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| 型号： | IRPLLED1 |
| 厂商： | International Rectifier |
| 文件页数： | 8/15页 |
| 文件大小： | 0K |
| 描述： | BOARD EVALUATION FOR IRS2540PBF |
| 标准包装： | 1 |
| 电流 - 输出 / 通道： | 1.5A |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 24V |
| 特点： | 可调光 |
| 输入电压： | 50 ~ 170V |
| 已供物品： | 板 |
| 已用 IC / 零件： | IRS2540PBF |
| 相关产品： | IRS2540PBF-ND - IC LED DRVR HP CONST CURR 8-DIP |
IRS254(0,1)(S)PbF
HO
LO
Watchdog Timer
During an open circuit condition, without the
watchdog 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 will be forced 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 chosen
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, the charge will dissipate in less
than 20 μ s. The typical bootstrap capacitor is
approximately 100 nF.
The bootstrap diode should be a fast recovery or
ultrafast recovery component to maintain good
Design Tip (DT 98-2), “Bootstrap Component
Selection For Control ICs” at www.irf.com under
Design Support
Disable (ENN) Pin
The disable pin can be used for 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(0,1) has been set to 2.5 V to enhance
immunity to any externally generated noise, or
application ground noise. This 2.5 V threshold also
makes it ideal to receive a drive signal from a local
microcontroller.
Dimming Mode
To achieve dimming, a signal with constant
frequency and set 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 flashing or “strobe light”
effect. A signal on the order of a few kHz should be
sufficient.
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 3.3 μs (one-fourth of
the period – see calculations below) according to
standard buck topology theory. This will set the
minimum “off” time of the enable signal to 33 μs.
efficiency. Since the cathode of the bootstrap diode
will be switching between zero and to the high
voltage bus, the reverse recovery time of this diode
Duty Cycle =
V out
V in
? 100 =
20 V
100 V
* 100 = 20 %
is of critical importance. For additional information
concerning the bootstrap components, refer to the
www.irf.com
HO on time = 20 % * 1
75 kHz
= 3 . 3 μ s
Page 8
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| IRPLLED1A | 功能描述:电源管理IC开发工具 Hi-Vlt DC-DC Buck Cnvr HBLED Cur Cntrl RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| IRPLLED5 | 制造商:International Rectifier 功能描述: |
| IRPLLED7 | 功能描述:IC MOSFET DRIVER RoHS:否 类别:集成电路 (IC) >> PMIC - MOSFET，电桥驱动器 - 外部开关 系列:* 标准包装:95 系列:- 配置:半桥 输入类型:PWM 延迟时间:25ns 电流 - 峰:1.6A 配置数:1 输出数:2 高端电压 - 最大（自引导启动）:118V 电源电压:9 V ~ 14 V 工作温度:-40°C ~ 125°C 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 产品目录页面:1282 (CN2011-ZH PDF) 其它名称:*LM5104M*LM5104M/NOPBLM5104M |
| IRPLLNR1 | 制造商:未知厂家 制造商全称:未知厂家 功能描述: |
| IRPLLNR2E | 功能描述:KIT BALLAST LINEAR INT 230VAC RoHS:否 类别:编程器，开发系统 >> 过时/停产零件编号 系列:- 标准包装:1 系列:- 类型:MCU 适用于相关产品:Freescale MC68HC908LJ/LK（80-QFP ZIF 插口） 所含物品:面板、缆线、软件、数据表和用户手册 其它名称:520-1035 |
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