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參數(shù)資料
| 型號： | MIC3287YD5 |
| 廠商： | MICREL INC |
| 元件分類： | 顯示驅(qū)動器 |
| 英文描述： | 1.2MHz PWM White LED Driver with OVP in Thin SOT-23 and 2mm x 2mm MFL |
| 中文描述： | LED DISPLAY DRIVER, PDSO5 |
| 封裝： | LEAD FREE, MO193, SOT23, 5 PIN |
| 文件頁數(shù)： | 7/9頁 |
| 文件大?。?/td> | 342K |
| 代理商： | MIC3287YD5 |
January 2006
7
M9999-010306
MIC3287
Micrel, Inc.
Dimming Control
There are two techniques for dimming control. One is PWM
dimming, and the other is continuous dimming.
1. PWM dimming control is implemented by applying
a PWM signal to the EN pin, as shown in Figure
1. The MIC3287 is turned on and off by the PWM
signal. With this method, the LEDs operate with
either zero or full current. The average LED current
is increased proportionally to the duty-cycle of the
PWM signal. This technique has high-efficiency
because the IC and the LEDs consume no current
during the off time of the PWM signal. Typical PWM
frequency should be between 100Hz and 10kHz.
2. Continuous dimming control is implemented by
applying a DC control voltage to the FB pin of
the MIC3287 through a series resistor, as shown
in Figure 2. The LED intensity (current) can be
dynamically varied with the applied DC control
voltage. The DC voltage can come from a DAC
signal, or a filtered PWM signal. The advantage
of the filtered PWM signal approach is a high
frequency PWM signal (>10kHz) can be used to
control LED intensity (current).
PWM
VIN
EN
SW
FB
GND
V
IN
Figure 1. PWM Dimming Method
VIN
EN
SW
FB
5.11k
49.9k
GND
DC
Equivalent
V
IN
Figure 2. Continuous Dimming
Open-Circuit Protection
If the LEDs are disconnected from the circuit, or in the case
that an LED fails, the sense resistor will then pull the FB pin to
ground. This will cause the MIC3287 to switch with a high duty-
cycle, resulting in output over-voltage. This may cause the SW
pin voltage to exceed its maximum voltage rating, damaging
the IC and the external components. To ensure the highest
level of protection, the MIC3287 has buit-in 24V over-voltage
protection functionality in the TSOT-23-6 pin and 8-pin MLF
package options. The OVP will clamp the output voltage to
within the specified limits.
Start-Up and Inrush Current
If the inrush current needs to be limited, a soft-start circuit, simi-
lar to Figure 3, could be implemented. The soft-start capacitor,
C
SS
, provides overdrive to the FB pin at start-up, resulting in
gradual increase of switch duty cycle and limited in rush current.
VIN
EN
SW
FB
C
SS
2200pF
R
10k
GND
V
IN
Figure 3. Soft-Start Circuit
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MIC3287YD5 TR | 功能描述:LED照明驅(qū)動器 2x2mm White LED Driver w/ 24V OVP (Lead Free) RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:SO-16N |
| MIC3287YD5-TR | 功能描述:LED 驅(qū)動器 IC 1 輸出 DC DC 穩(wěn)壓器 升壓（升壓） 模擬，PWM 調(diào)光 350mA（開關(guān)） TSOT-23-5 制造商:microchip technology 系列:- 包裝:剪切帶（CT） 零件狀態(tài):停產(chǎn) 類型:DC DC 穩(wěn)壓器 拓撲:升壓（升壓） 內(nèi)部開關(guān):是 輸出數(shù):1 電壓 - 供電（最低）:2.8V 電壓 -?供電（最高）:6.5V 電壓 - 輸出:36V 電流 - 輸出/通道:350mA（開關(guān)） 頻率:1.2MHz 調(diào)光:模擬，PWM 應(yīng)用:背光 工作溫度:-40°C ~ 125°C （TJ） 安裝類型:表面貼裝 封裝/外殼:SOT-23-5 細型，TSOT-23-5 供應(yīng)商器件封裝:TSOT-23-5 標準包裝:1 |
| MIC3289 | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:1.2MHz PWM White LED Driver with Internal Schottky Diode and True 1-Wire Digital Control |
| MIC3289_0706 | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:1.2MHz PWM White LED Driver with Internal Schottky Diode and True 1-Wire Digital Control |
| MIC3289-16ML | 制造商:RF Micro Devices Inc 功能描述: |
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