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參數(shù)資料
| 型號： | LM2794TLX |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Current Regulated Switched Capacitor LED Supply with Analog and PWM Brightness Control |
| 中文描述： | SWITCHED CAPACITOR REGULATOR, 675 kHz SWITCHING FREQ-MAX, PBGA14 |
| 封裝： | CSP-14 |
| 文件頁數(shù)： | 9/16頁 |
| 文件大小： | 487K |
| 代理商： | LM2794TLX |
Functional Block Diagram
20028530
Application Information
CIRCUIT DESCRIPTION
The LM2794/5 is a 1.5x/1x CMOS charge pump with four
matched constant current outputs, each capable of driving
up to 20mA through White LEDs. This device operates over
the extended Li-Ion battery range from 2.7V to 5.5V. The
LM2794/5 has four regulated current sources connected to
the device’s 1.5x charge pump output (P
OUT
). At input volt-
ages below 4.7V (typ.), the charge-pump provides the
needed voltage to drive high forward voltage drop White
LEDs. It does this by stepping up the P
OUT
voltage 1.5 times
the input voltage. The charge pump operates in Pass Mode,
providing a voltage on P
OUT
equal to the input voltage, when
the input voltage is at or above 4.7V (typ.). The device can
drive up to 80mA through any combination of LEDs con-
nected to the constant current outputs D
1
-D
4
.
To set the LED drive current, the device uses a resistor
connected to the I
SET
pin to set a reference current. This
reference current is then multiplied and mirrored to each
constant current output. The LED brightness can then be
controlled by analog and/or digital methods. Applying an
analog voltage in the range of 0V to 3.0V to the Brightness
pin (BRGT) adjusts the dimming profile of the LEDs. The
digital technique uses a PWM (Pulse Width Modulation)
signal applied to the Shutdown pin (SD). (see
I
SET
and
BRGT PINS
section).
SOFT START
Soft start is implemented internally by ramping the reference
voltage more slowly than the applied voltage. During soft
start, the current through the LED outputs will ramp up in
proportion to the rate that the reference voltage is being
ramped up.
L
www.national.com
9
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| LM2794BL | Current Regulated Switched Capacitor LED Supply with Analog and PWM Brightness Control |
| LM2794BLX | Current Regulated Switched Capacitor LED Supply with Analog and PWM Brightness Control |
| LM2794TL | Current Regulated Switched Capacitor LED Supply with Analog and PWM Brightness Control |
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| LM27952 | White LED Adaptive 1.5X/1X Switched Capacitor Current Driver |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2794TLX/NOPB | 功能描述:LED照明驅(qū)動器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
| LM2795 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述: |
| LM27951 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:White LED Adaptive 1.5X/1X Switched Capacitor Current Driver |
| LM27951SD | 功能描述:LED照明驅(qū)動器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
| LM27951SD/NOPB | 功能描述:LED照明驅(qū)動器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
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