A8434 Datasheet, PDF (1/11 Pages) Allegro MicroSystems – 6-Channel High Efficiency Charge Pump White LED Driver

A8434
6-Channel High Efficiency Charge Pump White LED Driver
Features and Benefits
▪ Proprietary adaptive control scheme (1×, 1.5×, 2×)
▪ 0.5% typical WLED current matching
▪ Drives up to 6 white LEDs
▫ Main display backlight (up to 6 WLEDs)
▫ Main display and sub display backlight
▫ Main display and low-current flash/torch
▪ 30 mA per WLED
▪ 2× serial dimming interfaces
▪ 320 mA charge pump capability
▪ Low EMI design and soft start function
▪ Short circuit, overvoltage, thermal shutdown protection
▪ 0.75 mm nominal height (very thin profile),
3 × 3 mm footprint packages
Package: 16 pin QFN/MLP (suffix ES)
Approximate scale 1:1
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:
▪ White LED backlights for cellular phones, PDAs
▪ Digital cameras, camcorders
▪ Portable audio devices and MP3s
▪ Other portable device white LED backlighting
VBATT
2.7 to 5.5 V
VIN
CIN
1 µF
C1
1 µF _C1+
VOUT
D1
LED1
C2
1 µF
C1–
LED2
C2+ ^A8434
D2
D3
LED3
C2–
D4
RSET
ISET
LED4
D5
ENM
LED5
D6
On/Off and
Dimming
ENS _GND LED6
Control
Figure 1.6 × 30 mA WLED display
8434-DS, Rev. 1
Typical Applications
COUT
1 µF
VBATT
2.7 to 5.5 V
CIN
1 µF
C1
1 µF
C2
1 µF
RSET
On/Off and
Dimming
Control
VIN
VOUT
C1+
LED1
C1–
LED2
C2+ A8434
LED3
C2–
ISET
LED4
ENM
LED5
ENS _GND LED6
COUT
1 µF
D1
D2
D3
D4
D5
D6
D1-D4 Main Display; D5-D6 Sub Display
Figure 2. 4 × 30 mA main with 2 × 30 mA sub display
VIN
CIN
1 μF
RSET
On/Off and
Dimming
Control
VIN
VOUT
C1+
D1
LED1
C1–
D2
LED2
C2+ A8434
D3
LED3
C2–
D4
LED4
ISET
D5
ENM
LED5
D6
ENS _GND LED6
V_IN>V_f(max)+0.2 V, V_f = LED forward drop
Figure 3. High efficiency current sink