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參數(shù)資料
| 型號： | LP55281 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Quad RGB Driver |
| 中文描述： | 四RGB驅(qū)動器 |
| 文件頁數(shù)： | 9/28頁 |
| 文件大小： | 1313K |
| 代理商： | LP55281 |
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Magnetic Boost DC/DC Converter
The LP55281 Boost DC/DC Converter generates a 4.0 - 5.3V
supply voltage for the LEDs from single Li-Ion battery (3V...
4.5V). The output voltage is controlled with an 8-bit register
in 9 steps. The converter is a magnetic switching PWM mode
DC/DC converter with a current limit. The converter has three
options for switching frequency, 1 MHz, 1.67 MHz and 2 MHz
(default), when timing resistor RT is 82 k
. Timing resistor
defines the internal oscillator frequency and thus directly af-
fects boost frequency and all circuit's internally generated
timing (RGB, ALED).
The LP55281 Boost Converter uses pulse-skipping elimina-
tion to stabilize the noise spectrum. Even with light load or no
load a minimum length current pulse is fed to the inductor. An
active load is used to remove the excess charge from the
output capacitor at very light loads. At very light load and when
input and output voltages are very close to each other, the
pulse skipping is not completely eliminated. Output voltage
should be at least 0.5V higher than input voltage to avoid
pulse skipping. Reducing the switching frequency will also
reduce the required voltage difference.
Active load can be disabled with the EN_AUTOLOAD bit.
Disabling will increase the efficiency at light loads, but the
downside is that pulse skipping will occur. The Boost Con-
verter should be stopped when there is no load to minimise
the current consumption.
The topology of the magnetic boost converter is called CPM
control, current programmed mode, where the inductor cur-
rent is measured and controlled with the feedback. The user
can program the output voltage of the boost converter. The
output voltage control changes the resistor divider in the feed-
back loop.
The following figure shows the boost topology with the pro-
tection circuitry. Four different protection schemes are imple-
mented:
1.
Over voltage protection, limits the maximum output
voltage
—
Keeps the output below breakdown voltage.
—
Prevents boost operation if battery voltage is much
higher than desired output.
2.
Over current protection, limits the maximum inductor
current
—
Voltage over switching NMOS is monitored; too high
voltages turn the switch off.
3.
Feedback break protection. Prevents uncontrolled
operation if FB pin gets disconnected.
4.
Duty cycle limiting, done with digital control.
20201177
Boost Converter Topology
9
www.national.com
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相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LP55281RL | Quad RGB Driver |
| LP55281RLX | Quad RGB Driver |
| LP55281TL | Quad RGB Driver |
| LP55281TLX | Quad RGB Driver |
| LP5551 | PowerWise⑩ Technology Compliant Energy Management Unit |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LP55281RL | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Quad RGB Driver |
| LP55281RL/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 |
| LP55281RLEV | 功能描述:LED 照明開發(fā)工具 LP55281RLEV EVAL BOARD RoHS:否 制造商:Fairchild Semiconductor 產(chǎn)品:Evaluation Kits 用于:FL7732 核心: 電源電壓:120V 系列: 封裝: |
| LP55281RLEV/NOPB | 制造商:Texas Instruments 功能描述:QUAD RGB DRIVER - Boxed Product (Development Kits) 制造商:Texas Instruments 功能描述:BOARD EVAL FOR LP5528 RGB DRIVER 制造商:Texas Instruments 功能描述:Quad RGB Drvr fr the PowerWise Family |
| LP55281RLX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Quad RGB Driver |
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