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參數(shù)資料
| 型號： | MIC2289-34BML |
| 廠商： | MICREL INC |
| 元件分類： | 顯示驅(qū)動器 |
| 英文描述： | 2mm 】 2mm White LED Driver with Internal Schottky Diode and OVP |
| 中文描述： | LED DISPLAY DRIVER, DSO8 |
| 封裝： | 2 X 2 MM, MLF-8 |
| 文件頁數(shù)： | 7/9頁 |
| 文件大?。?/td> | 88K |
| 代理商： | MIC2289-34BML |
August, 2004
7
M9999-081104
MIC2289
Micrel
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 on EN pin as shown in Figure 1. The
MIC2289 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 cycle of the PWM signal. Typical
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
MIC2289 through a series resistor as shown in
Figure 2. The LED current is decreased propor-
tionally with the amplitude of the control voltage.
The LED intensity (current) can be dynamically
varied applying a DC voltage to the FB pin. The DC
voltage can come from a DAC signal, or a filtered
PWM signal . The advantage of this approach is
that a high frequency PWM signal (>10kHz) can be
used to control LED intensity.
PWM
VIN
EN
SW
FB
OUT
GND
V
IN
Figure 1. PWM Dimming Method
VIN
EN
SW
FB
OUT
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 case an
LED fails open, the sense resistor will pull the FB pin to
ground. This will cause the MIC2289 to switch with a high
duty-cycle, resulting in output overvoltage. This may cause
the SW pin voltage to exceed its maximum voltage rating,
possibly damaging the IC and the external components. To
ensure the highest level of protection, the MIC2289 has 3
product options in the 2mm
×
2mm MLF
-8 with overvoltage
protection, OVP. The extra pins of the 2mm
×
2mm
MLF
-8 package allow a dedicated OVP monitor with op-
tions for 15V, 24V, or 34V (see Figure 3). The reason for the
three OVP levels is to let users choose the suitable level of
OVP for their application. For example, a 3-LED application
would typically see an output voltage of no more than 12V, so
a 15V OVP option would offer a suitable level of protection.
This allows the user to select the output diode and capacitor
with the lowest voltage ratings, therefore smallest size and
lowest cost. The OVP will clamp the output voltage to within
the specified limits.
VIN
EN
GND
SW
FB
OUT
V
IN
Figure 3. MLF
Package OVP Circuit
Start-Up and Inrush Current
During start-up, inrush current of approximately double the
nominal current flows to set up the inductor current and the
voltage on the output capacitor. If the inrush current needs to
be limited, a soft-start circuit similar to Figure 4 could be
implemented. The soft-start capacitor, C
SS
, provides over-
drive to the FB pin at start-up, resulting in gradual increase of
switch duty cycle and limited inrush current.
VIN
EN
10k
2200pF
SW
OUT
FB
C
SS
R
GND
V
IN
Figure 4. One of Soft-Start Circuit
相關PDF資料 |
PDF描述 |
|---|---|
| MIC2289-34YML | 2mm 】 2mm White LED Driver with Internal Schottky Diode and OVP |
| MIC2290YML | 2mm 】 2mm PWM Boost Regulator with Internal Schotty Diode |
| MIC2290 | Replaced by PTH05060W : |
| MIC2290BML | Replaced by PTH05060W : |
| MIC2295 | High Power Density 1.2A Boost Regulator |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MIC2289-34BML TR | 功能描述:IC LED DRIVER WHITE BCKLGT 8-MLF RoHS:否 類別:集成電路 (IC) >> PMIC - LED 驅(qū)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(shù):1 內(nèi)部驅(qū)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(chǎn)品目錄頁面:1371 (CN2011-ZH PDF) 其它名稱:BD1603NUV-E2CT |
| MIC2289-34YML | 制造商:Rochester Electronics LLC 功能描述: 制造商:RF Micro Devices Inc 功能描述: |
| MIC2289-34YML TR | 功能描述:LED照明驅(qū)動器 2x2mm White LED Driver w/ 34V 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 |
| MIC2289-34YMLTR | 制造商:Micrel 功能描述:LED Driver 3.3V/5V/9V |
| MIC2289-34YML-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 750mA（開關） 8-MLF?（2x2） 制造商:microchip technology 系列:- 包裝:剪切帶（CT） 零件狀態(tài):有效 類型:DC DC 穩(wěn)壓器 拓撲:升壓（升壓） 內(nèi)部開關:是 輸出數(shù):1 電壓 - 供電（最低）:2.5V 電壓 -?供電（最高）:10V 電壓 - 輸出:34V 電流 - 輸出/通道:750mA（開關） 頻率:1.2MHz 調(diào)光:模擬，PWM 應用:背光 工作溫度:-40°C ~ 125°C （TJ） 安裝類型:表面貼裝 封裝/外殼:8-VFDFN 裸露焊盤，8-MLF? 供應商器件封裝:8-MLF?（2x2） 標準包裝:1 |
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