PRODUCT DATASHEET
AAT2503178
SystemPower
TM
General Description
The AAT2503 is a three-channel regulator consisting of a
step-down converter with an input voltage range of 2.7V
to 5.5V plus two low dropout (LDO) linear regulators.
The step-down converter optimizes power efficiency
throughout the load range. Pulling the MODE/SYNC pin
high enables “PWM Only” mode, maintaining constant
frequency and low output ripple across the operating
range. Alternatively, the converter may be synchronized
to an external clock input to the MODE/SYNC pin. The
step-down converter delivers up to 800mA of output cur-
rent, while consuming 30μA of typical no load quiescent
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 150mA each. Ultra
low input voltage on the VLDOA and VLDOB pins (down
to 1.62V) allows for efficient post-buck regulation. A
Power-OK (POK) function provides an open drain output
signal when LDOA is within regulation. Both LDOs fea-
ture 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.
The AAT2503 is available in a Pb-free 3x4mm QFN34-20
package and is rated over the -40°C to +85°C tempera-
ture range.
Adjustable 3-Channel Regulator
Features
• 800mA Step-Down Converter
▪
V
IN
Range: 2.7V to 5.5V
▪
V
OUT
Range: 0.9V to V
IN
▪
High Efficiency
▪
2MHz Switching Frequency
• Two 150mA Low Dropout Regulators
▪
LDO Input Voltage Range: 1.62V to 5.5V
▪
V
OUT
Range: 0.6V to V
IN
▪
High Output Accuracy: ±1.5%
• 85μA of Total I
Q
• Independent Enable Pins
• Integrated Power MOSFETs
• 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
L1
LX
AAT2503
V
IN
VIN
VLDOA
VLDOB
VP
MODE/SYNC
ENA
ENB
EN
V
OUT
(Buck)
FB
OUTA
R
3
100kΩ
POK
FBA
OUTB
OUTB
POK
R
1
R
4
OUTA
C2
10μF
R
5
FBB
R
8
PGND
AGND
C6
2.2μF
R
7
C5
2.2μF
R
2
2503.2008.02.1.4
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