DATA SHEET
AAT2500
1MHz Step-Down Converter/LDO Regulator
General Description Features
The AAT2500 is a member of Skyworks' Total Power V Range: 2.7V to 5.5V
IN
Management IC (TPMIC) product family. It is a low 300mA LDO Current Output
dropout (LDO) linear regulator and a step-down con- 400mV LDO Dropout Voltage at 300mA
verter with an input voltage range of 2.7V to 5.5V, mak- High Output Accuracy: 1.5%
ing it ideal for applications with single lithium-ion/poly- Fast LDO Line / Load Transient Response
mer batteries. 400mA, 96% Efficiency Step-Down Converter
25A No Load Quiescent Current for Step-Down
The LDO has an independent input and is capable of
Converter
delivering up to 300mA. The linear regulator has been
Shutdown Current <1A
designed for high-speed turn-on and turn-off perfor-
Low R 0.4 Integrated Power Switches
DS(ON)
mance, fast transient response, and good power supply
Low Dropout 100% Duty Cycle
rejection ratio (PSRR). Other features include low quies-
1MHz Switching Frequency
cent current and a low dropout voltage.
Internal Soft Start
The 400mA step-down converter is designed to minimize Over-Temperature Protection
external component size and cost while maintaining a Current Limit Protection
low 25A no load quiescent current. Available in TDFN33-12 Package
-40C to +85C Temperature Range
Peak current mode control with internal compensation
provides a stable converter with a low equivalent series
resistance (ESR) ceramic output capacitor for extremely
Applications
low output ripple.
Cellular Phones
For maximum battery life, the step-down converter
Digital Cameras
increases to 100% duty cycle and has a typical 180mV
Handheld Instruments
dropout voltage at 400mA. The output voltage is either
Microprocessor/DSP Core/IO Power
fixed or adjustable with an integrated P- and N-channel
PDAs and Handheld Computers
MOSFET power stage and 1MHz switching frequency.
Portable Media Players
The AAT2500 is available in a 12-pin TDFN33 package,
and is rated over a temperature range of -40C to
+85C.
Typical Application
V = 2.7V to 5.5V
IN
AAT2500 Step-Down Converter Efficiency
C3
10F
3 4
VP VCC
100
5 10
VLDO EN 2.5V
95
2.5V at 400mA
L1
3.3V at 300mA
9 2
ENLDO LX 90
4.7H
6 11
1.8V
85
OUT FB
7 12 80
BYP SGND
C1 75
8 1
GND PGND
C4 4.7F
70
2.2F
C5
U1
65
AAT2500
V = 3.3V
IN
10nF
60
0.1 1 10 100 1000
Load Current (mA)
L1 Sumida CDRH3D16-4R7 C1 Murata GRM219R61A475KE19
C3 Murata GRM21BR60J106KE19
Skyworks Solutions, Inc. Phone [781] 376-3000 Fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com
1
202014A Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice. June 4, 2012
Efficiency (%) DATA SHEET
AAT2500
1MHz Step-Down Converter/LDO Regulator
Pin Descriptions
Pin # Symbol Function
Step-down converter power ground return pin. Connect to the output and input capacitor return. See sec-
1 PGND
tion on PCB layout guidelines and evaluation board layout diagram.
2 LX Power switching node. Output switching node that connects to the output inductor.
3 VP Step-down converter power stage supply voltage. Must be closely decoupled to PGND.
4 VCC Step-down converter bias supply. Connect to VP.
5 VLDO LDO input voltage; should be decoupled with 1F or greater capacitor.
6 OUT 300mA LDO output pin. A 2.2F or greater output low-ESR ceramic capacitor is required for stability.
Bypass capacitor for the LDO. To improve AC ripple rejection, connect a 10nF capacitor to GND. This will
7 BYP
also provide a soft-start function.
8 GND LDO ground connection pin.
9 ENLDO Enable pin for LDO. When connected low, LDO is disabled and consumes less than 1A of current.
10 EN Step-down converter enable. When connected low, LDO is disabled and consumes less than 1A.
Step-down converter feedback input pin. For xed output voltage versions, this pin is connected to the
11 FB converter output, forcing the converter to regulate to the speci c voltage. For adjustable output versions,
an external resistive divider ties to this point and programs the output voltage to the desired value.
Step-down converter signal ground. For external feedback, return the feedback resistive divider to this
12 SGND ground. For internal xed version, tie to the point of load return. See section on PCB layout guidelines
and evaluation board layout diagram.
Exposed paddle (bottom). Use properly sized vias for thermal coupling to the ground plane. See section
EP
on PCB layout guidelines.
Pin Configuration
TDFN33-12
(Top View)
1 12
PGND SGND
2 11
LX FB
3 10
VP EN
4 9
ENLDO
VCC
5 8
VLDO GND
6 7
OUT BYP
Skyworks Solutions, Inc. Phone [781] 376-3000 Fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com
2
202014A Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice. June 4, 2012