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General Description
TM
AAT3232
300mA CMOS Low Drop Out Linear Regulator Features
* * * * * * * * * * * * Low Dropout - 300mV (max) at 300mA Guaranteed 300mA Output High accuracy 30A Quiescent Current Current limit protection Short circuit current fold back Over-Temperature protection Noise reduction bypass capacitor Shutdown mode for longer battery life Low Temperature coefficient 7 Factory programmed output voltages SOT-23 5-pin package
The AAT3232 Low Dropout Linear Regulator is ideal for portable applications where longer battery life is critical. It features low quiescent current (30A typical) and low dropout voltage (300mV max) at full output current. The device is able to protect itself from short circuit conditions with fold back current limiting. Thermal shutdown is activated to prevent damage under extreme conditions. The AAT3232 also features a low-power shutdown mode for longer battery life. A pin is provided to improve PSRR performance, by connecting an external capacitor from the AAT3232's reference output to ground. The AAT3232 is available in a space saving 5-pin SOT-23 in 7 factory programmed voltages of 2.5V, 2.7V, 2.8V, 3.0V, 3.3V, 3.5V and 3.8V.
Preliminary Information
Applications
* * * * Cellular Phones Notebook Computers Portable Communication Devices Handheld Electronics
Typical Application
INPUT V IN ENABLE EN GND
OUTPUT
AAT3232
OUT BYP
CIN
1nF
5.6F ceramic or 10F tantalum
Advanced Analogic Technologies, Inc.
1250 Oakmead Pkwy, Suite 310, Sunnyvale, CA 94086 (408)524-9684 Fax (408)524-9689 1-43
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Symbol
VIN IOUT TJ JA PD TLEAD
TM
AAT3232
300mA CMOS Low Drop Out Linear Regulator
Absolute Maximum Ratings (TA=25C unless otherwise noted)
Description
Input Voltage DC Output Current Operating Junction Temperature Range Thermal Resistance (SOT-23-5) Maximum Power Dissipation (SOT-23-5) Maximum Soldering Temperature (at leads, 10 sec)
Max
8 PD/(VIN-VO) 150 260 380 300
Units
V mA C C/W mW 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.
Recommended Operating Conditions
Symbol
VIN T
Description
Input Voltage Ambient Temperature Range
Rating
(VOUT+0.3) to 7
Units
V C
-40 to +85
Electrical Characteristics (TJ=25C unless otherwise noted)
Symbol VOUT IOUT ISC IQ ISD VOUT/ VOUT VOUT/ VOUT VDO VENL VENH PSRR TSD THYS eN TC Description Output Voltage Output Current Short Circuit Current Ground Current Shutdown Current Line Regulation Load Regulation Dropout Voltage Enable Threshold Low Enable Threshold High Power Supply Rejection Ratio Over Temp Shutdown Threshold Over Temp Shutdown Hysteresis Output Noise Ouput Voltage Temp. Coeff.
1
Conditions VOUT > 1.2V VOUT < 0.4V VIN = 5V, no load VIN = 5V, EN = low IOUT = 5mA, VIN = VOUT + 1 to VOUT + 2 IOUT = 1mA to 300mA IOUT = 300mA
Min -1.5 300
Typ
Max 1.5 300 50 1 0.1 1 300 VIN-0.5
Units % mA mA
30
A A
% % mV V V dB C C
0.02 0.2 200 0.5
1 kHz
55 150 30 20 40
VRMS
ppm/C
Note 1: VDO is defined as VIN - VOUT when VOUT is 98% of nominal.
Advanced Analogic Technologies, Inc.
1250 Oakmead Pkwy, Suite 310, Sunnyvale, CA 94086 (408)524-9684 Fax (408)524-9689 1-44
3232.2000.05.0.98
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Typical Characteristics
TM
AAT3232
300mA CMOS Low Drop Out Linear Regulator
(Unless otherwise noted, VIN = VOUT + 1V, TA = 25C, CNOISE = 10nF, CIN = 2.0F, COUT = 5.6F ceramic, IOUT = 100mA)
Output Voltage vs. Load Current
3.34 3.33 3.32 3.31
40 60
Ground Current vs. Input Voltage
Ta = -40C
50 Ta = +125C
Vout (V)
3.30 3.29 3.28 3.27 3.26 3.25
Ta = +25C
Ignd (A)
30 Ta = +25C 20 Ta = -40C
Ta = +125C
10 0 0 2 4 6 8
Load Current (mA)
0
Step Load Transient Response
Line Voltage (V)
70 60 400 300 200 100 0 -100 -200 -300 -400 0 -500 100 200 300 400 500 600
6 5 4 3 2 1 0 -100
50
100
Iout (mA)
150
200
250
300
Vin (volts)
Line Transient Response
80 60 40 20 0 -20 -40 600
Output Voltage (mV AC coupled)
50 40 30 20 10 0 -10 -20 -200 -100
0
100
200
300
400
500
Time (us)
Time (us)
Advanced Analogic Technologies, Inc.
1250 Oakmead Pkwy, Suite 310, Sunnyvale, CA 94086 (408)524-9684 Fax (408)524-9689 1-45
3232.2000.05.0.98
Output Voltage (mV AC coupled)
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TM
AAT3232
300mA CMOS Low Drop Out Linear Regulator
Power Supply Rejection Ratio
80
Output Noise
10
60 50 40 30 20 10 0 1.E+01 100pF None 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1nF
Noise (uV / Root Hz)
Rejection Ratio (dB)
70
10nF
1 10nF 1nF 0.1 100pF
None
0.01 1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
Frequency (Hz)
Frequency (Hz)
Power-Up, Power-Down Response
6 5 Input
Turn On / Turn Off
12 10 8 6 4 2 0 100pF 4 2 1nF 0 -2 0 2 4 6 8 10 12 14 16 18 10nF -2 -4 -6
Voltage (V)
4 3 2 1 0 -20
Output Voltage (V)
Output
6
-10
0
10
20
30
40
50
60
70
Time (ms)
Time (ms)
Advanced Analogic Technologies, Inc.
1250 Oakmead Pkwy, Suite 310, Sunnyvale, CA 94086 (408)524-9684 Fax (408)524-9689 1-46
3232.2000.05.0.98
Enable (V)
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Pin Descriptions
Pin #
1 2 3 4 5
TM
AAT3232
300mA CMOS Low Drop Out Linear Regulator
Symbol
VIN GND EN BYP OUT
Function
Input voltage pin - should be decoupled with 1F or greater capacitor. Ground connection pin Enable pin - pin is internally pulled high. When pulled low the PMOS pass transistor turns off and the device enters low-power mode, consuming less than 1A. Bypass capacitor connection -- to improve AC ripple rejection, connect a 1nF capacitor to GND. This will also provide a soft start function. Output pin - should be decoupled with 2.2F or greater output capacitor. See Detailed Description section for further information.
Functional Block Diagram
VIN
Over-Current Protection Over-Temp Protection
OUT
EN BYP VREF
GND
Advanced Analogic Technologies, Inc.
1250 Oakmead Pkwy, Suite 310, Sunnyvale, CA 94086 (408)524-9684 Fax (408)524-9689 1-47
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Detailed Description
TM
AAT3232
300mA CMOS Low Drop Out Linear Regulator
Output Capacitance vs. Load Current Step Size
10 9
The AAT3232 is intended for use in systems where minimal current consumption is desired. During steady state operation, ground current is 30 A typical. All remaining current is available to run the load. This part can also be run with drop out voltages as small as 300 mV allowing very efficient systems to be designed. Several compromises have been made for this device to operate with both low steady state current consumption and very low drop out voltage. The primary compromise is the requirement of larger capacitors over those required by other power hungry high performance LDO's. Since the AAT3232 has considerably faster response than some ultra low current consumption LDOs available, it should not be considered a low performance LDO. The second compromise is the inability to sink current. If current is sourced by the load rather than sunk by the load, the AAT3232 will simply stop supplying current rather than actively reducing the output voltage. As long as the output voltage does not exceed the absolute maximum specification, the AAT3232 will not be damaged. Output Capacitor Output capacitor size is dependent upon the magnitude and the rate of change of the load variation. 10 F tantalum or 5.6 F ceramic is needed only if the load will change by 270 mA (90% of Imax) in less than a couple of microseconds. Smaller capacitors can be used if the output current step size, or rate of change, is less. (See graph titled Output Capacitance vs. Load Current Step Size.) In addition, if adequate bypassing is used at the load, the output capacitor near the LDO can be reduced. The AAT3232 has been optimized for operation with capacitors that are not of the low series resistance type. There are two benefits of using an LDO designed to work with series resistance. First, capacitors sized 10 F or greater with low ESR are generally more expensive than the higher ESR types such as tantalum and electrolytic. Secondly, output capacitors need not be placed next to the regulator. Most applications use a large higher-ESR capacitor placed near the
Capacitance (uF)
8 7
ESR = 1.0 ESR = 0.01
6 5 4 3 2 1 0 0 50 100 150 200 250 300
ESR = 0.5
Step size (mA)
regulator and low ESR decoupling capacitors placed near the load. In cases where very compact design is desirable, a small 1206 case size ceramic capacitor and the load are placed and connected immediately adjacent to the LDO and the trace from the output pin to the output capacitor should have at least 5 milliohms of resistance. For example at least ten squares should be used on a one ounce copper layer. Also see Layout Tips, below. Enable The enable pin is the on/off switch for the LDO. When it is a logic high, the LDO is functioning normally. When it is a logic low, the LDO is in a low power, shut down mode. It has standard CMOS voltage levels set by the AAT3232 input voltage. Voltages at this terminal should be within the absolute maximum rating (-0.5V, to Vin + 0.5V). The enable pin is internally pulled up so that it may be left floating for normal operation. However, since the pull up current is only 500 nA, if open drain logic is used to drive the enable pin, several hundred microseconds may be required for the enable voltage to reach a logic high level. Cnoise The LDO's internal reference can be bypassed by connecting a capacitor from BYP to GND, reducing most of the internally generated noise seen at the output. (See graph titled Output Noise in the previous section.) A large capacitor on Cnoise also improves the PSRR of the AAT3232. (See graph titled Power Supply Rejection Ratio) In addition, a large capacitor
Advanced Analogic Technologies, Inc.
1250 Oakmead Pkwy, Suite 310, Sunnyvale, CA 94086 (408)524-9684 Fax (408)524-9689 1-48
3232.2000.05.0.98
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TM
AAT3232
300mA CMOS Low Drop Out Linear Regulator
to reject signals above one kilohertz, which is where the AAT3232's PSRR rolls off. Layout Since the AAT3232 is designed to operate with series resistance, it is not necessary to have the regulator close to the output capacitor. However, if a ceramic output capacitor is used, a small amount of ESR should be placed between the output capacitor and the regulator; 10 squares of trace on 1 oz. copper (about 5 m ) is enough, but 10 m gives better results. The load should be connected to the output capacitor's side of the resistive trace rather than the regulator's side of the resistive trace. PC board layout guidelines (in order of importance): 1. Cnoise capacitor to BYP and GND: Traces should be kept short. 2. Input capacitor to Vin and GND: Traces should be wide and short. 3. Filter resistor to Input capacitor (for the case of additional PSRR filtering): Connection need not be short but other loads should not be connected to the LDO side of the resistor. 4. Enable is not sensitive to position.
slows down the rate at which the reference turns on. The result is that output voltage climbs slowly when the LDO is turned on either by applying power to the input terminal or by activating Enable. (See graph titled Turn On / Turn Off.) As a result, Cnoise can also be used as a soft start adjustment. Input Capacitor The input capacitor has two purposes: The first is to prevent load current surges from injecting noise onto the line. The second is to prevent line noise from affecting the operation of the regulator. In most circuits, the same value capacitor is used for input and output capacitors. If cost and space are an issue, a ceramic capacitor of a few microfarads works well. Additional PSRR In cases where greater PSRR than normally provided by the AAT3232 is required, additional filtering may be placed on the input line. This allows the filter to drop voltage without affecting the load voltage. For example, if the maximum load required is 100mA, and a drop out voltage of 1.5 volts is available, then a 10 ohm resistor and a 6.8uF capacitor can be used as an input filter. For optimal results, the input filter should be designed
Advanced Analogic Technologies, Inc.
1250 Oakmead Pkwy, Suite 310, Sunnyvale, CA 94086 (408)524-9684 Fax (408)524-9689 1-49
3232.2000.05.0.98
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Ordering Information
TM
AAT3232
300mA CMOS Low Drop Out Linear Regulator
Output Voltage 2.5V 2.7V 2.8V 3.0V 3.3V 3.5V 3.8V
Package SOT-23-5 SOT-23-5 SOT-23-5 SOT-23-5 SOT-23-5 SOT-23-5 SOT-23-5
Marking
Part Number Bulk N/A N/A N/A N/A N/A N/A N/A Tape and Reel AAT3232IGV-2.5-T1 AAT3232IGV-2.7-T1 AAT3232IGV-2.8-T1 AAT3232IGV-3.0-T1 AAT3232IGV-3.3-T1 AAT3232IGV-3.5-T1 AAT3232IGV-3.8-T1
Advanced Analogic Technologies, Inc.
1250 Oakmead Pkwy, Suite 310, Sunnyvale, CA 94086 (408)524-9684 Fax (408)524-9689 1-50
3232.2000.05.0.98
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TM
AAT3232
300mA CMOS Low Drop Out Linear Regulator
Pin Configuration
5-lead SOT-23 (Top View) VIN GND EN 15 2 34 VOUT BYP
Package Information
SOT-23-5
e S1
Dim A A1 A2 b c D E e H L S S1
I
E
H
D
A2 A1
A c L
Millimeters Min Max 1.00 1.30 0.00 0.10 0.70 0.90 0.35 0.50 0.10 0.25 2.70 3.10 1.40 1.80 1.90 2.60 3.00 0.37 0.45 0.55 0.85 1.05 1 9
Inches Min Max 0.039 0.051 0.000 0.004 0.028 0.035 0.014 0.020 0.004 0.010 0.106 0.122 0.055 0.071 0.075 0.102 0.118 0.015 0.018 0.022 0.033 0.041 1 9
S
b
Advanced Analogic Technologies, Inc.
1250 Oakmead Pkwy, Suite 310, Sunnyvale, CA 94086 (408)524-9684 Fax (408)524-9689 1-51
3232.2000.05.0.98
$1$/2*,&
7(&+
TM
AAT3232
300mA CMOS Low Drop Out Linear Regulator
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Advanced Analogic Technologies, Inc.
1250 Oakmead Pkwy, Suite 310, Sunnyvale, CA 94086 (408)524-9684 Fax (408)524-9689 1-52
3232.2000.05.0.98

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