AAT2504
Adjustable 3-Channel Regulator
™
SystemPower
General Description
Features
The AAT2504 is a three-channel regulator consist-
ing of a step-down converter with an input voltage
range of 2.7V to 5.5V plus two low dropout (LDO)
linear regulators. The two LDOs have an input volt-
age range of 1.8V to 5.5V, making them well-suited
for post regulating from the step-down converter.
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800mA Buck Converter
— VIN Range: 2.7V to 5.5V
— VOUT Range: 0.9V to VIN, Adjustable
— High Efficiency: 95%
— 2MHz Switching Frequency
— Synchronizable to External Clock
— Internal Soft Start
Two 300mA Linear Regulators
— VIN Range: 1.8V to 5.5V
— Low Dropout Voltage
— High Output Accuracy: 1.5%
Low Total Quiescent Current IQ (80μA)
Independent Enable Pins
The step-down converter optimizes power efficiency
throughout the load range. Pulling the MODE/SYNC
pin high enables "PWM Only" operation, maintaining
constant frequency and low output ripple across the
operating range. Alternatively, the converter may be
synchronized to an external clock to the MODE/
SYNC pin. The step-down converter delivers up to
800mA of output current. The switching frequency is
2MHz, minimizing the size of external components.
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Over-Temperature Protection
QFN34-20 Package
-40°C to +85°C Temperature Range
The two LDOs (LDOA/LDOB) have independent
inputs and are capable of delivering up to 300mA
each. A Power-OK (POK) function provides an open
drain output signal when LDOA is within regulation.
Both LDOs feature low quiescent current and a low
dropout voltage. The output voltages for both LDOs
are adjustable to as low as 0.6V. The linear regula-
tors have independent Enable pins. Typical no load
quiescent current is a low 80µA when the step-
down converter and LDOs are enabled.
Applications
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Cellular Phones
Digital Cameras
Handheld Instruments
Microprocessor/DSP Core/IO Power
PDAs and Handheld Computers
The AAT2504 is available in a Pb-free 3x4mm
QFN34-20 package and is rated over the -40°C to
+85°C temperature range.
Typical Application
L
LX
VOUT (Step-down)
AAT2504
FB
VIN
R1
VIN
OUTA
OUTA
R1A
100kΩ
COUT
VLDOA
VLDOB
POK
FBA
POK
OUTB
VP
OUTB
FBB
R1B
R2B
R2A
R2
MODE/SYNC
ENA
2.2μF
2.2μF
PGND
AGND
ENB
EN
2504.2007.06.1.0
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