AAT3221/2
150mA NanoPower™ LDO Linear Regulator
Functional Block Diagram
IN
Over-Current
Protection
Over-Temperature
Protection
OUT
EN
V
REF
GND
Functional Description
The AAT3221 and AAT3222 are intended for LDO
regulator applications where output current load
requirements range from no load to 150mA. The
advanced circuit design of the AAT3221/2 has been
optimized for very low quiescent or ground current
consumption, making it ideal for use in power man-
agement systems for small battery-operated
devices. The typical quiescent current level is just
1.1µA. AAT3221/2 devices also contain an enable
circuit which has been provided to shut down the
LDO regulator for additional power conservation in
portable products. In the shutdown state, the LDO
draws less than 1µA from input supply.
The LDO also demonstrates excellent power sup-
ply ripple rejection (PSRR) and load and line tran-
sient response characteristics. The AAT3221/2
high performance LDO regulator is especially well
suited for circuit applications that are sensitive to
load circuit power consumption and extended bat-
tery life.
The LDO regulator output has been specifically
optimized to function with low-cost, low-ESR
ceramic capacitors. However, the design will allow
for operation with a wide range of capacitor types.
The AAT3221/2 has complete short-circuit and
thermal protection. The integral combination of
these two internal protection circuits gives the
AAT3221/2 a comprehensive safety system to
guard against extreme adverse operating condi-
tions. Device power dissipation is limited to the
package type and thermal dissipation properties.
Refer to the Thermal Considerations section of this
document for details on device operation at maxi-
mum output load levels.
3221.2005.12.1.11
9
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
