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| 型号： | CAT4240TD-GT3 |
| 厂商： | ON Semiconductor |
| 文件页数： | 7/12页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR WHITE BCKLGHT TSOT-5 |
| 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 |
| 类型 - 次要： | 白色 LED |
| 频率： | 800kHz ~ 1.3MHz |
| 电源电压： | 2.8 V ~ 5.5 V |
| 输出电压： | 38V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SOT-23-5 细型，TSOT-23-5 |
| 供应商设备封装： | TSOT-23-5 |
| 包装： | 标准包装 |
| 工作温度： | -40°C ~ 85°C |
| 产品目录页面： | 805 (CN2011-ZH PDF) |
| 其它名称： | CAT4240TD-GT3DKR |
CAT4240
Device Operation
R1 +
current
The CAT4240 is a fixed frequency (1 MHz), low noise,
inductive boost converter that provides a constant current
with excellent line and load regulation. The device uses a
high-voltage CMOS power switch between the SW pin and
ground to energize the inductor. When the switch is turned
off, the stored energy in the inductor is released into the load
via the Schottky diode.
The on/off duty cycle of the power switch is internally
adjusted and controlled to maintain a constant regulated
voltage of 0.3 V across the feedback resistor connected to the
feedback pin (FB). The value of the resistor sets the LED
current accordingly (0.3 V/R 1 ).
During the initial power ? up stage, the duty cycle of the
internal power switch is limited to prevent excessive in ? rush
currents and thereby provide a “soft ? start” mode of
operation.
Application Information
External Component Selection
Capacitors
The CAT4240 only requires small ceramic capacitors of
4.7 m F on the inductor input, 1 m F on the VIN pin and 1 m F
on the output. Under normal condition, a 4.7 m F input
capacitor is sufficient. For applications with higher output
power, a larger input capacitor of 10 m F may be appropriate.
X5R and X7R capacitor types are ideal due to their stability
across temperature range.
Inductor
A 47 m H inductor is recommended for most of the
CAT4240 applications. In cases where the efficiency is
critical, inductances with lower series resistance are
preferred. Inductors with current rating of 800 mA or higher
are recommended for most applications. Sumida
CDRH6D28 ? 470 47 m H inductor has a rated current of
800 mA and a series resistance (D.C.R.) of 176 m W typical.
When the inductor is connected to a 9 V supply or higher,
the CAT4240 can drive 6 LEDs in series at 300 mA
delivering a total power of 6 Watts into the load. A separate
5 V supply voltage is connected to the VIN pin.
In the event of an “Open LED” fault condition, where the
feedback control loop becomes open, the output voltage will
continue to increase. Once this voltage exceeds 40 V, an
internal protection circuit will become active and place the
device into a very low power safe operating mode.
Thermal overload protection circuitry has been included
to prevent the device from operating at unsafe junction
temperatures above 150 ° C. In the event of a thermal
overload condition the device will automatically shutdown
and wait till the junction temperatures cools to 130 ° C before
normal operation is resumed.
forward voltage should be as low as possible. The response
time is also critical since the driver is operating at 1 MHz.
Central Semiconductor Schottky rectifier CMSH1 ? 40 (1 A
rated) is recommended for most applications.
LED Current Setting
The LED current is set by the external resistor R1
connected between the feedback pin (FB) and ground. The
formula below gives the relationship between the resistor
and the current:
0.3 V
LED
Table 5. RESISTOR R1 AN D LED CURRENT
LED Current (mA) R1 ( W )
20 15
Schottky Diode
The current rating of the Schottky diode must exceed the
peak current flowing through it. The Schottky diode
performance is rated in terms of its forward voltage at a
given current. In order to achieve the best efficiency, this
http://onsemi.com
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25
30
100
300
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相关代理商/技术参数 |
参数描述 |
|---|---|
| CAT4240TD-GT3 | 制造商:ON Semiconductor 功能描述:IC LED DRIVER BOOST TSOT-23-5 制造商:ON Semiconductor 功能描述:IC, LED DRIVER, BOOST, TSOT-23-5 |
| CAT-42506 | 制造商:Thomas & Betts 功能描述:1/4' YELLOW 6 PCS. PER BAG |
| CAT4254VP2-GT3 | 制造商:Catalyst Semiconductor 功能描述: 制造商:ON Semiconductor 功能描述: |
| CAT431L | 制造商:CATALYST 制造商全称:Catalyst Semiconductor 功能描述:Low-Voltage Adjustable Precision Voltage Reference |
| CAT431LEUK-TE7 | 功能描述:基准电压& 基准电流 1.24V .5% RoHS:否 制造商:STMicroelectronics 产品:Voltage References 拓扑结构:Shunt References 参考类型:Programmable 输出电压:1.24 V to 18 V 初始准确度:0.25 % 平均温度系数（典型值）:100 PPM / C 串联 VREF - 输入电压（最大值）: 串联 VREF - 输入电压（最小值）: 分流电流（最大值）:60 mA 最大工作温度:+ 125 C 封装 / 箱体:SOT-23-3L 封装:Reel |
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