1MHz Step-Down Converter/LDO Regulator
General Description
The AAT2500 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 lithium-ion/polymer batteries.
The LDO has an independent input and is capable
of delivering up to 300mA. 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 fea-
tures include low quiescent current and a low
dropout voltage.
The 400mA step-down converter is designed to
minimize external component size and cost while
maintaining a low 25µA 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, the step-down converter
increases to 100% duty cycle and has a typical
180mV dropout voltage at 400mA. The output volt-
age is either fixed or adjustable with an integrated
P- and N-channel MOSFET power stage and
1MHz switching frequency.
The AAT2500 is available in a 12-pin TDFN33 or
STDFN33 package, and is rated over a tempera-
ture range of -40°C to +85°C.
AAT2500
Features
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SystemPower
™
V
IN
Range: 2.7V to 5.5V
300mA LDO Current Output
400mV LDO Dropout Voltage at 300mA
High Output Accuracy: ±1.5%
Fast LDO Line / Load Transient Response
400mA, 96% Efficiency Step-Down Converter
25µA No Load Quiescent Current for Step-
Down Converter
Shutdown Current <1µA
Low R
DS(ON)
0.4Ω Integrated Power Switches
Low Dropout 100% Duty Cycle
1MHz Switching Frequency
Internal Soft Start
Over-Temperature Protection
Current Limit Protection
Available in TDFN33-12 or STDFN33-12
Package
-40°C to +85°C Temperature Range
Applications
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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
AAT2500 Step-Down Converter Efficiency
VP
VLDO
ENLDO
OUT
BYP
GND
VCC
EN
LX
FB
SGND
PGND
4
10
C3
10μF
3
5
100
2.5V at 400mA
95
2.5V
1.8V
9
6
7
8
2
11
12
1
4.7μH
Efficiency (%)
3.3V at 300mA
L1
90
85
80
75
70
65
60
0.1
1
10
100
C4
2.2μF
C1
4.7μF
C5
10nF
U1
AAT2500
V
IN
= 3.3V
1000
L1 Sumida CDRH3D16-4R7 C1 Murata GRM219R61A475KE19
C3 Murata GRM21BR60J106KE19
Load Current (mA)
2500.2006.05.1.16
1
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