Dual Channel, Step-Down
Converter/Linear Regulator
General Description
The AAT2505 is a member of AnalogicTech's Total
Power Management IC™ (TPMIC™) product fam-
ily. It is a low dropout (LDO) linear regulator and a
step-down converter with an input voltage range of
2.7V to 5.5V, making it ideal for applications with
single cell lithium-ion / polymer batteries.
The LDO has an independent input pin and is capa-
ble of delivering up to 300mA of current. The linear
regulator has been designed for high-speed turn-on
and turn-off performance, fast transient response,
and good power supply rejection ratio (PSRR).
Other features include low quiescent current, low
dropout voltage, and a Power-OK (POK) open drain
output signaling when V
OUT
is in regulation.
The 600mA step-down converter is designed to
operate with 1.4MHz of switching frequency, mini-
mizing external component size and cost while
maintaining a low 27µA no load quiescent current.
Peak current mode control with internal compen-
sation provides a stable converter with a low equiv-
alent series resistance (ESR) ceramic output
capacitor for extremely low output ripple.
For maximum battery life with high voltage outputs,
the step-down converter duty cycle increases to
100%. The output voltage is either fixed or adjustable
with an integrated P- and N-channel MOSFET power
stage and 1.4MHz switching frequency.
The AAT2505 is available in a Pb-free, 12-pin
TDFN33 package and is rated over a temperature
range of -40°C to +85°C.
AAT2505
Features
•
•
SystemPower
™
•
•
•
•
V
IN
Range: 2.7V to 5.5V
300mA LDO
— 400mV Dropout Voltage at 300mA
— High Accuracy: ±1.5%
— Fast Line / Load Transient Response
— Power OK Output
600mA Step-Down Converter
— Up To 98% Efficiency
— 27µA No Load Quiescent Current
— Shutdown Current <1µA
— Low R
DS(ON)
Integrated Power Switches
— Fast Turn-On Time (150µs Typical)
— Low Dropout 100% Duty Cycle
— 1.4MHz Switching Frequency
— Internal Soft Start
Over-Temperature and Current Limit
Protection
TDFN33-12 Package
-40°C to +85°C Temperature Range
Applications
•
•
•
•
•
•
Cellular Phones
Digital Cameras
Handheld Instruments
Microprocessor/DSP Core/IO Power
PDAs and Handheld Computers
Portable Media Players
Typical Application
V
IN
= 2.7V to 5.5V
Efficiency
(V
OUT
= 2.5V; L = 6.8µH)
VP
VLDO
ENLDO
OUT
POK
GND
VCC
EN
LX
FB
SGND
PGND
4
10
C3
10µF
3
5
100
2.5V at 600mA
3.3V at 300mA
9
6
2
11
12
1
6.8µH
Efficiency (%)
L1
90
V
IN
= 3.3V
80
R3 100kΩ
7
8
C4
2.2µF
C1
4.7µF
70
U1
AAT2505
60
0.1
L1 Sumida CDRH3D16-4R7 C1 Murata GRM219R61A475KE19
C3 Murata GRM21BR60J106KE19
1
10
100
1000
Output Current (mA)
2505.2006.06.1.1
1
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