AME
AME5142/5142A/5142B
n
General Description
The AME5142/5142A/5142B is a Boost DC/DC con-
verter specifically designed to drive white LEDs with a
constant current. The device can drive 1 to 6 LEDs in
series or multiple strings from a Li-lon cell. Series con-
nection of the LEDs provides identical LED currents re-
sulting in uniform brightness and eliminating the need for
ballast resistors. The AME5142/5142A/5142B switches
at 1.2MHz, allowing the use of tiny external components.
The input and output capacitor can be as small as 1µF(or
4.7µF), saving space and cost versus alternative solu-
tions. A low feedback voltage minimizes power loss in
the current setting resistor for better efficiency. The
AME5142/5142A/5142B is available in SOT-26/TSOT-26
& SOT-25/TSOT-25 packages.
The only difference between AME5142, AME5142A and
AME5142B is feedback trip point. The AME5142 is 0.15V
and AME5142A/5142B is 0.104V.
High Efficiency 6 White LED Driver
With Open LED Protection
n
Typical Application
V
IN
2.7V to 5.5V
C
IN
4.7µF
L1
10µH
V
OUT
IN
SW
C
OUT
1µF
AME5142
AME5142A
EN
AME5142B
OVP
GND
FB
R1
7.5Ω
Figure 1: Circuit For Driving 2 White LEDs
L1
10µH
V
OUT
IN
SW
C
OUT
1µF
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Features
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1.2MHz Fixed Switching Frequency
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28V Over Voltage Protection
l
Over Temperature Protection
l
Under Voltage Lockout Protection
l
Internal Soft Start
l
30V Internal Switch
l
Drives Up to 6 LEDs from a 2.7V Supply at
20mA
l
Only small external Capacitors and Inductor
required
l
Cycle-by-Cycle Current Limiting
l
Up to 88% Efficiency
l
Meet RoHS Standards
V
IN
2.7V to 5.5V
C
IN
4.7µF
AME5142
AME5142A
EN
AME5142B
OVP
GND
FB
R1
7.5Ω
Figure 2: Circuit For Driving 4 White LEDs
L1
10µH
V
OUT
IN
SW
C
OUT
1µF
V
IN
2.7V to 5.5V
C
IN
4.7µF
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Applications
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LCD Bias
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Hand-held Computers
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Battery Backup
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Digital Cameras
l
Personal Navigation Device
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Digital Picture Frame
l
Smart Phone
Rev. C.02
AME5142
AME5142A
EN
AME5142B
OVP
GND
FB
R1
7.5Ω
Figure 3: Circuit For Driving 6 White LEDs
1
AME
AME5142/5142A/5142B
Function Block Diagram
EN
OVP
SW
High Efficiency 6 White LED Driver
With Open LED Protection
SHUTDOWN
CIRCUITRY
IN
Vref
1.25V
Vref
UVLO
OTP
R
+
R
RAMP
GENERATOR
-
R
Q
S
0.15V
+
GM
-
*
FB
DRIVER
CURRENT
LIMIT COMP
MS1
MS
Soft
Start
Rc
Oscillator
Cc
*
AME5142
feedback trip point is 0.15V. AME5142A and AME5142B feedback trip point is 0.104V.
Figure 4 : AME5142/5142A/5142B Block Diagram
2
+
-
GND
Rev. C.02
AME
AME5142/5142A/5142B
n
Pin Configuration
SOT-25/TSOT-25
Top View
5
4
High Efficiency 6 White LED Driver
With Open LED Protection
SOT-26/TSOT-26 (Recommend)
Top View
AME5142AEEV
AME5142AAEEV
6
5
4
AME5142AEEY
AME5142AAEEY
AME5142BAEEY
1. SW
2. GND
3. FB
AME5142
AME5142A
1. SW
2. GND
3. FB
AME5142
AME5142A
AME5142B
1
2
3
4. EN
5. IN
1
2
3
4. EN
5. OVP
6. IN
(Recommend)
Die Attach:
Conductive Epoxy
Die Attach:
Conductive Epoxy
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Pin Description
AME5142AEEV/AME5142AAEEV
Pin Number
1
Pin Name
SW
Pin Description
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.
Ground.
Tie directly to ground plane.
Output voltage feedback input.
Connect the ground of the feedback network to an AGND (Analog Ground)
plane which should be tied directly to the GND pin.
Enable control input, active high.
The enable pin is an active high control. Tie this pin above 1.5V to enable
the device. Tie this pin below 0.4V to turn off the device.
Analog and Power input.
Input Supply Pin. Bypass this pin with a capacitor as close to the device
as possible.
2
GND
3
FB
4
EN
5
IN
Rev. C.02
3
AME
AME5142/5142A/5142B
n
Pin Description
AME5142AEEY/AME5142AAEEY/AME5142BAEEY
(Recommend)
High Efficiency 6 White LED Driver
With Open LED Protection
Pin Number
1
Pin Name
SW
Pin Description
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.
Ground.
Tie directly to ground plane.
Output voltage feedback input.
Connect the ground of the feedback network to an AGND(Analog Ground)
plane which should be tied directly to the GND pin.
Enable control input, active high.
The enable pin is an active high control. Tie this pin above 1.5V to enable
the device. Tie this pin below 0.4V to turn off the device.
Over Voltage Protection.
Analog and Power input.
Input Supply Pin. Bypass this pin with a capacitor as close to the device
as possible.
2
GND
3
FB
4
EN
5
OVP
6
IN
4
Rev. C.02
AME
AME5142/5142A/5142B
n
Ordering Information
AME5142 x x x x xxx x
Special Feature
Output Voltage
Number of Pins
Package Type
Operating Ambient Temperature Range
Pin Configuration
High Efficiency 6 White LED Driver
With Open LED Protection
Pin
Configuration
A
(SOT-25)
(TSOT-25)
Operating Ambient
Temperature
Range
E: -40
O
C to +85
O
C
Package
Type
E: SOT-2X
Number
of
Pins
V: 5
Y: 6
Output Voltage
Special Feature
1. SW
2. GND
3. FB
4. EN
5. IN
1. SW
2. GND
3. FB
4. EN
5. OVP
6. IN
ADJ: Adjustable
Y: Lead free & Low
profile
Z: Lead free
A
(SOT-26)
(TSOT-26)
Rev. C.02
5
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