AAT2503
Adjustable 3-Channel Regulator
™
SystemPower
General Description
Features
The AAT2503 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.
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800mA Step-Down Converter
— VIN Range: 2.7V to 5.5V
— VOUT Range: 0.9V to VIN
— High Efficiency
— 2MHz Switching Frequency
Two 150mA Low Dropout Regulators
— VOUT Range: 0.6V to VIN
— High Output Accuracy: 1.5ꢀ
85µA of Total IQ
Independent Enable Pins
Integrated Power MOSFETs
Over-Temperature and Current Limit
Protection
QFN34-20 Package
-40°C to +85°C Temperature Range
The step-down converter optimizes power efficien-
cy throughout the load range. Pulling the MODE/
SYNC pin high enables "PWM Only" mode, main-
taining constant frequency and low output ripple
across the operating range. Alternatively, the con-
verter may be synchronized to an external clock
input to the MODE/SYNC pin. The step-down con-
verter delivers up to 800mA of output current, while
consuming 30µA of typical no load quiescent cur-
rent. The switching frequency is 2MHz, minimizing
the size of external components.
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The two LDOs (LDOA/LDOB) have independent
inputs and are capable of delivering up to 150mA
each. A Power-OK (POK) function provides an
open drain output signal when LDOA is within reg-
ulation. 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 regulators have independent Enable pins.
Applications
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Cellular Phones
Digital Cameras
Handheld Instruments
Microprocessor/DSP Core/IO Power
PDAs and Handheld Computers
The AAT2503 is available in a Pb-free 3x4mm
QFN34-20 package and is rated over the -40°C to
+85°C temperature range.
Typical Application
L1
LX
VOUT (Buck)
AAT2503
FB
V
R1
VIN
IN
OUTA
R3
100kΩ
OUTA
R4
C2
10μF
VLDOA
VLDOB
POK
FBA
POK
OUTB
C6
VP
OUTB
FBB
R5
R8
C5
2.2μF
R7
R2
MODE/SYNC
ENA
2.2μF
PGND
AGND
ENB
EN
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