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参数资料
| 型号： | LDS8720 |
| 厂商： | IXYS |
| 文件页数： | 6/10页 |
| 文件大小： | 0K |
| 描述： | IC LED DRIVER PWM 25MA 8TDFN |
| 标准包装： | 1 |
| 拓扑： | PWM，升压（升压） |
| 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： | 700kHz |
| 电源电压： | 2.7 V ~ 5.5 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-WFDFN 裸露焊盘 |
| 供应商设备封装： | 8-TDFN |
| 包装： | 标准包装 |
| 工作温度： | -40°C ~ 85°C |
| 其它名称： | LDS8720DKR |
LDS8720
BLOCK DIAGRAM
Figure 2. LDS8720 Functional Block Diagram
BASIC OPERATION
At power-up, EN/PWM pin should be logic LOW. The
LDS8720 starts operating when EN/PWM pin is
asserted logic high. If the input voltage is sufficient to
regulate all LED currents, the device remains in
operating mode. The low dropout Current regulator
performs well at V OUT voltage up to 250 mV above
summary LED forward voltage significantly increasing
driver’s efficiency.
If the input voltage is insufficient or falls to a level
where the regulated currents cannot be maintained,
the Under-Voltage protection turns device off setting
it in shutdown mode.
The LDS8720 has soft start function that prevent high
input current spike at device’ wake-up.
The EN/PWM pin should be held low for more than
10 ms to completely turn device in low current
shutdown mode.
LED Current Setting
The maximum current sink value in the LEDS pin is
factory preset at 30 mA. An external resisror R FB
should be used to bypass current if more than one
string is connected. R FB = 0.25 V / (I x M – 0.03),
ohms, where 0.25 V is a feedback voltage, I – is
current value per string in ampers, and M is number
of strings connected in parallel.
Power dissipated at R FB is equal W = 0.0625/R FB ,
watt.
In case of three strings with 25 mA current per string
R FB = 0.25/(0.025 x 3 – 0.03) = 5.6 ? , and dissipated
power W = 0.0625/5.6 = 0.011 W.
The average LED string current that determines LED
brightness may be controlled applying PWM signal to
the EN/PWM pin. The maximum PWM frequency is
30 kHz, while frequiencies below 100 Hz are not
recommended to avoid visible LED flikering. Duty
cycle that determines average LED string current
may vary in the range from 5% to 100% at 1 kHz or
from 20% to 100% at 30 kHz with high linearity
current regulation.
Protection Mode
The output voltage V OUT is limited at about 36 V. This
is to prevent the output pin from exceeding its
absolute maximum rating if LED string is
disconnected or any LED.in string burns out creating
open circuitry.
If the die temperature exceeds +150°C, the driver will
enter a thermal protection shutdown mode. When the
device temperature drops by about 20°C, the device
will resume normal operation.
? 2011 IXYS Corp.
Characteristics subject to change without notice
6
Doc. No. 8720DS, Rev. N1.1
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| LDS8724 | 功能描述:LED照明驱动器 40 WLED driver Boost Converter RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| LDS8724008T2-200 | 制造商:IXYS 制造商全称:IXYS Corporation 功能描述:40 WLED Driver with Boost Converter |
| LDS8726 | 功能描述:LED照明驱动器 42 WLED driver Boost Converter RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| LDS8845-002-T2 | 功能描述:LED照明驱动器 4-Chan UL DropOut WLED Driver RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| LDS8846-002-T2 | 功能描述:LED照明驱动器 4-Chan UL DropOut WLED Driver RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
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