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參數(shù)資料
| 型號(hào)： | L6668 |
| 廠商： | 意法半導(dǎo)體 |
| 英文描述： | SMART PRIMARY CONTROLLER |
| 中文描述： | 智能主控制器 |
| 文件頁(yè)數(shù)： | 12/23頁(yè) |
| 文件大?。?/td> | 671K |
| 代理商： | L6668 |
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L6668
12/23
4
The L6668 is a versatile current-mode PWM controller specific for offline fixed-frequency, peak-current-
mode-controlled flyback converters.
The device is able to operate in different modes (fig. 34), depending on the converter's load conditions:
1) Fixed frequency at heavy load. In this region the IC operates exactly like a standard current mode control
chip: a relaxation oscillator, externally programmable with a capacitor and a resistor, generates a sawtooth
and releases a clock pulse during the falling edge of the sawtooth; the power switch is turned on by the clock
pulses and is turned off by the control loop.
2) Frequency-foldback mode at medium and light load. As the load is reduced the oscillator frequency is re-
duced as well by slowing down the charge of the timing capacitor proportionally to the load itself.
3) Burst-mode control with no or very light load. When the load is extremely light or disconnected, the converter
will enter a controlled on/off operation with constant peak current. A load decrease will be then translated
into a frequency reduction, which can go down even to few hundred hertz, thus minimizing all frequency-
related losses and making it easier to comply with energy saving regulations. Being the peak current very
low, no issue of audible noise arises.
Application Information
Figure 34. Multi-mode operation of the L6668
4.1 High-voltage start-up generator
Figure 35 shows the internal schematic of the high-voltage start-up generator (HV generator). It is made
up of a high-voltage N-channel FET, whose gate is biased by a 15 M
resistor, with a temperature-com-
pensated current generator connected to its source.
Figure 35. High-voltage start-up generator: internal schematic
The HV generator is physically located on a separate chip, made with BCD off-line technology able to with-
stand 700V, controlled by a low-voltage chip, where all of the control functions reside.
0
0
f
sw
P
in
Fixed-frequency mode
Frequency foldback mode
Pinmax
L6668
15 M
GND
HV
Vcc
5
3
1
I
charge
Vcc_OK
I
HV
CONTROL
HV_EN
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| L6712A | TWO-PHASE INTERLEAVED DC/DC CONTROLLER |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| L6668_06 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:SMART PRIMARY CONTROLLER |
| L6668B2 | 功能描述:電流型 PWM 控制器 POWER SUPPLY RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| L6668TR | 功能描述:電流型 PWM 控制器 SMART CONTROLLER RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| L667 | 制造商:BURNDY 功能描述:L-DIE |
| L-667 | 制造商:RHOMBUS-IND 制造商全稱:Rhombus Industries Inc. 功能描述:Common Mode Inductor For DC/DC Power supply |
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