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參數資料
| 型號： | A8430EEK-T |
| 廠商： | Allegro MicroSystems, Inc. |
| 元件分類： | LED驅動器 |
| 英文描述： | White LED Driver Constant Current Step-up Converter |
| 中文描述： | 白光LED驅動恒流升壓轉換器 |
| 文件頁數： | 7/10頁 |
| 文件大小： | 329K |
| 代理商： | A8430EEK-T |
7
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
D
2
A8430
White LED Driver Constant Current Step-up Converter
Schematic 3. Dimming control with filtered PWM
A843
VIN
SW
EN
GND
FB
Li-ion
2.5 V to
4.2 V
C1
1 μF
L1
22 μH
D1
C2
0.22 μF
R1
6.3
V
C
(PMW)
R3
90 k
R2
5 k
Enable
R4
10 k
C3
100 nF
Schematic 4. Soft start operation
A8430
VIN
SW
EN
GND
FB
Li-ion
2.5V to
4.2V
C1
1μF
L1
22μH
D1
C2
0.22μF
R1
6.3
R3
5k
R2
1k
Enable
C3
2.2 nF
By applying a PWM signal directly to the EN pin, the A8430
is turned on or off, and I
LOAD
is either full (as defined by
R1) or zero. 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.
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.
Soft Start-Up
To provide fast start-up operation, no soft start is
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.
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 drops below about 0.8 V, the feedback from
the sense resistor (R1) takes over full control of the output
current.
Overvoltage Protection
An overvoltage event can occur when the LEDs become
disconnected or fail in an open state. In these cases, the
current flow through the sense resistor becomes zero, thus
the feedback voltage becomes zero. The A8430 compensates
by increasing the on time of the switch, which increases the
output voltage.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| A8430EEKTR-T | 功能描述:IC LED DRVR WHITE BCKLGHT 5-MLPD RoHS:是 類別:集成電路 (IC) >> PMIC - LED 驅動器 系列:- 標準包裝:1 系列:- 恒定電流:- 恒定電壓:- 拓撲:PWM，切換式電容器（充電泵） 輸出數:1 內部驅動器:是 類型 - 主要:背光 類型 - 次要:白色 LED 頻率:642kHz 電源電壓:2.7 V ~ 5.5 V 輸出電壓:5V 安裝類型:表面貼裝 封裝/外殼:10-VFDFN 裸露焊盤 供應商設備封裝:10-VSON 包裝:剪切帶 (CT) 工作溫度:-30°C ~ 85°C 產品目錄頁面:1371 (CN2011-ZH PDF) 其它名稱:BD1603NUV-E2CT |
| A8430EEKTR-T | 制造商:Allegro MicroSystems 功能描述:DC-DC Converter IC |
| A8431 | 制造商:ALLEGRO 制造商全稱:Allegro MicroSystems 功能描述:White LED Driver Constant Current Step-up Converter |
| A8431EEH-T | 制造商:ALLEGRO 制造商全稱:Allegro MicroSystems 功能描述:White LED Driver Constant Current Step-up Converter |
| A8431EEHTR-T | 功能描述:IC LED DRVR WHITE BCKLGHT 6-MLP RoHS:是 類別:集成電路 (IC) >> PMIC - LED 驅動器 系列:- 標準包裝:1 系列:- 恒定電流:- 恒定電壓:- 拓撲:PWM，切換式電容器（充電泵） 輸出數:1 內部驅動器:是 類型 - 主要:背光 類型 - 次要:白色 LED 頻率:642kHz 電源電壓:2.7 V ~ 5.5 V 輸出電壓:5V 安裝類型:表面貼裝 封裝/外殼:10-VFDFN 裸露焊盤 供應商設備封裝:10-VSON 包裝:剪切帶 (CT) 工作溫度:-30°C ~ 85°C 產品目錄頁面:1371 (CN2011-ZH PDF) 其它名稱:BD1603NUV-E2CT |
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