AME
AME5253A
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General Description
The AME5253A is a high efficiency monolithic syn-
chronous buck regulator using a constant frequency, cur-
rent mode architecture. Capable of delivering 1A output
current over a wide input voltage range from 2.5V to 5.5V.
Supply current with no load is 400µA and drops to<1µA
in shutdown. The 2.5V to 5.5V input Voltage range makes
the AME5253A ideally suited for single Li-Ion battery-
powered applications. 100% duty cycle provides low drop-
out operation, extending battery life in portable systems.
PWM pulse skipping mode operation provides very low
output ripple voltage for noise sensitive applications. At
very light load, the AME5253A will automatically skip
pulses in pulse skip mode operation to maintain output
regulation.
The internal synchronous switch increases efficiency
and eliminates the need for an external Schottky diode.
Low output voltages are easily supported with the 0.6V
feedback reference voltage. The AME5253A is available
in SOT-25 packages.
Other features include soft start, lower internal refer-
ence voltage with 2% accuracy, over temperature protec-
tion, and over current protection.
1A, 1.5MHz Synchronous
Step-Down Converter
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Applications
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Cellular Telephones
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Personal Information Appliances
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Wireless and DSL Modems
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MP3 Players
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Portable Instruments
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Typical Application
V
IN
= 2.5V to 5.5V
V
IN
IN
C
IN
4.7µF
CER
2.2µH
SW
C
FWD
R1
150K
V
OUT
1.8V
1000mA
C
OUT
10µF
CER
AME5253A
EN
FB
GND
R2
75K
V
OUT
=V
FB
(R1+R2)/R2
Figure 1: 1.8V at 1000mA Step-Down Requlator
C
FWD
: 22pF~220pF
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Features
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High Efficiency: Up to 95%
Shutdown Mode Draws < 1µA Supply Current
2.5V to 5.5V Input Range
Adjustable Output From 0.6V to V
IN
1A Output Current
Low Dropout Operation: 100% Duty Cycle
No Schottky Diode Required
1.5MHz Constant Frequency PWM Operation
SOT-25 Packages
All AME’ s Lead Free Product Meet RoHS
Standard
Rev.A.03
1
AME
AME5253A
n
Pin Configuration
SOT-25
Top View
5
4
1A, 1.5MHz Synchronous
Step-Down Converter
AME5253A-AEVADJ
1. EN
2. GND
3. SW
4. IN
5. FB
AME5253A
1
2
3
Die Attach:
Conductive Epoxy
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Pin Description
Pin Number
1
2
3
4
5
Pin Name
EN
GND
SW
IN
FB
Pin Description
No connection. Not internally connected. Can left floating or
connected to GND.
Ground. Tie directly to ground plane.
Switch Node Connection to Inductor.
Input Supply Voltage Pin.
Bypass this pin with a capacitor as close to the device as possible.
Output voltage Feedback input.
Rev.A.03
3
AME
AME5253A
n
Absolute Maximum Ratings
Parameter
Input Supply Voltage
EN, V
OUT
Voltage
SW Voltage
ESD Classification
1A, 1.5MHz Synchronous
Step-Down Converter
Symbol
V
IN
V
EN
, V
OUT
V
SW
Maximum
-0.3 to 6.5
-0.3 to V
IN
-0.3 to V
IN
B*
Unit
V
Caution: Stress above the listed absolute maximum rating may cause permanent damage to the device.
* HBM B: 2000V~3999V
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Recommended Operating Conditions
Parameter
Supply Voltage Voltage
Ambient Temperature Range
Junction Temperature Range
Symbol
V
IN
T
A
T
J
Rating
2.5 to 5.5
-40 to +85
-40 to +125
Unit
V
o
o
C
C
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Thermal Information
Parameter
Thermal Resistance*
(Junction to Case)
Thermal Resistance
(Junction to Ambient)
Internal Power Dissipation
Solder Iron (10Sec)**
SOT-25
Conductive Epoxy
Package
Die Attach
Symbol
θ
J
C
θ
JA
P
D
Maximum
81
Unit
o
C/W
260
400
350
mW
o
C
* Measure
θ
JC
on center of molding compound if IC has no tab.
** MIL-STD-202G 210F
Rev.A.03
5
ST - Low Power RF
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