A8434
6-Channel High Efficiency Charge Pump White LED Driver
Features and Benefits
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Proprietary adaptive control scheme (1×, 1.5×, 2×)
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0.5% typical WLED current matching
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Drives up to 6 white LEDs
▫
Main display backlight (up to 6 WLEDs)
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Main display and sub display backlight
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Main display and low-current flash/torch
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30 mA per WLED
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2× serial dimming interfaces
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320 mA charge pump capability
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Low EMI design and soft start function
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Short circuit, overvoltage, thermal shutdown protection
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0.75 mm nominal height (very thin profile),
3 × 3 mm footprint packages
Description
The A8434 high efficiency charge pump ICs offer a simple,
low-cost WLED (white LED) driver solution for driving up to
six WLEDs in various application configurations, either all six
backlighting a single display, or for multiple displays, such as
four WLEDs as the main display backlight, with the other two
WLEDs used for backlighting a sub display or a low-current
flash/torch. Using a proprietary control scheme (
1×, 1.5×, and
2×
), the A8434 can deliver well-matched WLED current while
maintaining the highest efficiency and low EMI.
The WLED current is regulated over the entire range of Li+
battery voltage to provide uniform intensity. WLED brightness
and on/off can be controlled for the main display and sub
display/torch through 2 single-wire serial interface pins.
The A8434 is available in an QFN/MLP-16 space-conserving
(3 × 3 mm footprint) ES package.
Applications include:
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White LED backlights for cellular phones, PDAs
Digital cameras, camcorders
Portable audio devices and MP3s
Other portable device white LED backlighting
Package: 16 pin QFN/MLP (suffix ES)
Approximate scale 1:1
Typical Applications
VBATT
2.7 to 5.5 V
VIN
CIN
1 µF
C1
1 µF
C1+
C1–
C2
1 µF
VOUT
LED1
LED2
D1
D2
D3
D4
D5
D6
ENS
GND
LED6
VBATT
2.7 to 5.5 V
VIN
CIN
1 µF
C1
1 µF
C1+
C1–
VOUT
LED1
D1
D2
D3
D4
D5
D6
ENS
GND
LED6
COUT
1 µF
RSET
On/Off and
Dimming
Control
CIN
1
μF
COUT
1 µF
VIN
VIN
C1+
C1–
VOUT
LED1
LED2
D1
D2
D3
D4
D5
D6
C2+
A8434
LED3
C2–
LED4
ISET
ENM
LED5
C2+
A8434
LED3
C2–
LED4
ISET
ENM
ENS
GND
LED5
LED6
RSET
On/Off and
Dimming
Control
V
IN
>V
f
(max)+0.2 V, V
f
= LED forward drop
Figure 1.6 × 30 mA WLED display
C2
1 µF
LED2
C2+
A8434
LED3
C2–
LED4
ISET
ENM
LED5
Figure 3. High efficiency current sink
RSET
On/Off and
Dimming
Control
D1-D4 Main Display; D5-D6 Sub Display
Figure 2. 4 × 30 mA main with 2 × 30 mA sub display
8434-DS, Rev. 1
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
