AL3157

AL3157
HIGH EFFICIENCY 1x/2x CHARGE PUMP LED DRIVER
FOR SMALL SCREEN BACKLIGHTING AND FLASHLIGHT
NEW PRODUCT
Description
Pin Assignments
The AL3157 is a low noise, constant frequency charge
pump DC/DC converter that uses a Dual mode load switch
(1x), and doubling (2x) conversion for driving white LEDs.
Low external part count (one 1µF flying capacitor and two
2.2µF capacitors at VIN and VOUT) make this part ideally
suited for small, battery-powered applications
The AL3157 drives 3 channels at up to 30mA for small
screen backlighting and an additional channel up to 210mA
for LED Flash or LED Flashlight – All from a 2.7V to 5.5V
input.
The AL3157 uses two control inputs (EN1/2) to
enable/disable it and PWM dim the LED current. EN2
controls/PWM dims the backlight LEDs at 30mA per
channel and EN1 controls/PWM dims the Flash/Flashlight
LEDs at 210mA.
Each output is equipped with built-in protection for VOUT
short circuit and auto-disable for LED failure conditions.
Built-in soft-start circuitry prevents excessive in-rush
current during start-up and mode switching. A low-current
shutdown feature disconnects the load from VIN to reduce
quiescent current less than 1µA.
The AL3157 is available in a lead-free, space-saving
thermally enhanced 12-pin 3x3mm DFN package.
( Top View )
EN2
•
•
•
•
•
•
•
•
Notes:
12
D1
PGND
2
11
EN1
CN
3
10
D2
4
9
GND
CP
5
8
D3
VOUT
6
7
D4
VIN
Exposed Pad
U-DFN3030-12
Features
•
•
1
Applications
•
•
•
Dual-Mode 1x and 2x Charge Pump
Up to 300mA drive capability
o 3-channel for backlight – 30mA/ch
o 1-channel for Flight/light – 210mA
VIN Range: 2.7V to 5.5V
Two simple PWM dimming control inputs up to
50kHz
1.2 MHz Constant Switching Frequency
Built-In Thermal, Open-Circuit and VOUT short circuit
Protection
Soft Start for reducing in-rush current
IQ <1µA in Shutdown
Thermally-Enhanced DFN3030-12 Package:
Available in “Green” Molding Compound (No Br, Sb)
Lead Free Finish/ RoHS Compliant (Note 1)
Smart Touch Phone LED Backlighting
PDA White LED backlighting
Backlighting + Torch light
1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
http://www.diodes.com/products/lead_free.html
Typical Application Circuit
VIN
4
Flash/
Light
(EN1)
VIN
2.2µF
CIN
5
1µF
C1
3
EN1
EN2
11
1
VOUT
CN
D1
EN2
2
Document number: DS35116 Rev. 1 - 2
2.2µF
COUT
12
10
D2
8
D3
7
D4
EN1
PGND
AL3157
6
CP
AL3157
Backlight
(EN2)
GND
9
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March 2011
© Diodes Incorporated
AL3157
HIGH EFFICIENCY 1x/2x CHARGE PUMP LED DRIVER
FOR SMALL SCREEN BACKLIGHTING AND FLASHLIGHT
NEW PRODUCT
Pin Descriptions
Pin Name
Pin Number
EN2
1
Enable Pin 2: Controls outputs D2, D3 and D4
Description
PGND
2
Charge Pump Switch Ground: Connect to GND
CN
3
Negative Terminal of Flying Capacitor
VIN
4
Input Power Supply. Decouple with a 2.2µF capacitor between this pin and ground.
CP
5
Positive Terminal of Flying Capacitor
VOUT
6
Charge pump output to drive D1~D4 load circuit. Decouple with a 2.2µF capacitor between
this pin and ground.
D4
7
Current sink input #4. Drive up to 30mA LED current. Connect to VOUT when un-used.
D3
8
Current sink input #3. Drive up to 30mA LED current. Connect to VOUT when un-used.
GND
9
Ground
D2
10
Current sink input #2. Drive up to 30mA LED current. Connect to VOUT when un-used.
EN1
11
Enable Pin 1: Controls output D1
D1
12
Current sink input #1. Drive up to 210mA LED current. Connect to VOUT when un-used.
EP
EP PAD
Exposed Pad (bottom). Connect to GND directly underneath the package.
Functional Block Diagram
CN
CP
VOUT
VIN
SHORT
CIRCUIT
PROTECTION
CHARGE PUMP
SWITCHES
OVER
VOLTAGE
PROTECTION
EN1
DIGITAL CONTROL BLOCK
EN2
D1
BANDGAP
D2
OSCILLATOR
D3
OVER
TEMPERATURE
PROTECTION
CURRENT
CONTROL
D4
UNDER
VOLTAGE
LOCKOUT
GND
AL3157
Document number: DS35116 Rev. 1 - 2
2 of 9
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© Diodes Incorporated
AL3157
HIGH EFFICIENCY 1x/2x CHARGE PUMP LED DRIVER
FOR SMALL SCREEN BACKLIGHTING AND FLASHLIGHT
NEW PRODUCT
Absolute Maximum Ratings (Note 2)
Symbol
ESD HBM
ESD MM
VIN
VEN1,2,3
IOUT
TJ
TLEAD
Notes:
Description
Human Body Model ESD Protection
Machine Model ESD Protection
Input Voltage
EN1, EN2, EN3 to GND Voltage
Maximum DC Output Current
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Rating
2
200
-0.3 to 6
-0.3 to VIN +0.3
300
125
300
Unit
kV
V
V
V
mA
°C
°C
2. Exceeding Absolute Maximum Ratings will cause permanent damage to the device.
Recommended Operating Conditions
Symbol
VIN
VENL(1, 2)
VENH(1,2)
TA
Parameter
Input Voltage
EN1,2 Threshold Low
EN1,2, Threshold High
Operating Ambient Temperature
Min
2.7
0
1.4
-40
Max
5.5
0.4
VIN
85
Unit
V
V
V
°C
Electrical Characteristics
VIN = 4V, CIN = COUT = 2.2µF, C1 = 1µF; TA = 25°C unless otherwise noted.
Symbol
Parameter
Test Conditions
1x Mode, 3.0≤VIN≤5.5, Active,
No Load Current
IQ
Quiescent Current
2x Mode, 3.0≤VIN≤5.5, Active,
No Load Current
ISHDN Shutdown Current
EN1, EN2 = 0
Backlight LED Drive Sink Current
ID2~4
IDX = 30mA
Accuracy (Note 3)
Flash/light LED Drive Sink Current
ID1
ID1 = 210mA
Accuracy (Note 3)
Current Matching Between Any
ID-Match Two Backlight LED Drive Current VF: D2:D4 = 4V
Sink Outputs (Note 4)
Rout
VTH-Dx
VTH-D1
VHS
tSS
fSW
tEN1,2
UVLO
IEN1,2
TSHDN
THYS
θJA
Notes:
Charge Pump VOUT Open Loop
Resistance
5.
Typ.
Max
0.3
0.6
2
5
Unit
mA
1
µA
28.5
30
31.5
mA
199.5
210
220.5
mA
1
2
%
1x mode
0.5
2x mode
4.5
1x to 2x Transition Threshold at
ID = 30mA
D2, D3 and D4 Pins
1x to 2x Transition Threshold at D1
ID1 = 210mA
Pin
Mode Transition Threshold
Soft-Start Time
Switching Frequency
EN1,2 Off Timeout
VIN Under-Voltage Lockout
EN1, 2 Input Leakage
Thermal Shutdown Protection
Thermal Shutdown Hysteresis
Thermal Resistance
U-DFN3030-12 (Note 5)
Junction-to-Ambient
3.
4.
Min
Ω
150
mV
150
mV
500
100
1.2
1.8
-1
2
160
10
55.29
20
2.2
1
mV
µs
MHz
ms
V
µA
o
C
o
C
o
C/W
Determined by the mean of channels 2,3 and 4 currents, EG (ID2 + ID3 + ID4)/3
Determined by the maximum sink current (MAX), the minimum sink current (MIN), and the average sink current (AVG). Two matching
numbers are calculated as (MAX-AVG)/AVG and (AVG-MIN)/AVG. The largest number of the two (worst case) is as the matching data.
Device mounted on FR-4 substrate, 2"*2", 2oz, copper, double-sided PC board.
AL3157
Document number: DS35116 Rev. 1 - 2
3 of 9
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March 2011
© Diodes Incorporated
AL3157
HIGH EFFICIENCY 1x/2x CHARGE PUMP LED DRIVER
FOR SMALL SCREEN BACKLIGHTING AND FLASHLIGHT
Typical Performance Characteristics
Turn-On in 1x Mode
Turn-On in 2x Mode
EN1,2
2V/div
NEW PRODUCT
EN1,2
2V/div
Vout
2V/div
Vout
2V/div
Iin
300mA/div
Iin
300mA/div
VIN=4.2V
TA=25°C
VIN=3.0V
TA=25°C
100us/div
100us/div
Turn-Off in 1x Mode
Turn-Off in 2x Mode
VIN=4.2V
TA=25°C
VIN=3.0V
TA=25°C
EN1,2
2V/div
Vout
2V/div
EN1,2
2V/div
Vout
2V/div
Iin
300mA/div
Iin
300mA/div
200ms/div
200ms/div
Load Characteristics in 2x Mode
PWM Dimming Control (Duty Cycle=50%)
Vin
100mVAC/div
Vout
100mVAC/div
VIN=3.0V
TA=25°C
EN
2V/div
VIN=4V
Freq=20kHz
Duty Cycle=50%
Document number: DS35116 Rev. 1 - 2
TA=25°C
Iin
300mA/div
Iin
100mAAC/div
500ns/div
AL3157
Id1
200mA/div
10us/div
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© Diodes Incorporated
AL3157
HIGH EFFICIENCY 1x/2x CHARGE PUMP LED DRIVER
FOR SMALL SCREEN BACKLIGHTING AND FLASHLIGHT
Typical Performance Characteristics (Continued)
VIN=4V
VF=3.27V
TA=25°C
NEW PRODUCT
Channels 2 to 4
TA=25°C
VIN=4V
Channels 2 to 4
VEN(H)
VIN=2.7V
VIN=4.0V
AL3157
Document number: DS35116 Rev. 1 - 2
5 of 9
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VEN(L)
March 2011
© Diodes Incorporated
AL3157
HIGH EFFICIENCY 1x/2x CHARGE PUMP LED DRIVER
FOR SMALL SCREEN BACKLIGHTING AND FLASHLIGHT
Functional Description
The AL3157 is a dual-mode high efficiency charge pump (1x and 2x) device, driving 3-channel standard backlight LEDs
and one high-current Flash/Torch LED, intended for white LED backlight applications. An internal comparator circuit
compares the voltage at each constant current sink input against a reference voltage. To ensure maximum power
efficiency, the most appropriate switching mode (1x and 2x) is automatically selected.
NEW PRODUCT
The APL3157 requires only three external components: one 1µF ceramic flying capacitor (C1) for the charge pump, one
2.2µF ceramic input capacitor (CIN), and one 2.2µF ceramic charge pump output capacitor (COUT).
The each output channel of the AL3157 can drive three individual LEDs with a maximum current of 30mA per channel and
a Flash/Torch LED with a maximum current of 210mA. These can be paralleled to give a total output current of 300mA.
LED Control Table
EN1
0
0
1
1
EN2
0
1
0
1
D1
OFF
OFF
ON
ON
D2, D3, D4
OFF
ON
OFF
ON
Disabled Current Sinks
Unused current channels must be disabled by connecting the sinks to VOUT with only a small sense current flowing
through the disabled channel.
Soft-Start
Soft-start is incorporated to prevent excessive in-rush current during power-up, mode switching, and transitioning out of
stand-by mode.
Short-Circuit Protection
Short-circuit protection function is incorporated to prevent excessive load current when either flying cap terminals or output
pin electrically tied to a very lower voltage or ground.
Over-Voltage Protection
Over-Voltage Protection function is incorporated to limit the output voltage under a safe value to avoid on-chip device
breakdown.
Under-Voltage Lockout
Under-Voltage lockout feature disables the device when the input voltage drops below UVLO threshold.
Thermal Auto Shutdown
When the die temperature exceeds the thermal limit, the device will be disabled and enter stand-by mode. The operation
resumes whenever the die cools off sufficiently.
PWM Dimming Control
The AL3157 provides simple PWM dimming control through ENx pins, and the current is adjusted by the duty cycle of the
signal applied on ENx pin. The recommended PWM frequency is from 200Hz to 50kHz depending on applications.
.
AL3157
Document number: DS35116 Rev. 1 - 2
6 of 9
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March 2011
© Diodes Incorporated
AL3157
HIGH EFFICIENCY 1x/2x CHARGE PUMP LED DRIVER
FOR SMALL SCREEN BACKLIGHTING AND FLASHLIGHT
Ordering Information
Device
AL3157F-7
Notes:
7.
Package
Packing
F : U-DFN3030-12
7 : 7” Tape & Reel
Package
Code
F
7” Tape and Reel
Quantity
Part Number Suffix
3000/Tape & Reel
-7
Packaging
(Note 7)
U-DFN3030-12
Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at
http://www.diodes.com/datasheets/ap02001.pdf
Marking Information
(1) U-DFN3030-12
( Top View )
XX
Y WX
XX : B7 : AL3157
Y : Year : 0~9
W : Week : A~Z : 1~26 week;
a~z : 27~52 week;
z : represents 52 and 53
X : A~Z : Green
Part Number
Package
Identification Code
AL3157F
U-DFN3030-12
B7
Package Information
0.57/0.63
(1) Package type: U-DFN3030-12
0.15max.
0.10 C
0.25 A
2.9 / 3.1
2.3 / 2.5
2x
0/0.05
0.08 C
B
2x-
0.25 B
Seating plane
C
A
3
0.45typ
0.25/0.55
1.5 / 1.7
R0.
2.9 / 3.1
NEW PRODUCT
AL3157 X - 7
0.18/0.28
0.10 M C A B
Bottom View
AL3157
Document number: DS35116 Rev. 1 - 2
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March 2011
© Diodes Incorporated
AL3157
HIGH EFFICIENCY 1x/2x CHARGE PUMP LED DRIVER
FOR SMALL SCREEN BACKLIGHTING AND FLASHLIGHT
NEW PRODUCT
Tape Orientation (Note 8)
Notes:
8. The taping orientation of the other package type can be found on our website at http://www.diodes.com/datasheets/ap02007.pdf
AL3157
Document number: DS35116 Rev. 1 - 2
8 of 9
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© Diodes Incorporated
AL3157
HIGH EFFICIENCY 1x/2x CHARGE PUMP LED DRIVER
FOR SMALL SCREEN BACKLIGHTING AND FLASHLIGHT
IMPORTANT NOTICE
NEW PRODUCT
DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS
DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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without the express written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:
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B.
A critical component is any component in a life support device or system whose failure to perform can be reasonably expected
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Copyright © 2011, Diodes Incorporated
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AL3157
Document number: DS35116 Rev. 1 - 2
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© Diodes Incorporated
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