for longer battery life Low temperature coefficient Factory programmed output voltages SOT23 6-pin or SC70JW 8-pin package
Applications
* * * * * Cellular Phones Notebook Computers Portable Communication Devices Personal Portable Electronics Digital Cameras
Typical Application
VIN IN OUT VOUT
AAT3238
ON/OFF 1F EN GND 10nF 2.2F BYP
GND
GND
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300mA MicroPowerTM High Performance LDO Pin Descriptions
Pin #
SOT23-6 SC70JW-8
AAT3238
Symbol
IN GND EN
Function
Input voltage pin - should be decoupled with 1F or greater capacitor. Ground connection pin Enable pin - this pin should not be left floating. When pulled low the PMOS pass transistor turns off and all internal circuitry enters low-power mode, consuming less than 1A. Bypass capacitor connection - to improve AC ripple rejection, connect a 10nF capacitor to GND. This will also provide a soft start function. Output pin - should be decoupled with 2.2F ceramic capacitor.
1 2, 5 3
5, 6 8 7
4
1
BYP
6
2, 3, 4
OUT
Pin Configuration
SOT23-6 (Top View) SC70JW-8 (Top View)
IN GND EN
1
6
OUT GND BYP
2
5
3
4
BYP OUT OUT OUT
1 2 3 4
8 7 6 5
GND EN IN IN
2
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300mA MicroPowerTM High Performance LDO Absolute Maximum Ratings
Symbol
VIN VENIN(MAX) IOUT TJ
AAT3238
(TA=25C unless otherwise noted) Value
6 0.3 PD/(VIN-VO) -40 to 150
Description
Input Voltage Maximum EN to Input Voltage DC Output Current Operating Junction Temperature Range
Units
V V mA C
Note: 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
JA PD
Description
Maximum Thermal Resistance (SOT23-6, SC70JW-8) Maximum Power Dissipation1 (SOT23-6, SC70JW-8)
1
Rating
150 667
Units
C/W mW
Note 1: Mounted on a demo board.
Recommended Operating Conditions
Symbol
VIN T
Description
Input Voltage Ambient Temperature Range
2
Rating
(VOUT+VDO) to 5.5 -40 to +85
Units
V C
Note 2: To calculate minimum input voltage, use the following equation: VIN(MIN) = VOUT(MAX) + VDO(MAX) as long as VIN 2.5V.
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300mA MicroPowerTM High Performance LDO Electrical Characteristics
(VIN=VOUT(NOM)+1V for VOUT options greater than 1.5V. VIN= 2.5 for VOUT1.5V. IOUT=1mA, COUT=2.2F, CIN=1f, TA= -40 to 85C unless otherwise noted. Typical values are TA=25C) Symbol
VOUT IOUT VDO ISC IQ ISD VOUT/ VOUT*VIN VOUT(line) VOUT(load) tENDLY VEN(L) VEN(H) IEN PSRR TSD THYS eN TC
AAT3238
Description
Output Voltage Tolerance Output Current Dropout Voltage 1, 2 Short Circuit Current Ground Current Shutdown Current Line Regulation Dynamic Line Regulation Dynamic Load Regulation Enable Delay Time Enable Threshold Low Enable Threshold High Leakage Current on Enable Pin Power Supply Rejection Ratio
Conditions
IOUT = 1mA to 300mA
Min Typ Max
TA=25C -1.5 TA=-40 to 85C -2.5 300 400 600 70 1.5 2.5 600 125 1 0.09 2.5 60 15 0.6 1.5
Units
% % mA mV mA A A %/V mV mV s V V A dB C C Vrms/rtHz ppm/C
VOUT > 1.2V IOUT = 300mA VOUT < 0.4V VIN = 5V, No load, EN = VIN VIN = 5V, EN = 0V VIN = VOUT + 1 to 5.0V
VIN=VOUT+1V to VOUT+2V, IOUT=300mA, TR/TF =2s IOUT = 1mA to 300mA, TR<5s BYP = open
VEN = 5V 1 kHz IOUT=10mA, CBYP=10nF 10kHz 1MHz 67 47 45 145 12 50 22
1
Over Temp Shutdown Threshold Over Temp Shutdown Hysteresis Output Noise Noise Power BW = 300Hz-50kHz Output Voltage Temp. Coeff.
Note 1: VDO is defined as VIN - VOUT when VOUT is 98% of nominal. Note 2: For VOUT < 2.1V, VDO = 2.5V - VOUT.
4
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300mA MicroPowerTM High Performance LDO Typical Characteristics
AAT3238
(Unless otherwise noted, VIN = 5V, TA = 25C) Dropout Voltage vs. Temperature
540
3.20
Dropout Characteristics
Dropout Voltage (mV)
480 420
IL = 300mA
3.00 2.80
IOUT = 0mA
300 240 180 120 60 0
IL = 150mA
IL = 100mA
V OUT (V)
360
2.60 2.40 2.20 2.00 2.70
IOUT = 300mA IOUT = 150mA IOUT = 10mA
2.80
IL = 50mA
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
IOUT = 100mA IOUT = 50mA
2.90
3.00
3.10
3.20
3.30
Temperature (C)
VIN (V)
Dropout Voltage vs. Output Current
500 450 90.00 80.00 70.00 60.00
Ground Current vs. Input Voltage
Dropout Voltage (mV)
400 350
IGND (A)
300 250 200 150 100 50 0 0 50
85C 25C -40C
50.00 40.00 30.00 20.00 10.00
IOUT=300mA IOUT=0mA IOUT=150mA IOUT=50mA
IOUT=10mA
100
150
200
250
300
0.00 2 2.5 3 3.5 4 4.5 5
Output Current (mA)
VIN (V)
Quiescent Current vs. Temperature
100
Output Voltage vs. Temperature
1.203 1.202
Quiescent Current (A)
90 70 60 50 40 30 20 10 0 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
Output Voltage (V)
80
1.201 1.200 1.199 1.198 1.197 1.196 -40 -30 -20 -10
0
10 20
30
40
50 60
70 80
90 100
Temperature (C)
Temperature (C)
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300mA MicroPowerTM High Performance LDO Typical Characteristics
AAT3238
(Unless otherwise noted, VIN = 5V, TA = 25C) Initial Power Up Response Time CBYP=10nF
VEN (5V/div) VEN (5V/div)
Turn-OFF Response Time CBYP=10nF
VOUT (1V/div)
400s/div
VOUT (1V/div)
50 s/div
Turn-ON Time From Enable (VIN present) CBYP = 10nF
6
Line Transient Response
3.04 3.03 3.02 3.01 3.00
VEN = 5V/div
5 4 3 2
VIN
V IN (V)
VOUT VOUT = 1V/div 5 s/div VIN = 4V
1 0 2.99 2.98
100s/div
Load Transient Response
2.90 2.85 2.80 500 3.00
Load Transient Response 300mA
800 700
VOUT
400 300 200 100 0
2.90 2.80
VOUT (V)
2.70
VOUT
600 500
2.75 2.70 2.65
VOUT (V)
I OUT (mA)
IOUT (mA)
2.60 2.50 2.40 2.30 2.20 2.10
400 300 200
IOUT
2.60 -100
IOUT
100 0 -100
100S/div
10 s/div
6
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300mA MicroPowerTM High Performance LDO Typical Characteristics
AAT3238
(Unless otherwise noted, VIN = 5V, TA = 25C) AAT3238 Self Noise COUT = 10F (ceramic)
Noise Amplitude (V/rtHz)
10 800 1 0.1 Band Power: 300Hz to 50kHz = 44.6Vrms/rtHz 100Hz to 100kHz = 56.3Vrms/rtHz 0.1 1 10 100 1000 10000
Over Current Protection
1200 1000
IOUT (mA)
600 400 200 0 -200
0.01 0.001 0.01
Time (20 ms/div)
Frequency (kHz)
VIH and V IL vs. VIN
1.250 1.225 1.200 1.175 1.150 1.125 1.100 1.075 1.050 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VIH
VIL
VIN (V)
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300mA MicroPowerTM High Performance LDO Functional Block Diagram
IN
Active Feedback Control Over-Current Protection OverTemperature Protection + Error Amplifier -
AAT3238
OUT
EN
Fast Start Control
Voltage Reference
BYP
GND
Functional Description
The AAT3238 is intended for LDO regulator applications where output current load requirements range from no load to 300mA. The advanced circuit design of the AAT3238 has been specifically optimized for very fast start-up and shutdown timing. This proprietary CMOS LDO has also been tailored for superior transient response characteristics. These traits are particularly important for applications, which require fast power supply timing, such as GSM cellular telephone handsets. The high-speed turn-on capability of the AAT3238 is enabled through the implementation of a fast start control circuit, which accelerates the power up behavior of fundamental control and feedback circuits within the LDO regulator. Fast turn-off time response is achieved by an active output pull down circuit, which is enabled when the LDO regulator is placed in the shutdown mode. This active fast shutdown circuit has no adverse effect on normal device operation. The AAT3238 has very fast transient response characteristics, which is an important feature for applications where fast line and load transient response is 8
required. This rapid transient response behavior is accomplished through the implementation of an active error amplifier feedback control. This proprietary circuit design is unique to this MicroPowerTM LDO regulator. The LDO regulator output has been specifically optimized to function with low cost, low ESR ceramic capacitors. However, the design will allow for operation over a wide range of capacitor types. A bypass pin has been provided to allow the addition of an optional voltage reference bypass capacitor to reduce output self noise and increase power supply ripple rejection. Device self noise and PSRR will be improved by the addition of a small ceramic capacitor in this pin. However, increased values of CBYPASS may slow down the LDO regulator turn-on time. This LDO regulator has complete short circuit and thermal protection. The integral combination of these two internal protection circuits give the AAT3238 a comprehensive safety system to guard against extreme adverse operating conditions. Device power dissipation is limited to the package type and thermal dissipation properties. Refer to the thermal considerations discussion in the section for details on device operation at maximum output current loads.
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300mA MicroPowerTM High Performance LDO Applications Information
To assure the maximum possible performance is obtained from the AAT3238, please refer to the following application recommendations.
AAT3238
Bypass Capacitor and Low Noise Applications
A bypass capacitor pin is provided to enhance the low noise characteristics of the AAT3238 LDO regulator. The bypass capacitor is not necessary for operation of the AAT3238. However, for best device performance, a small ceramic capacitor should be placed between the Bypass pin (BYP) and the device ground pin (GND). The value of CBYP may range from 470pF to 10nF. For lowest noise and best possible power supply ripple rejection performance a 10nF capacitor should be used. To practically realize the highest power supply ripple rejection and lowest output noise performance, it is critical that the capacitor connection between the BYP pin and GND pin be direct and PCB traces should be as short as possible. Refer to the PCB Layout Recommendations section of this document for examples. There is a relationship between the bypass capacitor value and the LDO regulator turn on time and turn off time. In applications where fast device turn on time and turn off time is desired, the value of CBYP should be reduced. In applications where low noise performance and/ or ripple rejection are less of a concern, the bypass capacitor may be omitted. The fastest device turn on time will be realized when no bypass capacitor is used. DC leakage on this pin can affect the LDO regulator output noise and voltage regulation performance. For this reason, the use of a low leakage, high quality ceramic (NPO or COG type) or film capacitor is highly recommended.
Input Capacitor
Typically a 1F or larger capacitor is recommended for CIN in most applications. A CIN capacitor is not required for basic LDO regulator operation. However, if the AAT3238 is physically located more than 3 centimeters from an input power source, a CIN capacitor will be needed for stable operation. CIN should be located as close to the device VIN pin as practically possible. CIN values greater than 1F will offer superior input line transient response and will assist in maximizing the highest possible power supply ripple rejection. Ceramic, tantalum or aluminum electrolytic capacitors may be selected for CIN. There is no specific capacitor ESR requirement for CIN. However, for 300mA LDO regulator output operation, ceramic capacitors are recommended for CIN due to their inherent capability over tantalum capacitors to withstand input current surges from low impedance sources such as batteries in portable devices.
Output Capacitor
For proper load voltage regulation and operational stability, a capacitor is required between pins VOUT and GND. The COUT capacitor connection to the LDO regulator ground pin should be made as direct as practically possible for maximum device performance. The AAT3238 has been specifically designed to function with very low ESR ceramic capacitors. For best performance, ceramic capacitors are recommended. Typical output capacitor values for maximum output current conditions range from 1F to 10F. Applications utilizing the exceptionally low output noise and optimum power supply ripple rejection characteristics of the AAT3238 should use 2.2F or greater for COUT. If desired, COUT may be increased without limit. In low output current applications where output load is less then 10mA, the minimum value for COUT can be as low as 0.47F.
Capacitor Characteristics
Ceramic composition capacitors are highly recommended over all other types of capacitors for use with the AAT3238. Ceramic capacitors offer many advantages over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically has very low ESR, is lower cost, has a smaller PCB footprint and is non-polarized. Line and load transient response of the LDO regulator is improved by using low ESR ceramic capacitors. Since ceramic capacitors are non-polarized, they are not prone to incorrect connection damage.
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300mA MicroPowerTM High Performance LDO Applications Information
Equivalent Series Resistance (ESR): ESR is a very important characteristic to consider when selecting a capacitor. ESR is the internal series resistance associated with a capacitor, which includes lead resistance, internal connections, size and area, material composition and ambient temperature. Typically capacitor ESR is 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 are typically tight tolerance very stable over temperature. Larger capacitor values are typically composed of X7R, X5R, Z5U and Y5V dielectric materials. Large ceramic capacitors, typically greater then 2.2F are often available in the low cost Y5V and Z5U dielectrics. These two material types are not recommended for use with LDO regulators since the capacitor tolerance can vary more than 50% over the operating temperature range of the device. A 2.2F Y5V capacitor could be reduced to 1F over temperature, this could cause problems for circuit operation. X7R and X5R dielectrics are much more desirable. The temperature tolerance of X7R dielectric is better than 15%. Capacitor area is another contributor to ESR. Capacitors which are physically large in size will have a lower ESR when compared to a smaller sized capacitor of an equivalent material and capacitance value. These larger devices can improve circuit transient response when compared to an equal value capacitor in a smaller package size. Consult capacitor vendor data sheets carefully when selecting capacitors for LDO regulators. When the LDO regulator is in the shutdown mode, an internal 1.5k resistor is connected between VOUT and GND. This is intended to discharge COUT when the LDO regulator is disabled. The internal 1.5k has no adverse effect on device turn on time.
AAT3238
Short Circuit Protection
The AAT3238 contains an internal short circuit protection circuit that will trigger when the output load current exceeds the internal threshold limit. Under short circuit conditions the output of the LDO regulator will be current limited until the short circuit condition is removed from the output or LDO regulator package power dissipation exceeds the device thermal limit.
Thermal Protection
The AAT3238 has an internal thermal protection circuit which will turn on when the device die temperature exceeds 145C. The internal thermal protection circuit will actively turn off the LDO regulator output pass device to prevent the possibility of over temperature damage. The LDO regulator output will remain in a shutdown state until the internal die temperature falls back below the 145C trip point. The combination and interaction between the short circuit and thermal protection systems allow the LDO regulator to withstand indefinite short circuit conditions without sustaining permanent damage.
No-Load Stability
The AAT3238 is designed to maintain output voltage regulation and stability under operational noload conditions. This is an important characteristic for applications where the output current may drop to zero.
Reverse Output to Input Voltage Conditions and Protection
Under normal operating conditions a parasitic diode exists between the output and input of the LDO regulator. The input voltage should always remain greater then the output load voltage maintaining a reverse bias on the internal parasitic diode. Conditions where VOUT might exceed VIN should be avoided since this would forward bias the internal parasitic diode and allow excessive current flow into the VOUT pin possibly damaging the LDO regulator.
Enable Function
The AAT3238 features an LDO regulator enable/ disable function. This pin (EN) is active high and is compatible with CMOS logic. To assure the LDO regulator will switch on, the EN turn on control level must be greater than 1.5 volts. The LDO regulator will go into the disable shutdown mode when the voltage on the EN pin falls below 0.6 volts. If the enable function is not needed in a specific application, it may be tied to VIN to keep the LDO regulator in a continuously on state. 10
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300mA MicroPowerTM High Performance LDO Applications Information
In applications where there is a possibility of VOUT exceeding VIN for brief amounts of time during normal operation, the use of a larger value CIN capacitor is highly recommended. A larger value of CIN with respect to COUT will effect a slower CIN decay rate during shutdown, thus preventing VOUT from exceeding VIN. In applications where there is a greater danger of VOUT exceeding VIN for extended periods of time, it is recommended to place a Schottky diode across VIN to VOUT (connecting the cathode to VIN and anode to VOUT). The Schottky diode forward voltage should be less than 0.45 volts.
AAT3238
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300mA MicroPowerTM High Performance LDO Ordering Information
Output Voltage 1.2V 1.5V 1.6V 1.8V 1.85V 2.0V 2.3V 2.5V 2.7V 2.8V 2.85 3.0V 3.3V 3.5V 1.2V 1.45V 1.5V 1.8V 2.0V 2.3V 2.5V 2.7V 2.8V 2.85 3.0V 3.3V 3.5V Package SOT23-6 SOT23-6 SOT23-6 SOT23-6 SOT23-6 SOT23-6 SOT23-6 SOT23-6 SOT23-6 SOT23-6 SOT23-6 SOT23-6 SOT23-6 SOT23-6 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 FCXYY KUXYY KIXYY LFXYY JGXYY JRXYY FCXYY KUXYY Marking1 KIXYY JGXYY JSXYY JRXYY JFXYY Part Number (Tape and Reel) AAT3238IGU-1.2-T1 AAT3238IGU-1.5-T1 AAT3238IGU-1.6-T1 AAT3238IGU-1.8-T1 AAT3238IGU-1.85-T1 AAT3238IGU-2.0-T1 AAT3238IGU-2.3-T1 AAT3238IGU-2.5-T1 AAT3238IGU-2.7-T1 AAT3238IGU-2.8-T1 AAT3238IGU-2.85-T1 AAT3238IGU-3.0-T1 AAT3238IGU-3.3-T1 AAT3238IGU-3.5-T1 AAT3238IJS-1.2-T1 AAT3238IJS-1.45-T1 AAT3238IJS-1.5-T1 AAT3238IJS-1.8-T1 AAT3238IJS-2.0-T1 AAT3238IJS-2.3-T1 AAT3238IJS-2.5-T1 AAT3238IJS-2.7-T1 AAT3238IJS-2.8-T1 AAT3238IJS-2.85-T1 AAT3238IJS-3.0-T1 AAT3238IJS-3.3-T1 AAT3238IJS-3.5-T1
AAT3238
Note: Sample stock is generally held on all part numbers listed in BOLD. Note 1: XYY = assembly and date code.
12
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300mA MicroPowerTM High Performance LDO Package Information
SOT23-6
2.85 0.15 1.90 BSC 0.95 BSC
AAT3238
1.575 0.125
1.10 0.20
2.80 0.20 1.20 0.25
0.075 0.075
0.15 0.07 4 4
GAUGE PLANE
10 5 0.40 0.10 x 6
0.60 REF
0.45 0.15
0.10 BSC
All dimensions in millimeters.
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300mA MicroPowerTM High Performance LDO
SC70JW-8
0.50 BSC 0.50 BSC 0.50 BSC
AAT3238
1.75 0.10 0.225 0.075 2.00 0.20
2.20 0.20
0.048REF 0.15 0.05
0.85 0.15
1.10 MAX
0.100
7 3
0.45 0.10 2.10 0.30
4 4
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 14
0.05 0.05
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