AAT3218 Datasheet, PDF (8/18 Pages) List of Unclassifed Manufacturers – 150mA MicroPower™ High Performance LDO

AAT3218
150mA MicroPower™ High Performance LDO
Functional Block Diagram
IN
OUT
Active
Feedback
Control
Error ⁺
Amplifier
-
Over-Current
Protection
Over-
Temperature
Protection
Fast
EN
Start
Control
Voltage
Reference
BYP
Functional Description
The AAT3218 is intended for LDO regulator applica-
tions where output current load requirements range
from no load to 150mA.
The advanced circuit design of the AAT3218 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 tim-
ing, such as GSM cellular telephone handsets.
The high-speed turn-on capability of the AAT3218 is
enabled through the implementation of a fast start
control circuit, which accelerates the power up behav-
ior of fundamental control and feedback circuits with-
in 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 AAT3218 has very fast transient response char-
acteristics, which is an important feature for applica-
tions where fast line and load transient response is
8
GND
required. This rapid transient response behavior is
accomplished through the implementation of an
active error amplifier feedback control. This propri-
etary circuit design is unique to this MicroPower™
LDO regulator.
The LDO regulator output has been specifically opti-
mized to function with low cost, low ESR ceramic
capacitors. However, the design will allow for opera-
tion 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 C_BYPASS
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 AAT3218 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.
3218.2004.02.1.0