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參數(shù)資料
| 型號： | LP3954 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Advanced Lighting Management Unit |
| 中文描述： | 高級照明管理單位 |
| 文件頁數(shù)： | 8/56頁 |
| 文件大?。?/td> | 5801K |
| 代理商： | LP3954 |
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Magnetic Boost DC/DC Converter
The LP3954 Boost DC/DC Converter generates a 4.0 – 5.3V
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 op-
tions for switching frequency, 1MHz, 1.67MHz and 2MHz
(default), when timing resistor RT is 82kohm. Timing resistor
defines the internal oscillator frequency and thus directly af-
fects boost frequency and all circuit's internally generated
timing (RGB, Flash, WLED fading).
The LP3954 Boost Converter uses pulse-skipping elimination
to stabilize the noise spectrum. Even with light load or no load
a minimum length current pulse is fed to the inductor. An ac-
tive 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 skip-
ping. Reducing the switching frequency will also reduce the
required voltage difference.
Active load can be disabled with the en_autoload bit. Dis-
abling will increase the efficiency at light loads, but the down-
side is that pulse skipping will occur. The Boost Converter
should be stopped when there is no load to minimise the cur-
rent 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.
Over current protection, limits the maximum inductor
current
2.
—
Voltage over switching NMOS is monitored; too high
voltages turn the switch off.
Feedback break protection. Prevents uncontrolled
operation if FB pin gets disconnected.
Duty cycle limiting, done with digital control.
3.
4.
20132208
Boost Converter Topology
www.national.com
8
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相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LP3954RL | Advanced Lighting Management Unit |
| LP3954RLX | Advanced Lighting Management Unit |
| LP3954TL | Advanced Lighting Management Unit |
| LP3954TLX | Advanced Lighting Management Unit |
| LP3958 | Lighting Management Unit with High Voltage Boost Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LP39542 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Advanced Lighting Management Unit |
| LP39542RL | 制造商:Texas Instruments 功能描述:IC, LIGHTING MGNT UNIT, SMD |
| LP39542RL/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 |
| LP39542RLX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Advanced Lighting Management Unit |
| LP39542RLX/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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