AME, Inc.
1
AME5138
Micropower Step-Up
DC/DC Converter
The AME5138 is a fixed off-time step-up DC/DC con-
verter in a small 5-lead SOT-25 package.The AME5138
is ideal for LCD panels requiring low current and high effi-
ciency as well as LED applications for cellular phone back-
lighting, PDAs,and other hand-held devices. The low 400ns
off-time allows the use of tiny external components.
AME5138 is designed to drive up to four white LEDs
in series with a constant current from a single Li-lon bat-
tery. To control LED brightness, the LED current can be
adjusted by applying a PWM (pulse width modulated)
signal with a frequency range of 100Hz to 50KHz to the
EN pin.
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General Description
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Features
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Applications
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Typical Application
l
0.7
internal switch
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Uses small surface mount components
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Adjustable output voltage up to 20V
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2V to 5.5V input range
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Input undervoltage lockout
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0.01
µ
A shutdown current
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Small 5-Lead SOT-25 package
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All AME's lead free Product Meet RoHS
Standard
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White LED Back-Lighting
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Hand-held Devices
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Digital Cameras
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Portable Applications
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LCD Bias Power
Figure 1
Four White LEDs Application in Li-lon
Battery
Figure 2
Typical 20V Application
* I
LED
=V
FB
/R2
C
IN
4.7
µ
F
Ceramic
2
5
1
L
15
µ
H
4
V
IN
2.5V-4.2V
3
R2
13K
D
AME5138
SW
V
IN
FB
GND
EN
C
OUT
1
µ
F
Ceramic
R1
200K
20V
10mA
C
IN
4.7
µ
F
Ceramic
AME5138
V
IN
SW
FB
EN
GND
2
5
1
L
10
µ
H
4
0V
>1.1V
V
IN
2.5V-4.2V
3
R2
80
C
OUT
1µ
F
Ceramic
D
Option for
4LEDs
I
LED
AME, Inc.
2
Micropower Step-Up
DC/DC Converter
AME5138
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Function Block Diagram
Figure 3
AME5138 Block Diagram
C
IN
Driver
Enable
Comp
-
SW
V
IN
L
D
EN
GND
FB
R1
R2
V
OUT
V
OUT
V
IN
400ns one
Shot
CL Adjust
+
Logic
control
Current sensing
Vref=1.23
CL
Comp
+
-
C
OUT
Under Voltage
Lockout
AME, Inc.
3
AME5138
Micropower Step-Up
DC/DC Converter
AME5138
1. SW
2. GND
3. FB
4. EN
5. V
IN
* Die Attach:
Conductive Epoxy
SOT-25
Top View
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Pin Configuration
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Pin Description
1
3
2
5
4
AME5138
Pin Number
Pin Name
Pin Description
1
SW
Power Switch input.
This is the drain of the internal NMOS power switch. Minimize the metal
trace area connected to this pin to minimize EMI.
2
GND
Ground.
Tie directly to ground plane.
3
FB
Output voltage feedback input.
Set the output voltage by selecting values for R1 and R2 using:
Connect the ground of the feedback network to an AGND(Analog Ground)
plane which should be tied directly to the GND pin.
4
EN
Shutdown control input, active low.
The shutdown pin is an active low control. Tie this pin above 1V to enable
the device. Tie this pin below 0.4V to turn off the device.
5
V
IN
Analog and Power input.
Input Supply Pin. Bypassed this pin with a capacitor as close to the device
as possible.
-
=
1
23
.
1
2
1
V
V
R
R
out
AME, Inc.
4
Micropower Step-Up
DC/DC Converter
AME5138
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Ordering Information
Note: ww represents the date code and pls refer to Date Code Rule before Package Dimension.
* A line on top of the first letter represents lead free plating such as BDYww.
Please consult AME sales office or authorized Rep./Distributor for the availability of package type.
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Ordering Information
Operating Ambient Temperature Range
Number of Pins
Package Type
Pin Configuration
Special Feature
AME5138 x x x
x
xxx
x
Output Voltage
Part Number
Marking*
Output Voltage Package
Operating Ambient
Temperature Range
AME5138AEEVADJY
BDYww
ADJ
TSOT-25
-40
O
C to +85
O
C
AME5138AEEVADJZ
BDYww
ADJ
SOT-25
-40
O
C to +85
O
C
A
1. SW
E: -40
O
C to +85
O
C
E: SOT-2X
V: 5
ADJ: Adjustable
Y: Lead free
(SOT-25)
2. GND
& Low profile
3. FB
Z: Lead free
4. EN
5. V
IN
Output Voltage
Special Feature
Pin
Configuration
Operating Ambient
Temperature Range
Package Type
Number
of
Pins
AME, Inc.
5
AME5138
Micropower Step-Up
DC/DC Converter
Parameter
Package
Die Attach
Symbol
Maximum
Unit
Thermal Resistance*
(Junction to Case)
J
C
81
Thermal Resistance
(Junction to Ambient)
JA
260
Internal Power Dissipation
P
D
400
mW
150
o
C
350
o
C
o
C / W
Maximum Junction Temperature
Solder Iron (10 Sec)**
SOT-25
Conductive Epoxy
Parameter
Symbol
Rating
Unit
Input Supply Voltage
V
IN
2 to 5.5
V
Ambient Temperature Range
T
A
-40 to +85
Junction Temperature Range
T
J
-40 to +125
o
C
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Absolute Maximum Ratings
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Recommended Operating Conditions
Caution: Stress above the listed absolute maximum rating may cause permanent damage to the device
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Thermal Information
* Measure
JC
on backside center of molding compund if IC has no tab.
** MIL-STD-202G210F
* HBM B:2000V~3999V
Parameter
Symbol
Maximum
Unit
Input Supply Voltage
V
IN
6
V
EN, V
FB
Voltages
V
EN
,V
FB
V
IN
V
SW Voltage
V
SW
V
OUT
+0.3
V
N-Channel Switch Sink Current
I
SW
800
mA
ESD Classification
B*
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