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參數(shù)資料
| 型號(hào)： | LM2746MXA |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Low Voltage N-Channel MOSFET Synchronous Buck Regulator Controller |
| 中文描述： | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO14 |
| 封裝： | PLASTIC, TSSOP-14 |
| 文件頁數(shù)： | 19/24頁 |
| 文件大?。?/td> | 1087K |
| 代理商： | LM2746MXA |
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 C
and C
,
the closest
±
10% capacitor value below the suggestion for
C
, and the closest
±
1% resistor values below the sugges-
tions for R
, R
C2
. Note that if the suggested value for R
is
less than 100
, it should be replaced by a short circuit.
Following this guideline, the compensation components will
be:
C
C1
= 27pF
±
10%, C
C2
= 820pF
±
10%
C
C3
= 2.7nF
±
10%, R
C1
= 39.2k
±
1%
R
C2
= 2.55k
±
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
are shown in
Figure 15
.
The bandwidth of this example circuit is 59kHz, 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 (P
TOTAL
) loss:
The Output Power (P
OUT
) for theTypical Application Circuit
design is (1.2V x 4A) = 4.8W. The Total Power (P
TOTAL
), with
an efficiency calculation to complement the design, is shown
below.
The majority of the power losses are due to low and high
side of MOSFET’s losses. The losses in any MOSFET are
group of switching (P
SW
) and conduction losses(P
CND
).
P
FET
= P
SW
+ P
CND
= 61.38mW + 270.42mW
P
FET
= 331.8mW
FET Switching Loss (P
SW
)
P
SW
= P
SW(ON)
+ P
SW(OFF)
20147785
20147786
FIGURE 15. Overall Loop Gain and Phase
L
www.national.com
19
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2746MXA/NOPB | 功能描述:IC REG CTRLR BUCK PWM VM 14TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤 包裝:帶卷 (TR) |
| LM2746MXAX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Low Voltage N-Channel MOSFET Synchronous Buck Regulator Controller |
| LM2746MXAX/NOPB | 功能描述:IC REG CTRLR BUCK PWM VM 14TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:100% 電源電壓:8.2 V ~ 30 V 降壓:無 升壓:無 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:是 工作溫度:0°C ~ 70°C 封裝/外殼:8-DIP（0.300"，7.62mm） 包裝:管件 產(chǎn)品目錄頁面:1316 (CN2011-ZH PDF) |
| LM2747 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Synchronous Buck Controller with Pre-bias Startup, and Optional Clock Synchronization |
| LM2747-19AEVAL | 功能描述:電源管理IC開發(fā)工具 LM2747 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 |
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