AME
AME5144
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General Description
High Efficiency, 37V Step-Up
Converter for 2 to 10 White LEDs
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Features
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Up to 10 LEDs at 25mA
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86% Efficiency
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1.7% Current-Regulation Accuracy
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Output Overvoltage Protection
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Flexible Dimming Control
Analog
Direct-PWM Internal Filter
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1MHz PWM Switching Frequency
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0.1uF Output Capacitor
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Soft-Start Eliminates Inrush Current
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2.6V to 5.5V Input Range
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0.3uA Shutdown current
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DFN 3mm x 3mm x 0.75mm Package with
Exposed Paddle
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All AME’ s Lead Free Products Meet RoHS
Standards
The AME5144 is an efficient driver for up to ten white
LED applications. They are ideal for large LCD backlight
displays in Cell Phone, PDAs, and other handheld devices.
The AME5144 is switch-mode boost converter with con-
stant LED current, rather than output voltage. The series
connection allows the LED currents to be identical for uni-
form brightness and minimizes the number of trace to the
LEDs. The AME5144 drives series-connected LEDs to
controlled-current pin which connected a typically 13Ω
sense resistor, not an expensive fraction-ohm value.
Fast 1MHz current-mode PWM operation allows for small
input and output capacitors and a small inductor while mini-
mizing ripple on the input supply/battery. Soft-start elimi-
nates inrush current during startup. To control LED bright-
ness, the LED current can be pulsed by applying a single
analog/PWM signal with a frequency range from 200Hz to
30KHz for the control pin CTRL.
The AME5144 is available in space saving, 8 pin, 3mm x
3mm x 0.75mm DFN package.
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Applications
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Cell Phones and Smart Phones
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PDAs, Palmtops, and Wireless Handhelds
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e-Books and Subnotebooks
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White LED Display Backlighting
S
-
ie
C
Rev.D.01
1
AME
AME5144
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Typical Application
High Efficiency, 37V Step-Up
Converter for 2 to 10 White LEDs
L=22µH
V
IN
C
IN
2.2µF
Output
Up to 37V
SW
C
OUT
0.1µF
OUT
AME5144
Analog or
PWM Dimming
IN
CTRL
PGND
GND
200Hz to 30KHz
CS
COMP
C
COMP
0.1µF
2 to 10 LEDs
R
SENSE
13Ω
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Function Block Diagram
170mV
8.2ms
CTRL
Bright
Control
CS
SW
Ramp
Generator
PWM
Control
Driver
PGND
OVLO
Gm
OUT
Shutdown
Comp
GND
Current
Limit
Oscillator
UVP
IN
2
Rev. D.01
AME
AME5144
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Pin Configuration
DFN-8C
(3mmx3mmx0.75mm)
Top View
8
7
6
5
High Efficiency, 37V Step-Up
Converter for 2 to 10 White LEDs
AME5144-AVAxxx
1. OUT
2. IN
3. CTRL
4. CS
AME5144
5. COMP
6. GND
7. PGND
* Die Attach:
Conductive Epoxy
1
2
3
4
8. SW
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Pin Description
Pin Number
Pin Name
Pin Description
Overvoltage Sense. When OUT is greater than 38.5V(Typ.), the internal n-
channel MOSFET turns off until OUT drops below 37V(Min), then the IC reenters
soft-start Connect a 0.1uf ceramic capacitor from OUT to ground. In shutdown,
V
OUT
is one diode drop below V
IN
.
C
Input Voltage Supply. The input voltage range is 2.6V to 5.5V. Connect a
2.2uF ceramic capacitor from IN to GND.
Brightness Control pin. Either an Analog or PWM control signal can be used.
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The PWM signal must be between 200Hz and 30KHz. Varying the voltage from
+0.24V to +1.65V adjusts the brightness from dim to 100% brightness,
respectively. Any voltage above +1.65V does not increase brightness. Hold
CTRL below 100mV to shut down the IC after an 8.2ms delay.
Current Sense Feedback input. Connect a resistor from CS to GND to set the
LED bias current. The voltage at CS regulates to V
CRTL
/5 or 0.330V.
Compensation input. Connect a 0.1µF Ceramic Capacitor(Ccomp) from COMP
to GND. C
comp
stabilizes the converter, controls soft-start and lowpass filters
direct PWM dimming at CTRL. Ccomp discharges to 0V through an internal
20KΩ resistor in showdown.
Ground. Connect to PGND and exposed pad directly under the IC.
Power Ground. Connect to PGND and exposed pad directly under the IC.
Inductor Connection. Connect SW to the node between the inductor and
schottky diode. SW is high impedance in shutdown.
3
1
OUT
2
IN
3
CTRL
4
CS
5
COMP
6
7
8
Rev.D.01
GND
PGND
SW
AME
AME5144
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Ordering Information
AME5144 - x x x xxx
High Efficiency, 37V Step-Up
Converter for 2 to 10 White LEDs
Output Voltage
Number of Pins
Package Type
Pin Configuration & Special Feature
Pin Configuration &
Special Feature
A
(DFN-8C)
Package
Type
V: DFN
Number of
Pins
A: 8
Output Voltage
1. OUT
2. IN
3. CTRL
4. CS
5. COMP
6. GND
7. PGND
8. SW
ADJ: Adjustable
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Available Options
Part Number
AME5144-AVAADJ
Marking*
A5144
AMYMXX
Output Voltage
ADJ
Package
DFN-8C
Operating Ambient
Temperature Range
-40
O
C to +85
O
C
Note:
1. The first 2 places represent product code. It is assigned by AME such as AM.
2. Y is year code and is the last number of a year. Such as the year code of 2008 is 8.
3. A bar on top of first letter represents Green Part such as A5144.
4. 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.
5. Please consult AME sales office or authorized Rep./Distributor for the availability of output voltage and package
type.
4
Rev. D.01
AME
AME5144
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Absolute Maximum Ratings
Parameter
V
IN
, to GND
CTRL, CS, COMP, to GND
SW, OUT to GND
PGND to GND
ESD Classification
High Efficiency, 37V Step-Up
Converter for 2 to 10 White LEDs
Maximum
-0.3 to 6.0
-0.3 to (V
IN
+ 0.3)
-0.3 to 40
-0.3 to 0.3
B*
Unit
V
V
V
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
Storage Temperature Range
Ambient Temperature Range
Junction Temperature Range
C
Rating
-65 to +150
-40 to +85
-40 to +125
Unit
o
C
C
C
o
o
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Thermal Information
Parameter
Thermal Resistance*
(Junction to Case)
Thermal Resistance
(Junction to Ambient)
Internal Power Dissipation
Solder Iron (10 Sec)**
DFN-8C
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Package
Die Attach
Symbol
θ
JC
Maximum
17
Unit
o
C/W
Conductive
Epoxy
θ
JA
P
D
125
o
C/W
mW
o
800
350
C
* Measure
θ
JC
on backside center of molding compund if IC has no tab.
** MIL-STD-202G 210F
Rev.D.01
5
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