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PDF A8434 Data sheet ( Hoja de datos )
| Número de pieza | A8434 | |
| Descripción | 6-Channel High Efficiency Charge Pump White LED Driver | |
| Fabricantes | Allegro MicroSystems | |
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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
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
D1
D2
D3
D4
D5
D6
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+ LED1
C1– LED2
C2+ A8434
LED3
C2–
ISET
LED4
ENM
LED5
ENS GND LED6
D1
D2
D3
D4
D5
D6
VIN>Vf(max)+0.2 V, Vf = LED forward drop
Figure 3. High efficiency current sink
1 page  
A8434
6-Channel High Efficiency Charge Pump
White LED Driver
100.0
95.0
90.0
85.0
80.0
75.0
70.0
65.0
60.0
55.0
2.7
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
2.7
Performance Characteristics
Tests performed using application circuit shown in figure 2
TA= 25°C, VIN= 3.6 V (unless otherwise noted)
Efficiency versus Supply Voltage
VIN falling, Vf = 3.4 V at 20 mA
Sub
Main
Main + Sub
3.1 3.5 3.9 4.3 4.7 5.1 5.5
VIN (V)
100.0
95.0
90.0
85.0
80.0 Sub
75.0
70.0
65.0
60.0
55.0
50.0
2.7
Efficiency versus Supply Voltage
VIN falling, Vf = 3.1 V at 10 mA
Main
Main + Sub
3.1 3.5 3.9 4.3 4.7
VIN (V)
5.1
Logic Level
RSET versus LED Current
30
VHI
VLO
25
RSET = 6.65 kΩ
20
RSET = 8.87 kΩ
15
10
3.1 3.5 3.9 4.3 4.7 5.1 5.5
VIN (V)
5
4 6 8 10 12 14 16
RSET (kΩ)
Dimming on ENM and ENS
Enable Pulses versus Total Current, LED1 through LED6
VENM and VENS
5.5
18
C1
ILED1-6
C2
t
Symbol Parameter Units/Division
C1 VENM 0.5 V
C2
ILED16
50 mA
t time 50 ms
Allegro MicroSystems, Inc.
5
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
5 Page 
A8434
6-Channel High Efficiency Charge Pump
White LED Driver
Package ES, 3 × 3 mm16-Pin QFN/MLP
3.15 .124
2.85 .112
16
All dimensions reference only, not for tooling use
(reference JEDEC MO-220WEED-4)
Dimensions in millimeters
U.S. Customary dimensions (in.) in brackets, for reference only
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
A Terminal #1 mark area
1A
2
B Exposed thermal pad (reference only, terminal #1
identifier appearance at supplier discretion)
C Reference land pattern layout (reference IPC7351
QFN50P300X300X80-17W4M); adjust as necessary to
meet application process requirements and PCB layout
tolerances; when mounting on a multilayer PCB, thermal
vias at the exposed thermal pad land can improve thermal
dissipation (reference EIA/JEDEC Standard JESD51-5)
0.90 .035
NOM
0.30 .012
NOM
0.50 .020
16 NOM
16X
0.08 [.003] C
16X
0.30
0.18
.012
.007
0.10 [.004] M C A B
0.05 [.002] M C
0.50 .020
1.70 .067
NOM
C
12X 0.20 .008
MIN
1
1.70 .067
NOM
3.10 .122
NOM
0.50 .020
0.30 .012
2
1
B
4X 0.20 .008
MIN
1.70 .067
NOM
3.10 .122
NOM
4X 0.20 .008
MIN
16
0.23 x 0.23 .009 x .009
REF
A
B
3.15 .124
2.85 .112
SEATING C
PLANE
0.80 .031
0.70 .028
0.20 .008
REF
0.05 .002
0.00 .000
1.70 .067
NOM
Copyright ©2006, Allegro MicroSystems, Inc.
The products described here are manufactured under one or more U.S. patents or U.S. patents pending.
Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detail specifications as may be required to per-
mit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the
information being relied upon is current.
Allegro’s products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the
failure of that life support device or system, or to affect the safety or effectiveness of that device or system.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use;
nor for any infringement of patents or other rights of third parties which may result from its use.
For the latest version of this document, visit our website:
www.allegromicro.com
Allegro MicroSystems, Inc.
11
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
11 Page | ||
| Páginas | Total 11 Páginas | |
| PDF Descargar | [ Datasheet A8434.PDF ] | |
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