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參數資料
| 型號： | LM2795 |
| 文件頁數： | 1/14頁 |
| 文件大小： | 373K |
| 代理商： | LM2795 |
LM2794/LM2795
Current Regulated Switched Capacitor LED Supply with
Analog Brightness Control
General Description
The LM2794/95 is a fractional CMOS charge-pump and
regulator that provides four regulated current sources. It
accepts an input voltage range from 2.7V to 5.5V and main-
tains a constant current determined by an external sense
resistor.
The LM2794/5 delivers up to 80mAof load current to accom-
modate four White LEDs. The switching frequency is
325kHz. (min.) to keep the conducted noise spectrum away
from sensitive frequencies within portable RF devices. Maxi-
mum operating current is 8.2mA (unloaded) and the maxi-
mum shutdown current is only 5μA. If not all output pins are
used, leave pin(s) unconnected.
Brightness can be controlled by both linear and PWM tech-
niques. A voltage between 0V and 3.0V may be applied to
the BRGT pin to vary the current over more than a 5 to 1
ratio. Output current will linearly track the voltage applied to
the BRGT pin. Alternatively, a PWM signal can be applied to
the SD pin to vary the perceived brightness of the LED. The
SD pin reduces the operating current to 5μA (max.) The
LM2794 uses an active-low shutdown level, and the LM2795
uses an active-high shutdown level.
The LM2794/95 is available in a micro SMD-14 CSP pack-
age.
Features
n
Regulated I
OUT
with
±
0.5% matching between any two
outputs
n
High efficiency 3/2 boost function
n
Drives one, two, three or four white LEDs
n
2.7V to 5.5V Input Voltage
n
Up to 80mA output current
n
Soft start limits inrush current
n
Analog brightness control
n
Active-low or high shutdown input (’94/95)
n
Very small solution size and no inductor
n
5μA (max.) shutdown current
n
325kHz switching frequency (min.)
n
Linear regulation generates predictable noise spectrum
n
micro SMD-14 package: 2.08mm X 2.403mm X
0.845mm
Applications
n
White LED Display Backlights
n
White LED Keypad Backlights
n
1-Cell Li-Ion battery-operated equipment including
PDAs, hand-held PCs, cellular phones
n
Flat Panel Displays
Basic Application Circuit
20028503
September 2002
L
C
2002 National Semiconductor Corporation
DS200285
www.national.com
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相關代理商/技術參數 |
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| 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: 安裝風格:SMD/SMT 封裝 / 箱體:SO-16N |
| LM27951SD/NOPB | 功能描述:LED照明驅動器 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: 安裝風格:SMD/SMT 封裝 / 箱體:SO-16N |
| LM27951SDX | 功能描述:LED照明驅動器 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: 安裝風格:SMD/SMT 封裝 / 箱體:SO-16N |
| LM27951SDX/NOPB | 功能描述:LED照明驅動器 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: 安裝風格:SMD/SMT 封裝 / 箱體:SO-16N |
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