AAT3223
250mA NanoPower™ LDO
Linear Regulator with Power-OK
Functional Block Diagram
IN
OUT
POK
Over-Current
Protection
Over-Temperature
Protection
+
Error
-
Amplifier
1ms
Delay
-
+
EN
91%
VREF
Voltage
Reference
GND
The LDO also demonstrates excellent power supply
ripple rejection, and load and line transient response
characteristics. The AAT3223 is a high performance
LDO regulator that is especially well suited for circuit
applications that are sensitive to load circuit power
consumption and extended battery life.
Functional Description
The AAT3223 is intended for LDO regulator applica-
tions where output current load requirements range
from no load to 250mA. The advanced circuit design
of the AAT3223 has been optimized for very low qui-
escent or ground current consumption, making it
ideal for use in power management systems in small
battery-operated devices. The typical quiescent cur-
rent level is just 1.1µA. The AAT3223 also contains
an enable circuit, which has been provided to shut
down the LDO regulator for additional power conser-
vation in portable products. In the shutdown state,
the LDO draws less than 1µA from the input supply.
The LDO regulator output has been specifically
optimized to function with low-cost, low equivalent
series resistance (ESR) ceramic capacitors; how-
ever, the design will allow for operation over a wide
range of capacitor types.
The AAT3223 has complete short-circuit and ther-
mal protection. The integral combination of these
two internal protection circuits gives the AAT3223 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 section of this datasheet
for details on device operation at maximum output
current loads.
The Power-OK function has been incorporated to
allow notification to application circuits when the
output voltage falls out of regulation. If the output
voltage falls below the regulation threshold limit,
which is compared to a level set by the internal
voltage reference, the POK pin is pulled to ground
through an N-channel MOSFET.
3223.2006.03.1.5
9
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
