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參數(shù)資料
| 型號： | LM2707 |
| 廠商： | National Semiconductor Corporation |
| 元件分類： | LED驅(qū)動器 |
| 英文描述： | Inductive-Boost Series LED Driver with Programmable Oscillator Frequency |
| 中文描述： | 電感式升壓系列LED具有可編程振蕩器頻率驅(qū)動 |
| 文件頁數(shù)： | 10/19頁 |
| 文件大小： | 1039K |
| 代理商： | LM2707 |
Simplified Switching Circuit
Product Description
OVERVIEW
The LM2707 is a magnetic switch-mode boost converter that
has been designed specifically for driving white LEDs. The
device is an asynchronous boost regulator that uses a low-
resistance internal NFET power transistor and an external
rectifier diode. An internal high-power gate driver quickly
turns the power switch ON and OFF.
Operation of the LM2707 can be best understood by refer-
ring to the block diagram of
Figure 1
, the simplified switching
circuit in
Figure 2
, and the switching waveforms in
Figure 3
.
The part regulates the feedback voltage with pulse-
frequency-modulated (PFM) control. The key blocks in this
control circuit are the R-S latch, the oscillator, and the feed-
back error amplifier. Several sense-and-control circuit
blocks, including the oscillator and the error amplifier, are
inputs to the R-S latch. The output of the R-S latch is the
control signal for the power transistor gate driver. The power
transistor turns ON and OFF at a frequency and duty cycle
that is generated by the oscillator. The oscillator frequency
can be programmed with an external capacitor (C
). The
part switches continuously until one of the LM2707 sense
circuits asserts a reset signal on the R-S latch.
The error amplifier resets the R-S latch when the output
feedback voltage is above the 515mV (typ.) reference volt-
age. The part will idle in a low-power state until the feedback
voltage falls below the reference voltage. At this point, the
oscillator signal again becomes the output signal of the R-S
latch, and switching resumes.
In addition to the feedback circuit, a few other internal pro-
tection and control circuits stop switching by overriding the
oscillator signal at the R-S latch. A current limit circuit brings
switching to a halt when current through the power switch
becomes excessive. Similar interrupts in switching are trig-
gered by an over-voltage protection circuit on the output and
an under-voltage lockout circuit on the input. An external
shutdown signal can also be applied to place the LM2707 in
a low-power shutdown mode.
PROGRAMMABLE OSCILLATOR
The LM2707 contains an oscillator with an internally fixed
duty cycle. The frequency of the oscillator is programmed
externally with capacitor C
X
. The oscillator frequency is:
20099228
FIGURE 2. LM2707 Simplified Switching Circuit
20099229
FIGURE 3. C
X
Oscillator Waveform and Power Switch
Operation
L
www.national.com
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| LM2707MFX | Inductive-Boost Series LED Driver with Programmable Oscillator Frequency |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2707MF | 制造商:Texas Instruments 功能描述:LED DRIVER WHITE POWERWISE SOT-23-8 |
| LM2707MF/NOPB | 功能描述:IC LED DRVR WHITE BCKLGT SOT23-8 RoHS:是 類別:集成電路 (IC) >> PMIC - LED 驅(qū)動器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 恒定電流:- 恒定電壓:- 拓?fù)?PWM，切換式電容器（充電泵） 輸出數(shù):1 內(nèi)部驅(qū)動器:是 類型 - 主要:背光 類型 - 次要:白色 LED 頻率:642kHz 電源電壓:2.7 V ~ 5.5 V 輸出電壓:5V 安裝類型:表面貼裝 封裝/外殼:10-VFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:10-VSON 包裝:剪切帶 (CT) 工作溫度:-30°C ~ 85°C 產(chǎn)品目錄頁面:1371 (CN2011-ZH PDF) 其它名稱:BD1603NUV-E2CT |
| LM2707MFX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Inductive-Boost Series LED Driver with Programmable Oscillator Frequency |
| LM2707MFX/NOPB | 功能描述:IC LED DRVR WHITE BCKLGT SOT23-8 RoHS:是 類別:集成電路 (IC) >> PMIC - LED 驅(qū)動器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 恒定電流:- 恒定電壓:- 拓?fù)?PWM，切換式電容器（充電泵） 輸出數(shù):1 內(nèi)部驅(qū)動器:是 類型 - 主要:背光 類型 - 次要:白色 LED 頻率:642kHz 電源電壓:2.7 V ~ 5.5 V 輸出電壓:5V 安裝類型:表面貼裝 封裝/外殼:10-VFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:10-VSON 包裝:剪切帶 (CT) 工作溫度:-30°C ~ 85°C 產(chǎn)品目錄頁面:1371 (CN2011-ZH PDF) 其它名稱:BD1603NUV-E2CT |
| LM2708HTLX-1.57/NOPB | 制造商:Texas Instruments 功能描述: |
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