Page 1
SmartSwitch
™
AAT3237
300mA MicroPower™ LDO with PowerOK
3237.2006.01.1.4 1
General Description
The AAT3237 MicroPower low dropout (LDO) linear regulator is ideally suited for portable applications where low noise, extended battery life, and
small size are critical. The AAT3237 has been
specifically designed for low output noise performance, fast transient response, and high power supply rejection ratio (PSRR).
Other features include low quiescent current, typically 70µA, and low dropout voltage, typically less
than 400mV at full output current. The device is
output short-circuit protected and has a thermal
shutdown circuit for additional protection under
extreme conditions.
The AAT3237 also features a low-power shutdown
mode for extended battery life. A Power-OK opendrain output signals when V
OUT
is in regulation.
The AAT3237 is available in a Pb-free, space-saving 6-pin SOT23 or 8-pin SC70JW package in 13
factory-programmed voltages: 1.2V, 1.5V, 1.8V,
2.0V, 2.3V, 2.5V, 2.7V, 2.8V, 2.85V, 2.9V, 3.0V,
3.3V, or 3.5V.
Features
• Low Dropout: 400mV at 300mA
• Guaranteed 300mA Output
• High Accuracy ±1.5%
• 70µA Quiescent Current
• High Power Supply Ripple Rejection
• Power-OK (POK) Output
• Fast Line and Load Transient Response
• Short-Circuit Protection
• Over-Temperature Protection
• Uses Low Equivalent Series Resistance
(ESR) Ceramic Capacitors
• Shutdown Mode for Longer Battery Life
• Low Temperature Coefficient
• 13 Factory-Programmed Output Voltages
• SOT23 6-Pin or SC70JW 8-Pin Package
Applications
• Cellular Phones
• Desktop Computers
• Digital Cameras
• Notebook Computers
• Personal Portable Electronics
• Portable Communication Devices
Typical Application
PowerLinear
™
查询AAT3237IGU-1.2-T1供应商
V
IN
IN
OUT
AAT3237
ON/OFF
1µF
GND GND
EN
POK
GND
2.2µF
V
OUT
POK
Page 2
AAT3237
300mA MicroPower™ LDO with PowerOK
2 3237.2006.01.1.4
Pin Descriptions
Pin Configuration
SOT23-6 SC70JW-8
(Top View) (Top View)
Pin #
Symbol Function
SOT23-6 SC70JW-8
1 5, 6 IN Input voltage pin; should be decoupled with 1µF or greater
capacitor.
2, 5 8 GND Ground connection pin.
3 7 EN 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 1µA.
4 1 POK Power-OK output. This open-drain output is low when OUT is
out of regulation. Connect a pull-up resistor from POK to OUT.
6 2, 3, 4 OUT Output pin; should be decoupled with 2.2µF ceramic capacitor.
IN
GND
EN
1
2
3
6
5
4
OUT
GND
POK
1
POK
2
OUT
3
OUT
45
OUT
8
7
6
GND
EN
IN
IN
Page 3
Absolute Maximum Ratings
1
TA= 25°C, unless otherwise noted.
Thermal Information
2
Recommended Operating Conditions
Symbol Description Rating Units
V
IN
Input Voltage
3
(V
OUT
+ VDO) to 5.5 V
T Ambient Temperature Range -40 to +85 °C
Symbol Description Rating Units
Θ
JA
Maximum Thermal Resistance (SOT23-6, SC70JW-8) 150 °C/W
P
D
Maximum Power Dissipation (SOT23-6, SC70JW-8) 667 mW
Symbol Description Value Units
V
IN,
POK Input Voltage, POK 6 V
V
ENIN(MAX)
Maximum EN to Input Voltage 0.3 V
I
OUT
DC Output Current PD/(VIN- VO)mA
T
J
Operating Junction Temperature Range -40 to 150 °C
T
LEAD
Maximum Soldering Temperature (at leads, 10 sec) 300 °C
AAT3237
300mA MicroPower™ LDO with PowerOK
3237.2006.01.1.4 3
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 a demo board.
3. To calculate minimum input voltage, use the following equation: V
IN(MIN)
= V
OUT(MAX)
+ V
DO(MAX)
as long as VIN≥ 2.5V.
Page 4
Electrical Characteristics
VIN= V
OUT(NOM)
+ 1V for V
OUT
options greater than 1.5V . VIN= 2.5V for V
OUT
≤ 1.5V . I
OUT
= 1mA, C
OUT
= 2.2µF,
CIN= 1µF, TA= -40°C to +85°C, unless otherwise noted. Typical values are TA= 25°C.
Symbol Description Conditions Min T yp Max Units
V
OUT
Output Voltage Tolerance I
OUT
= 1mA to 300mA
T
A
= 25°C -1.5 1.5
%
TA= -40 to 85°C -2.5 2.5
I
OUT
Output Current V
OUT
> 1.2V 300 mA
V
DO
Dropout Voltage
1, 2
I
OUT
= 300mA 400 600 mV
I
SC
Short-Circuit Current V
OUT
< 0.4V 600 mA
I
Q
Ground Current VIN= 5V, No Load, EN = V
IN
70 125 µA
I
SD
Shutdown Current VIN= 5V, EN = 0V 1 µA
∆V
OUT
/
Line Regulation
3
VIN= V
OUT
+ 1 to 5.0V 0.09 %/V
V
OUT
*∆V
IN
∆V
OUT
(line) Dynamic Line Regulation
V
IN
= V
OUT
+ 1V to V
OUT
+ 2V,
5mV
I
OUT
= 300mA, TR/TF= 2µs
∆V
OUT
(load) Dynamic Load Regulation I
OUT
= 1mA to 300mA, TR<5µs 60 mV
V
EN(L)
Enable Threshold Low 0.6 V
V
EN(H)
Enable Threshold High 1.5 V
I
EN
Leakage Current on Enable Pin VEN= 5V 1 µA
V
POK
POK Trip Threshold V
OUT
Rising, TA= 25°C 90 94 98 % of V
OUT
V
POKHYS
POK Hysteresis 1 % of V
OUT
V
POK(OL)
POK Output Voltage Low I
SINK
= 1mA 0.4 V
I
POK
POK Output Leakage Current V
POK
< 5.5V, V
OUT
in Regulation 1 µA
1kHz 65
PSRR Power Supply Rejection Ratio I
OUT
= 10mA 10kHz 45 dB
1MHz 42
T
SD
Over-Temperature Shutdown
145 °C
Threshold
T
HYS
Over-Temperature Shutdown
12 °C
Hysteresis
e
N
Output Noise 250 µVrms
TC
Output Voltage Temperature
22 ppm/°C
Coefficient
AAT3237
300mA MicroPower™ LDO with PowerOK
4 3237.2006.01.1.4
1. VDOis defined as VIN- V
OUT
when V
OUT
is 98% of nominal.
2. For V
OUT
< 2.1V, VDO= 2.5V - V
OUT
.
3. C
IN
= 10µF.
Page 5
AAT3237
300mA MicroPower™ LDO with PowerOK
3237.2006.01.1.4 5
Typical Characteristics
Unless otherwise noted, VIN= 5V, TA= 25°C.
0
Output Voltage (V)
)
Dropout Voltage vs. Temperature
540
480
IL = 300mA
420
360
300
IL = 150mA
240
180
120
Dropout Voltage (mV)
60
0
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
IL = 100mA
IL = 50mA
Temperature (°C
Dropout Voltage vs. Output Current
500
450
400
350
300
250
200
150
100
50
Dropout Voltage (mV)
0
0 50 100 150 200 250 300
85°C
25°C
-40°C
Output Current (mA)
Dropout Characteristics
3.20
3.00
I
= 0mA
OUT
2.80
I
2.60
2.40
Output Voltage (V)
2.20
I
= 10mA
OUT
2.00
2.70 2.80 2.90 3.00 3.10 3.20 3.30
I
OUT
I
OUT
= 50mA
I
= 150mA
OUT
= 100mA
= 300mA
OUT
Input Voltage (V)
Ground Current vs. Input Voltage
90.00
80.00
70.00
60.00
50.00
40.00
30.00
I
= 0mA
OUT
20.00
Ground Current (µA)
10.00
0.00
2 2.5 3 3.5 4.545
I
OUT
= 10mA
I
= 300mA
OUT
I
= 150mA
OUT
I
= 50mA
OUT
Input Voltage (V)
Quiescent Current vs. Temperature
100
90
80
70
60
50
40
30
20
10
Quiescent Current (µA)
0
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
Temperature (°C)
Output Voltage vs. Temperature
1.203
1.202
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 10
Temperature (°C)
Page 6
Typical Characteristics
Unless otherwise noted, VIN= 5V, TA= 25°C.
Load Transient Response
AAT3237
300mA MicroPower™ LDO with PowerOK
6 3237.2006.01.1.4
Turn-On Time and POK Delay
Line Transient Response
6
5
V
IN
4
3
2
1
V
Input Voltage (V)
OUT
0
-1
-2
V
ENABLE
V
OUT
V
POK
Time (10µs/div)
Time (100µs/div)
(2V/div)
(500mV/div)
(500mV/div)
3.25
3.20
Output Voltage (V)
3.15
3.10
3.05
3.00
2.95
2.90
2.85
Turn-Off Time with POK Delay
VEN (2V/div)
V
POK
V
OUT
Time (200µs/div)
POK Output Response
VIN (2V/div)
V
(2V/div)
OUT
V
(1V/div)
POK
Time (200µs/div)
(2V/div)
(2V/div)
2.90
2.85
2.80
2.75
2.70
Output Voltage (V)
2.65
2.60
V
OUT
I
OUT
Time (100µs/div)
500
400
300
200
100
0
-100
Output Current (mA)
Load Transient Response 300mA
3.00
2.90
Output Voltage (V)
2.80
2.70
2.60
2.50
2.40
2.30
2.20
2.10
V
OUT
I
OUT
Time (10µs/div)
800
Output Current (mA)
700
600
500
400
300
200
100
0
-100
Page 7
Typical Characteristics
Unless otherwise noted, VIN= 5V, TA= 25°C.
AAT3237
300mA MicroPower™ LDO with PowerOK
3237.2006.01.1.4 7
Over-Current Protection
1200
1000
800
600
400
200
Output Current (mA)
0
-200
Time (20ms/div)
V
and V
EN(H)
1.250
1.225
1.200
1.175
1.150
(V)
EN
1.125
V
1.100
1.075
1.050
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
EN(H)
VIN (V)
EN(L)
V
EN(L)
vs. V
IN
AAT3237 Self Noise
10
1
0.1
Noise Amplitude (µV/rtHz)
0.01
0.01 0.1 1 10 100 1000
Frequency (kHz)
Page 8
AAT3237
300mA MicroPower™ LDO with PowerOK
8 3237.2006.01.1.4
Functional Description
The AAT3237 is intended for LDO regulator applications where output current load requirements
range from no load to 300mA.
The advanced circuit design of the AAT3237 provides excellent transient response and fast turn-on
ability. 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.
The AAT3237 has an integrated Power-OK comparator which indicates when the output is out of
regulation.
The device enable circuit is provided to shut down
the LDO regulator for power conservation in portable
products. The enable circuit has an additional output capacitor discharge circuit to assure sharp application circuit turn-off upon device shutdown.
This LDO regulator has complete short-circuit and
thermal protection. The integral combination of
these two internal protection circuits gives the
AAT3237 a comprehensive safety system during
extreme adverse operating conditions. Device
power dissipation is limited to the package type
and thermal dissipation properties. Refer to the
Thermal Considerations section of this datasheet
for details on device operation at maximum output
current loads.
Functional Block Diagram
IN
EN
POK
OUT
Over-Current
Protection
Over-Temperature
Protection
Error
Amplifier
Voltage
Reference
94%
GND
Page 9
Applications Information
To assure the maximum possible performance is
obtained from the AAT3237, please refer to the following application recommendations.
Input Capacitor
Typically, a 1µF or larger capacitor is recommended for CINin most applications. A CINcapacitor is
not required for basic LDO regulator operation.
However, if the AAT3237 is physically located more
than three centimeters from an input power source,
a CINcapacitor will be needed for stable operation.
CINshould be located as closely to the device V
IN
pin as practically possible. CINvalues greater than
1µF 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 CINdue 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 V
OUT
and GND. The C
OUT
capacitor connection to
the LDO regulator ground pin should be made as
direct as practically possible for maximum device
performance.
The AAT3237 has been specifically designed to function with very low ESR ceramic capacitors. For best
performance, ceramic capacitors are recommended.
Typical output cap acitor values for maximum output
current conditions range from 1µF to 10µF.
Applications utilizing the exceptionally low output
noise and optimum power supply ripple rejection
characteristics of the AAT3237 should use 2.2µF or
greater for C
OUT
. If desired, C
OUT
may be increased
without limit.
In low output current applications where output
load is less than 10mA, the minimum value for
C
OUT
can be as low as 0.47µF.
Capacitor Characteristics
Ceramic composition capacitors are highly recommended over all other types of capacitors for use
with the AAT3237. 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.
Equivalent Series Resistance: ESR is a very
important characteristic to consider when selecting a
capacitor . ESR is the internal series resistance associated with a capacitor that 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 0.1µF are typically made from NPO
or C0G materials. NPO and C0G materials generally have tight tolerance and are very stable over
temperature. Larger capacitor values are usually
composed of X7R, X5R, Z5U, or Y5V dielectric
materials. 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
2.2µF Y5V capacitor could be reduced to 1µF 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 that 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 datasheets carefully
when selecting capacitors for LDO regulators.
AAT3237
300mA MicroPower™ LDO with PowerOK
3237.2006.01.1.4 9
Page 10
AAT3237
300mA MicroPower™ LDO with PowerOK
10 3237.2006.01.1.4
POK Output
The AAT3237 features an integrated Power-OK
comparator which can be used as an error flag. The
POK open-drain output goes low when OUT is 6%
below its nominal regulation voltage. Connect a
pull-up resistor from POK to OUT.
Enable Function
The AAT3237 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 2.0V. The LDO regulator will
go into the disable shutdown mode when the voltage on the EN pin falls below 0.6V. If the enable
function is not needed in a specific application, it
may be tied to VINto keep the LDO regulator in a
continuously on state.
When the LDO regulator is in shutdown mode, an
internal 1.5kΩ resistor is connected between V
OUT
and GND. This is intended to discharge C
OUT
when
the LDO regulator is disabled. The internal 1.5kΩ
has no adverse effect on device turn-on time.
Short-Circuit Protection
The AAT3237 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 AAT3237 has an internal thermal protection circuit which will turn on when the device die temperature exceeds 145°C. 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 145°C trip point.
The combination and interaction between the shortcircuit and thermal protection systems allows the
LDO regulator to withstand indefinite short-circuit
conditions without sustaining permanent damage.
No-Load Stability
The AAT3237 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 than the output load voltage, maintaining a reverse bias on the internal parasitic
diode. Conditions where V
OUT
might exceed V
IN
should be avoided since this would forward bias
the internal parasitic diode and allow excessive
current flow into the V
OUT
pin, possibly damaging
the LDO regulator.
In applications where there is a possibility of V
OUT
exceeding VINfor brief amounts of time during normal operation, the use of a larger value CINcapacitor is highly recommended. A larger value of C
IN
with respect to C
OUT
will effect a slower CINdecay
rate during shutdown, thus preventing V
OUT
from
exceeding VIN. In applications where there is a
greater danger of V
OUT
exceeding VINfor extended
periods of time, it is recommended to place a
Schottky diode across VINto V
OUT
(connecting the
cathode to VINand anode to V
OUT
). The Schottky
diode forward voltage should be less than 0.45V.
Page 11
AAT3237
300mA MicroPower™ LDO with PowerOK
3237.2006.01.1.4 11
Ordering Information
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.
Output Voltage Package Marking
1
Part Number (Tape and Reel)
2
1.2V SOT23-6 AAT3237IGU-1.2-T1
1.5V SOT23-6 AAT3237IGU-1.5-T1
1.8V SOT23-6 AAT3237IGU-1.8-T1
2.0V SOT23-6 AAT3237IGU-2.0-T1
2.3V SOT23-6 AAT3237IGU-2.3-T1
2.5V SOT23-6 AAT3237IGU-2.5-T1
2.7V SOT23-6 AAT3237IGU-2.7-T1
2.8V SOT23-6 FBXYY AAT3237IGU-2.8-T1
2.85V SOT23-6 GRXYY AAT3237IGU-2.85-T1
2.9V SOT23-6 GSXYY AAT3237IGU-2.9-T1
3.0V SOT23-6 GMXYY AAT3237IGU-3.0-T1
3.3V SOT23-6 HRXYY AAT3237IGU-3.3-T1
3.5V SOT23-6 AAT3237IGU-3.5-T1
1.2V SC70JW-8 AAT3237IJS-1.2-T1
1.5V SC70JW-8 AAT3237IJS-1.5-T1
1.8V SC70JW-8 AAT3237IJS-1.8-T1
2.0V SC70JW-8 AAT3237IJS-2.0-T1
2.3V SC70JW-8 AAT3237IJS-2.3-T1
2.5V SC70JW-8 AAT3237IJS-2.5-T1
2.7V SC70JW-8 AAT3237IJS-2.7-T1
2.8V SC70JW-8 AAT3237IJS-2.8-T1
2.85V SC70JW-8 AAT3237IJS-2.85-T1
2.9V SC70JW-8 AAT3237IJS-2.9-T1
3.0V SC70JW-8 AAT3237IJS-3.0-T1
3.3V SC70JW-8 AAT3237IJS-3.3-T1
3.5V SC70JW-8 AAT3237IJS-3.5-T1
1. XYY = assembly and date code.
2. Sample stock is generally held on all part numbers listed in BOLD.
Page 12
AAT3237
300mA MicroPower™ LDO with PowerOK
12 3237.2006.01.1.4
Package Information
SOT23-6
All dimensions in millimeters.
2.85 ± 0.15
1.90 BSC
0.95 BSC
0.125
±
1.575
0.075 ± 0.075
10° ± 5°
0.40 ± 0.10 × 6
0.20
±
1.10
0.20
±
2.80
0.25
±
1.20
4°
±
4°
0.60 REF
0.15 ± 0.07
0.45 ± 0.15 0.10 BSC
GAUGE PLANE
Page 13
SC70JW-8
All dimensions in millimeters.
0.50 BSC 0.50 BSC 0.50 BSC
AAT3237
300mA MicroPower™ LDO with PowerOK
3237.2006.01.1.4 13
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
© 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.
Customers are advised 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. AnalogicT ech
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.
7° ± 3°
2.00 ± 0.20
0.225 ± 0.075
1.75 ± 0.10
0.85 ± 0.15
2.20 ± 0.20
1.10 MAX
0.100
0.15 ± 0.05
0.048REF
0.45 ± 0.10
2.10 ± 0.30
4° ± 4°
0.05 ± 0.05
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