參數(shù)資料
型號(hào)： LM3743
廠商： National Semiconductor Corporation
英文描述： N-Channel FET Synchronous Buck Controller for Low Output Voltages
中文描述： N溝道FET的同步降壓控制器，用于低輸出電壓
文件頁(yè)數(shù)： 20/23頁(yè)
文件大?。?/td> 1145K
代理商： LM3743
Application Information
(Continued)
In practice, a good trade off between phase margin and
bandwidth can be obtained by selecting the closest
±
10%
capacitor values above what are suggested for C7 and C8,
the closest
±
10% capacitor value below the suggestion for
C9, and the closest
±
1% resistor values below the sugges-
tions for R4, R5. Note that if the suggested value for R5 is
less than 100
, it should be replaced by a short circuit.
Following this guideline, the compensation components will
be:
C7 = 47 pF
±
10%, C9 = 1.5 nF
±
10%
C8 = 2.2 nF
±
10%, R4 = 22.6 k
±
1%
R5 = 2.1 k
±
1%
The transfer function of the compensation block can be
derived by considering the compensation components as
impedance blocks Z
F
and Z
I
around an inverting op-amp:
As with the generic equation, G
must be modified
to take into account the limited bandwidth of the error ampli-
fier. The result is:
The total control loop transfer function H is equal to the
power stage transfer function multiplied by the error amplifier
transfer function.
H = G
PS
x H
EA
The bandwidth and phase margin can be read graphically
from Bode plots of H
EA
as shown in
Figure 11
.
The bandwidth of this example circuit is 59 kHz, with a phase
margin of 60.
EFFICIENCY CALCULATIONS
The following is a sample calculation.
A reasonable estimation of the efficiency of a switching buck
controller can be obtained by adding together the Output
Power (P
OUT
) loss and the Total Power loss (P
LOSS
):
20177429
20177450
FIGURE 11. Overall Loop Gain and Phase
L
www.national.com
20
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM3743-1000EVAL 功能描述:電源管理IC開(kāi)發(fā)工具 LM3743 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V
LM3743-300EVAL 功能描述:電源管理IC開(kāi)發(fā)工具 LM3743 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V
LM3743MM-1000 功能描述:電壓模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
LM3743MM-1000/NOPB 功能描述:電壓模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
LM3743MM-300 功能描述:電壓模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
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