AAT2504
Adjustable 3-Channel Regulator
General Description
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.
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.
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.
The AAT2504 is available in a Pb-free 3x4mm
QFN34-20 package and is rated over the -40°C to
+85°C temperature range.
Features
•
SystemPower
™
•
•
•
•
•
•
800mA Buck Converter
— V
IN
Range: 2.7V to 5.5V
— V
OUT
Range: 0.9V to V
IN
, Adjustable
— High Efficiency: 95%
— 2MHz Switching Frequency
— Synchronizable to External Clock
— Internal Soft Start
Two 300mA Linear Regulators
— V
IN
Range: 1.8V to 5.5V
— Low Dropout Voltage
— High Output Accuracy: ±1.5%
Low Total Quiescent Current I
Q
(80μA)
Independent Enable Pins
Over-Temperature Protection
QFN34-20 Package
-40°C to +85°C Temperature Range
Applications
•
•
•
•
•
Cellular Phones
Digital Cameras
Handheld Instruments
Microprocessor/DSP Core/IO Power
PDAs and Handheld Computers
Typical Application
L
LX
AAT2504
V
IN
VIN
VLDOA
VLDOB
VP
MODE/SYNC
ENA
ENB
EN
V
OUT
(Step-down)
FB
OUTA
100kΩ
POK
FBA
OUTB
OUTB
POK
R
1
R
1A
OUTA
C
OUT
R
1B
FBB
R
2A
2.2μF
2.2μF
R
2
R
2B
PGND
AGND
2504.2007.06.1.0
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
