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参数资料
| 型号： | MIC2287-34YML TR |
| 厂商： | Micrel Inc |
| 文件页数： | 7/10页 |
| 文件大小： | 0K |
| 描述： | IC LED DRIVER WHITE BCKLGT 8-MLF |
| 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，闪灯/白光 |
| 类型 - 次要： | 白色 LED |
| 频率： | 1.05MHz ~ 1.35MHz |
| 电源电压： | 2.5 V ~ 10 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-VFDFN 裸露焊盘，8-MLF? |
| 供应商设备封装： | 8-MLF?（2x2） |
| 包装： | 标准包装 |
| 工作温度： | -40°C ~ 125°C |
| 产品目录页面： | 1082 (CN2011-ZH PDF) |
| 其它名称： | 576-1726-6 |
MIC2287
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-ef?ciency 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 ?ltered PWM signal. The advantage of this ap-
proach is a high frequency PWM signal (>10kHz)
that can be used to control LED intensity.
V IN
Micrel, Inc.
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 speci?ed 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.
V IN
VIN SW
EN FB
GND OVP
Figure 3. MLF? Package OVP Circuit
V IN
VIN
SW
VIN
SW
PWM
EN
FB
EN
FB
5.11k
GND
GND
V IN
Figure 1. PWM Dimming Method
Figure 4. Thin SOT-23 Package OVP Circuit
Start-Up and Inrush Current
VIN
EN
SW
FB
GND
5.11k
49.9k
DC
Equivalent
During start-up, inrush current of approximately double the
nominal current ?ows 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.
V IN
GND
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 over-
voltage protection (OVP). The extra pins of the 8-lead 2mm
× 2mm MLF? package allow a dedicated OVP monitor with
C SS
2200pF
VIN SW
EN FB
R
10k
Figure 5. Soft-Start Circuit
July 2005
7
M9999-070105
相关PDF资料 |
PDF描述 |
|---|---|
| MIC2289C-34YD6 TR | IC LED DRIVR WHITE BCKLGT TSOT-6 |
| MIC2291YD5 TR | IC LED DRIVER PHOTO FLASH TSOT-5 |
| MIC2293-15YML TR | IC LED DRIVER WHITE BCKLGT 8-MLF |
| MIC2293C-34YML TR | IC LED DRIVER WHITE BCKLGT 8-MLF |
| MIC2297-42YML TR | IC LED DRIVR WHITE BCKLGT 10-MLF |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC2287-3-LED-EV | 功能描述:MIC2287 1, Non-Isolated Output LED Driver Evaluation Board 制造商:microchip technology 系列:- 零件状态:无货 电流 - 输出/通道:- 输出和类型:1，非隔离 电压 - 输出:- 特性:- 电压 - 输入:2.5 V ~ 10 V 所含物品:板 使用的 IC/零件:MIC2287 标准包装:1 |
| MIC2287-6-LED-EV | 功能描述:MIC2287 1, Non-Isolated Output LED Driver Evaluation Board 制造商:microchip technology 系列:- 零件状态:无货 电流 - 输出/通道:- 输出和类型:1，非隔离 电压 - 输出:- 特性:- 电压 - 输入:2.5 V ~ 10 V 所含物品:板 使用的 IC/零件:MIC2287 标准包装:1 |
| MIC2287BD5 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:1.2MHz PWM White LED Driver with OVP in 2mm 】 2mm MLF⑩ and Thin SOT-23 |
| MIC2287BD5 TR | 功能描述:IC LED DRVR WHT BCKLGT TSOT23-5 RoHS:否 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 |
| MIC2287C | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:1.2MHz PWM White LED Driver with OVP in 2mm × 2mm MLF and Thin SOT-23 |
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