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參數(shù)資料
| 型號： | LM3477 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | High Efficiency High-Side N-Channel Controller for Switching Regulator |
| 中文描述： | 高效率高側N溝道開關穩(wěn)壓器控制器 |
| 文件頁數(shù)： | 20/23頁 |
| 文件大小： | 815K |
| 代理商： | LM3477 |
Compensation
(Continued)
The strategy taken here for choosing R
c
and C
C1
is to set the
crossover frequency with R
c
, and set the compensator zero
with C
C1
. Using the selected target crossover frequency, f
C
,
set R
C
to:
f
= Crossover frequency in Hertz (20kHz - 50kHz is recom-
mended)
R
GM
= 50x10
3
GM = 1000x10
6
A/V
The compensator zero, f
, is set with C
. When fast tran-
sient responses are desired, f
should be placed as high as
possible, however it should not be higher than the selected
crossover frequency f
. The guideline proposed here is to
choose C
such that f
falls somewhere between the
power pole f
P1
and
1
2
decade before the selected crossover
frequency fc:
In this compensation scheme, the pole created by C
is
used to cancel out the zero created by the ESR of the output
capacitor. In other schemes such as the methods discussed
in the
SAMPLING POLE QUALITY FACTOR
subsection, the
ESR zero is used. For the typical case, use C
C2
if:
Plotting the Open Loop Response
The open loop response is expressed as:
T = A
DC
x A
CM
x H x F
p
(s) x F
c
(s)
Where A
DC
and H are given above and
A
CM
= GM x R
GM
One can plot the magnitude and phase of the open loop
response to analyze the frequency response.
Example: Compensation Design
4.5V
≤
V
IN
≤
5.5V
V
OUT
= 2.5V
I
OUT
= 3A (R = 0.83
)
R
SN
= 0.02
L = 3.3μH
R
SL
= 0
C
OUT
= 100μF
R
ESR
= 0.01
First, calculate the power stage parameters using V
IN(MIN)
and R
(MAX)
:
In this example, a crossover frequency of 20kHz is chosen,
so: f
= 20000. R
is now calculated using the power stage
information and the target crossover frequency f
C
:
This sets the high frequency gain of the compensator such
that a crossover frequency of f
is obtained. The capacitor
C
sets the compensator zero, f
. Set f
between the
power pole f
and the
1
2
decade before the target cross-
over frequency f
C
:
L
www.national.com
20
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PDF描述 |
|---|---|
| LM3477A | High Efficiency High-Side N-Channel Controller for Switching Regulator |
| LM3477AMM | High Efficiency High-Side N-Channel Controller for Switching Regulator |
| LM3477AMMX | High Efficiency High-Side N-Channel Controller for Switching Regulator |
| LM3477MM | High Efficiency High-Side N-Channel Controller for Switching Regulator |
| LM3477MMX | High Efficiency High-Side N-Channel Controller for Switching Regulator |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM3477A | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:High Efficiency High-Side N-Channel Controller for Switching Regulator |
| LM3477AMM | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| LM3477AMM/NOPB | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| LM3477AMMX | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| LM3477AMMX/NOPB | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
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