AME
AME5258
n
General Description
The AME5258 is a high efficiency monolithic synchro-
nous buck regulator using a constant frequency, current
mode architecture. The device is available in an adjustable
version and fixed output voltages of 1.2V, 1.8V, 2.5V and
3.3V. Supply current with no load is 300µA and drops to
<1µA in shutdown. The 2.5V to 5.5V input voltage range
makes the AME5258 ideally suited for single Li-Ion bat-
tery-powered applications. 100% duty cycle provides low
dropout operation, extending battery life in portable sys-
tems. PWM pulse skipping mode operation provides very
low output ripple voltage for noise sensitive applications.
At very light load, the AME5258 will automatically skip
pulses in pulse skip mode operation to maintain output
regulation.
The AME5258 is simple to use. As with standard
LDO's,Input and output capacitor are required. The only
other element is a small, low cost, 2.2µH inductor.Low
output voltages are easily supported with the 0.6V feed-
back reference voltage. And 100% duty cycle when Vin
approaches Vout.
1.5MHz, 600mA
Synchronous Buck Converter
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Applications
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Cellular Phones
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Digital Cameras
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Portable Electronics
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USB Devices
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MP3 Players
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LDO Replacement
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Typical Application
Fixed Output Voltage
2.2µH
V
IN
C
IN
4.7µF
CER
IN
SW
V
OUT
AME5258
EN
GND
OUT
C
OUT
10µF
CER
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Features
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High Efficiency:
Up to 96%
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600mA Output Current at V
IN
=3V
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2.5V to 5.5V Input Voltage Range
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1.5MHz Constant Frequency Operation
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No Schottky Diode Required
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Low Dropout Operation: 100% Duty Cycle
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0.6V Reference Allows Low Output
Voltages
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Shutdown Mode Draws<1µA Supply
Current
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Current Mode Operation for Excellent
Line and Load Transient Response
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Overtemperature Protection
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Internal Soft Start
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Space Saving 5-Pin SOT-25 Package
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Meet RoHS Standards
Figure 1: High Efficiency Step-Down Conventer
Adjustable Output Voltage
V
IN
= 2.5V to 5.5V
V
IN
IN
C
IN
4.7µF
CER
2.2µH
SW
22pF
FB
GND
R2
442K
R1
887K
V
OUT
1.8V
600mA
C
OUT
10µF
CER
AME5258
EN
V
OUT
=V
FB
(R1+R2)/R2
Figure 2: 1.8V at 600mA Step-Down Requlator
Rev.A.05
1
AME
AME5258
n
Pin Configuration
SOT-25
Top View
5
4
1.5MHz, 600mA
Synchronous Buck Converter
( Fixed Output )
AME5258-AEVxxx
1. EN
2. GND
SOT-25
Top View
5
4
( Adjustable Output )
AME5258-BEVADJ
1. EN
2. GND
AME5258
3. SW
4. IN
5. OUT
AME5258
3. SW
4. IN
5. FB
1
2
3
1
2
3
* Die Attach:
Conductive Epoxy
* Die Attach:
Conductive Epoxy
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Pin Description
Pin Number
Pin Name
AME5258-AEVxxx
AME5258-BEVADJ
Enable Control Input.
Forcing this pin above 1.5V enables the part. Forcing
this pin below 0.3V shuts down the device. In shutdown,
all functions are disabled drawing <1µA supply current.
Do not leave EN floating.
Ground Pin
Switch Node Connection to Inductor.
This pin connects to the drains of the internal main and
synchronous power MOSFET switches.
Main Supply Pin.
Must be closely decoupled to GND, Pin2, with a 4.7µF
or greater ceramic capactior.
Feedback Pin.
Receives the feedback voltage from an external resistive
divider across the output.
Output Voltage for fixed version
Pin Description
1
1
EN
2
2
GND
3
3
SW
4
4
IN
N/A
5
FB
5
N/A
OUT
Rev.A.05
3
AME
AME5258
n
Available Options
Part Number
AME5258-BEVADJ
AME5258-AEV120
AME5258-AEV180
AME5258-AEV250
AME5258-AEV330
1.5MHz, 600mA
Synchronous Buck Converter
Marking*
BWMMXX
BYRMXX
BYJMXX
BYNMXX
BYFMXX
Output Voltage
ADJ
1.2V
1.8V
2.5V
3.3V
Package
SOT-25
SOT-25
SOT-25
SOT-25
SOT-25
Operating Ambient
Temperature Range
-40
O
C to +85
O
C
-40
O
C to +85
O
C
-40
O
C to +85
O
C
-40
O
C to +85
O
C
-40
O
C to +85
O
C
Note:
1. The first 3 places represent product code. It is assigned by AME such as BWM.
2. A bar on top of first letter represents Green Part such as BWM.
3. The last 3 places MXX represent Marking Code. It contains M as date code in "month", XX as LN code and
that is for AME internal use only. Please refer to date code rule section for detail information.
4. Please consult AME sales office or authorized Rep./Distributor for the availability of output voltage and package
type.
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Absolute Maximum Ratings
Parameter
Input Supply Voltage
EN, FB Voltages
SW Voltage
P-Channel Switch Source Current (DC)
N-Channel Switch Sink Current (DC)
ESD Classification
Symbol
V
IN
V
EN
,V
FB
V
SW
I
SW
I
SW
Maximum
6
V
IN
-0.3 to (V
IN
+0.3)
900
900
C*
Unit
V
V
V
mA
mA
Caution: Stress above the listed in absolute maximum ratings may cause permanent damage to the device.
* HBM C: 4000V ~ 6000V
Rev.A.05
5
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