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参数资料
| 型号： | A8431EEHTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 9/11页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR WHITE BCKLGHT 6-MLP |
| 标准包装： | 1 |
| 恒定电流： | 是 |
| 拓扑： | PWM，升压（升压） |
| 输出数： | 1 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 背光 |
| 类型 - 次要： | 白色 LED |
| 频率： | 1.2MHz |
| 电源电压： | 2.5 V ~ 10 V |
| 输出电压： | 32V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 6-WFDFN 裸露焊盘 |
| 供应商设备封装： | 6-MLP/DFN（2x3） |
| 包装： | 标准包装 |
| 工作温度： | -40°C ~ 85°C |
| 其它名称： | 620-1195-6 |
A8431
White LED Driver Constant Current
Step-up Converter
PWM Control . The control voltage, V C , also can be
generated by a filtered PWM signal, as shown in schematic
3. In this case, a 0% duty cycle (PWM = 0 V) corresponds
to full brightness and a 100% duty cycle causes the LED
6
VIN
L1
22 μH
1
SW
D1
V C (PMW)
OVP
current, I LOAD , to go to 0A.
By applying a PWM signal directly to the EN pin, the A8431
is turned on or off, and I LOAD is either full (as defined by
R1) or 0 A. By varying the duty cycle of the PWM signal, the
LED brightness can be controlled from off (0% duty cycle)
to full (100% duty cycle). The PWM frequency should be in
the range from 1 kHz to 10 kHz.
Li-ion
2.5 V to
4.2 V
1.0 μF
C1 A843 1
EN GND
4 2
Enable
R4
10 k Ω
5
FB
3
R2
5 k Ω
R3
90 k Ω
C3
100 nF
R1
6.3 Ω
C2
0.22 μF
Several other schemes are possible, for example, digitally
switching additional resistors across R1 to increase I LOAD .
In this case, R1 would be selected for the minimum desired
brightness.
Start-Up
Schematic 3. Dimming control with filtered PWM
To provide fast start-up operation, no soft start is
L1
22 μH
D1
implemented in the control circuit. At power-on, the bypass
capacitor, C1, is discharged, which means that the supply
must provide the in-rush current through the inductor, L1.
This can be reduced by modulating the feedback with a soft-start
circuit as shown in schematic 4. When power is first applied, the
capacitor C3 is discharged and pulls the FB pin high, reducing
the output drive to minimum. As C3 charges, when the bottom
Li-ion
2.5V to
4.2V
C1
1.0 μF
6
VIN
A843 1
EN GND
4 2
Enable
1
SW
OVP
FB
3
5
C3
2.2 nF
R2
1 k Ω
R3
5 k Ω
R1
6.3 Ω
C2
0.22 μF
drops below about 0.8 V, the feedback from the sense resistor,
R1, takes over full control of the output current.
Schematic 4. Soft start operation
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
8
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相关代理商/技术参数 |
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| A8435 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:High Efficiency Charge Pump White LED Driver |
| A8435EESTR-T | 功能描述:IC LED DRVR WHITE BCKLGHT 16-MLP RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 标准包装:1 系列:- 恒定电流:- 恒定电压:- 拓扑:PWM，切换式电容器（充电泵） 输出数:1 内部驱动器:是 类型 - 主要:背光 类型 - 次要:白色 LED 频率:642kHz 电源电压:2.7 V ~ 5.5 V 输出电压:5V 安装类型:表面贴装 封装/外壳:10-VFDFN 裸露焊盘 供应商设备封装:10-VSON 包装:剪切带 (CT) 工作温度:-30°C ~ 85°C 产品目录页面:1371 (CN2011-ZH PDF) 其它名称:BD1603NUV-E2CT |
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