參數(shù)資料
型號(hào)： LP39542TL
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 顯示驅(qū)動(dòng)器
英文描述： Advanced Lighting Management Unit
中文描述： LED DISPLAY DRIVER, PBGA36
封裝： 3 X 3 MM, 0.60 MM HEIGHT, 0.50 MM PITCH, MICRO, SMD-36
文件頁(yè)數(shù)： 8/58頁(yè)
文件大小： 2547K
代理商： LP39542TL
Magnetic Boost DC/DC Converter
The LP39542 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, 1 MHz, 1.67 MHz and 2 MHz
(default), when timing resistor RT is 82 k
Ω
. 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 LP39542 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. 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
—
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.
2.
3.
4.
30008508
Boost Converter Topology
www.national.com
8
L
相關(guān)PDF資料
PDF描述
LP39542TLX Advanced Lighting Management Unit
LP3954 Advanced Lighting Management Unit
LP3954RL Advanced Lighting Management Unit
LP3954RLX Advanced Lighting Management Unit
LP3954TL Advanced Lighting Management Unit
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LP39542TL/NOPB 功能描述:LED照明驅(qū)動(dòng)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
LP39542TLX 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Advanced Lighting Management Unit
LP39542TLX/NOPB 功能描述:LED照明驅(qū)動(dòng)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
LP3954RL 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Advanced Lighting Management Unit
LP3954RL/NOPB 功能描述:LED照明驅(qū)動(dòng)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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