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參數(shù)資料
| 型號： | Si786 |
| 廠商： | Vishay Intertechnology,Inc. |
| 英文描述： | Dual-Output Power-Supply Controller(用于便攜電腦電源轉換的雙輸出步降轉換器) |
| 中文描述： | 雙輸出電源控制器（用于便攜電腦電源轉換的雙輸出步降轉換器） |
| 文件頁數(shù)： | 11/13頁 |
| 文件大?。?/td> | 497K |
| 代理商： | SI786 |
Si786
Vishay Siliconix
FaxBack 408-970-5600, request 70189
www.siliconix.com
S-60752—Rev. G, 05-Apr-99
11
The path of current then becomes the circuit made of the
Schottky diode, inductor and load, which will charge the
output capacitor. The diode has a 0.5-V forward voltage drop,
which contributes a significant amount of power loss,
decreasing efficiency. A low-side switch is placed in parallel
with the Schottky diode and is turned on just after the diode
begins to conduct. Because the r
DS(ON)
of the MOSFET is
low, the I*R voltage drop will not be as large as the diode,
which increases efficiency. The low-side rectifier is shut off
when the inductor current drops to zero.
Shoot-through current is the result when both the high-side
and rectifying MOSFETs are turned on at the same time.
Break-before-make timing internal to the Si786 manages this
potential problem. During the time when neither MOSFET is
on, the Schottky is conducting, so that the body diode in the
low-side MOSFET is not forced to conduct.
Synchronous rectification is always active when the Si786 is
powered-up, regardless of the operational mode.
Gate-Driver Boost
The high-side n-channel drive is supplied by a flying-capacitor
boost circuit (see Figure 4). The capacitor takes a charge
from V
L
and then is connected from gate to source of the
high-side MOSFET to provide gate enhancement. At power-
up, the low-side MOSFET pulls LX_ down to GND and
charges the BST_ capacitor connected to 5 V. During the
second half of the oscillator cycle, the controller drives the
gate of the high-side MOSFET by internally connecting node
BST_ to DH_. This supplies a voltage 5 V higher than the
battery voltage to the gate of the high-side MOSFET.
Oscillations on the gates of the high-side MOSFET in
discontinuous mode are a natural occurrence caused by the
LC network formed by the inductor and stray capacitance at
the LX_ pins. The negative side of the BST_ capacitor is
connected to the LX_ node, so ringing at the inductor is
translated through to the gate drive.
FIGURE 4.
Boost Supply for Gate Drivers
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相關代理商/技術參數(shù) |
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|---|---|
| SI7860ADP | 制造商:VISHAY 制造商全稱:Vishay Siliconix 功能描述:N-Channel Reduced, Fast Switching MOSFET |
| SI7860ADP-T1-E3 | 功能描述:MOSFET 30V 16A 4.8W 9.5mohm @ 10V RoHS:否 制造商:STMicroelectronics 晶體管極性:N-Channel 汲極/源極擊穿電壓:650 V 閘/源擊穿電壓:25 V 漏極連續(xù)電流:130 A 電阻汲極/源極 RDS（導通）:0.014 Ohms 配置:Single 最大工作溫度: 安裝風格:Through Hole 封裝 / 箱體:Max247 封裝:Tube |
| SI7860ADP-T1-GE3 | 功能描述:MOSFET 30V 16A 4.8W 9.5mohm @ 10V RoHS:否 制造商:STMicroelectronics 晶體管極性:N-Channel 汲極/源極擊穿電壓:650 V 閘/源擊穿電壓:25 V 漏極連續(xù)電流:130 A 電阻汲極/源極 RDS（導通）:0.014 Ohms 配置:Single 最大工作溫度: 安裝風格:Through Hole 封裝 / 箱體:Max247 封裝:Tube |
| SI7860DP | 制造商:VISHAY 制造商全稱:Vishay Siliconix 功能描述:N-Channel Reduced Qg, Fast Switching MOSFET |
| SI7860DP-E3 | 功能描述:MOSFET N-Ch 30V 18A RoHS:否 制造商:STMicroelectronics 晶體管極性:N-Channel 汲極/源極擊穿電壓:650 V 閘/源擊穿電壓:25 V 漏極連續(xù)電流:130 A 電阻汲極/源極 RDS（導通）:0.014 Ohms 配置:Single 最大工作溫度: 安裝風格:Through Hole 封裝 / 箱體:Max247 封裝:Tube |
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