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参数资料
| 型号： | IRS25401SPBF |
| 厂商： | International Rectifier |
| 文件页数： | 13/20页 |
| 文件大小： | 0K |
| 描述： | IC LED CONS CURR CTRL 8SOIC |
| 标准包装： | 95 |
| 拓扑： | PWM，降压（降压） |
| 输出数： | 1 |
| 内部驱动器： | 无 |
| 类型 - 主要： | 通用 |
| 频率： | 500kHz |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOIC |
| 包装： | 管件 |
IRS254(0,1)(S)PbF
Watchdog Timer
Disable (ENN) Pin
During an open circuit condition, without the watchdog
HO
LO
timer, the HO output would remain high at all times and
the charge stored in the bootstrap capacitor C BOOT
would gradually discharge the floating power supply for
the high-side driver, which would then be unable to fully
switch on the upper MOSFET causing high losses. To
maintain sufficient charge on the bootstrap capacitor, a
watchdog timer has been implemented. In the
condition where V IFB remains below V IFBTH , the HO
output is driven low after 20 μ s and the LO output
forced high. This toggling of the outputs will last for
approximately 1 μ s to maintain and replenish sufficient
charge on C BOOT .
Fig.4 Illustration of Watchdog Timer
Bootstrap Capacitor and Diode
The bootstrap capacitor value needs to be selected so
that it maintains sufficient charge for at least the
approximately 20 μ s interval until the watchdog timer
allows the capacitor to recharge. If the capacitor value
is too small, it will discharge in less than 20 μ s. The
typical bootstrap capacitor is approximately 100 nF.
The bootstrap diode must be a fast recovery or ultrafast
The disable pin can be used for PWM dimming and
open-circuit protection. When the ENN pin is held
low, the chip remains in a fully functional state with no
alterations to the operating environment. To disable
the control feedback and regulation, a voltage greater
than V ENTH (approximately 2.5 V) needs to be applied
to the ENN pin. With the chip in a disabled state, HO
output will remain low, whereas the LO output will
remain high to prevent V S from floating, in addition to
maintaining charge on the bootstrap capacitor. The
threshold for disabling the IRS254(01,11) has been
set to 2.5 V to enhance noise immunity. This 2.5 V
threshold also provides compatibility for a drive signal
from a microcontroller.
Dimming Mode
To achieve dimming, a signal with constant frequency
and adjustable duty cycle can be fed into the ENN
pin. There is a direct linear relationship between the
average load current and duty cycle. If the ratio is
50%, 50% of the maximum set light output will be
realized. Likewise if the ratio is 30%, 70% of the
maximum set light output will be realized. A
sufficiently high frequency of the dimming signal must
be chosen to avoid noticeable flashing or “strobe
light” effect. A signal above 120Hz up to 5kHz is
sufficient.
The ENN pin logic is inverted to provide enable low
so that the default state is with the IC running.
The minimum amount of dimming achievable (light
output approaches 0%) will be determined by the “on”
time of the HO output, when in a fully functional
regulating state. To maintain reliable dimming, it is
recommended to keep the “off” time of the enable
signal at least 10 times that of the HO “on” time. For
example, if the application is running at 75 kHz with
an input voltage of 100 V and an output voltage of 20
V, the HO “on” time will be approximately 2.7 μs
according to standard buck topology theory. This will
set the minimum “off” time of the enable signal to 27
μs.
recovery component to maintain good efficiency. Since
the cathode of the bootstrap diode will be switching
between zero and to the high voltage bus, the reverse
Duty Cycle =
V out
V in
? 100 =
20 V
100 V
* 100 = 20 %
recovery time of this diode is critical. For additional
information concerning the bootstrap components, refer
to the Design Tip (DT 98-2), “Bootstrap Component
HO on time = 20 % * 1
75 kHz
≈ 2 . 7 μ s
Selection For Control ICs” at www.irf.com under Design
Support
www.irf.com
13
? 2010 International Rectifier
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相关代理商/技术参数 |
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|---|---|
| IRS25401STRPBF | 功能描述:LED照明驱动器 Hysteretic Buck LED Drvr 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 |
| IRS2540PbF | 功能描述:LED照明驱动器 200V HALF BRDG DRVR LED BUCK REGULATOR 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 |
| IRS2540PBF | 制造商:International Rectifier 功能描述:LED Driver IC 制造商:International Rectifier 功能描述:IC, LED CURRENT REGULATOR, BUCK, DIP-8 |
| IRS2540SPbF | 功能描述:LED照明驱动器 200V HALF BRDG DRVR LED BUCK REGULATOR 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 |
| IRS2540SPBF | 制造商:International Rectifier 功能描述:LED Driver IC 制造商:International Rectifier 功能描述:IC, LED CURRENT REGULATOR, BUCK, SOIC-8 |
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