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參數(shù)資料
| 型號： | MIC2287-24BML |
| 廠商： | MICREL INC |
| 元件分類： | 顯示驅(qū)動器 |
| 英文描述： | Replaced by PTH05060W : |
| 中文描述： | LED DISPLAY DRIVER, DSO8 |
| 封裝： | 2 X 2 MM, MLF-8 |
| 文件頁數(shù)： | 7/10頁 |
| 文件大?。?/td> | 111K |
| 代理商： | MIC2287-24BML |
August 2004
7
M0510-081104
MIC2287
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
MIC2287 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
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
MIC2287 through a series resistor as shown in
Figure 2. The LED intensity (current) can be dy-
namically 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 a high frequency PWM signal (>10kHz)
that can be used to control LED intensity.
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 case an
LED fails open, the sense resistor will pull the FB pin to
ground. This will cause the MIC2287 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 MIC2287 has 3
product options in the 8-lead 2mm
×
2mm MLF
with
overvoltage protection (OVP). The extra pins of the 8-lead
2mm
×
2mm MLF
package allow a dedicated OVP monitor
with options 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, as well as smallest
size and lowest cost. The OVP will clamp the output voltage
to within the specified limits. For the Thin SOT-23-5 package,
an OVP pin is not available. An external zener diode can be
connected from the output of the converter to FB pin as shown
in Figure 4. to implement similar protection.
VIN
EN
GND
SW
FB
OVP
V
IN
Figure 3. MLF
Package OVP Circuit
VIN
EN
SW
FB
GND
V
IN
5.11k
Figure 4. Thin SOT-23 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 5 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
SW
FB
C
2200pF
R
10k
GND
V
IN
Figure 5. Soft-Start Circuit
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MIC2287-34BML | Replaced by PTH05060W : |
| MIC2288YD5 | 1A 1.2 MHZ PWM BOOST CONVERTER IN THIN SOT 23 AND 2 X MLF |
| MIC2288BD5 | 1A 1.2 MHZ PWM BOOST CONVERTER IN THIN SOT 23 AND 2 X MLF |
| MIC2288 | Replaced by PTH05060W : 2.5VOUT 8A 5V/3.3V-INPUT ADJUSTABLE ISR WITH SHORT-CIRCUIT PROTECTION 14-SIP MODULE -40 TO 85 |
| MIC2288BML | Replaced by PTH05060W : |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MIC2287-24BML 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(biāo)準(zhǔn)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(yīng)商設(shè)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 |
| MIC2287-24YML | 制造商:Rochester Electronics LLC 功能描述: 制造商:RF Micro Devices Inc 功能描述: 制造商:Micrel Inc 功能描述: |
| MIC2287-24YML 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(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
| MIC2287-24YML-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(guān)） 8-MLF?（2x2） 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）:2.5V 電壓 -?供電（最高）:10V 電壓 - 輸出:24V 電流 - 輸出/通道:750mA（開關(guān)） 頻率:1.2MHz 調(diào)光:模擬，PWM 應(yīng)用:背光，照相機閃光燈 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(yīng)商器件封裝:8-MLF?（2x2） 標(biāo)準(zhǔn)包裝:1 |
| MIC2287-34BML | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:1.2MHz PWM White LED Driver with OVP in 2mm 】 2mm MLF⑩ and Thin SOT-23 |
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