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參數(shù)資料
| 型號： | LM3211MT-ADJ/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING REGULATOR, 1500 kHz SWITCHING FREQ-MAX, PDSO20 |
| 封裝： | TSSOP-20 |
| 文件頁數(shù)： | 6/21頁 |
| 文件大?。?/td> | 821K |
| 代理商： | LM3211MT-ADJ/NOPB |
Operation (Continued)
V
OUT =8V, VIN = 2.5V, RL =27
,C
SS = 330nF, T = 4ms/div,
F = 1.25MHz.
Trace:
1) SHDN, 1V/div, DC Coupled
2) I
L, 0.5A/div, DC Coupled
3) V
OUT, 5V/div, DC Coupled
20062280
T
A = 20C
20062281
T
A = 27C
20062282
T
A = 85C
When programming the softstart time externally, simply use
the equation given in the Soft-Start Capacitor section above.
This equation uses the typical room temperature value of the
soft start current, 11A, to set the soft start time.
INTRODUCTION TO COMPENSATION
The LM3211 is a current mode PWM boost converter. The
signal flow of this control scheme has two feedback loops,
one that senses switch current and one that senses output
voltage.
To keep a current programmed control converter stable
above duty cycles of 50%, the inductor must meet certain
criteria. The inductor, along with input and output voltage,
will determine the slope of the current through the inductor
(see Figure 2 (a)). If the slope of the inductor current is too
great, the circuit will be unstable above duty cycles of 50%.
A 10H inductor is recommended for most 600 kHz applica-
tions, while a 4.7H inductor may be used for most 1.25 MHz
applications. If the duty cycle is approaching the maximum of
85%, it may be necessary to increase the inductance by as
much as 2X. See Inductor and Diode Selection for more
detailed inductor sizing.
The LM3211 provides a compensation pin (V
C) to customize
the voltage loop feedback. It is recommended that a series
combination of R
C and CC be used for the compensation
network, as shown in the typical application circuit. For any
given application, there exists a unique combination of R
C
and C
C that will optimize the performance of the LM3211
circuit in terms of its transient response. The series combi-
nation of R
C and CC introduces a pole-zero pair according to
the following equations:
where R
O is the output impedance of the error amplifier,
approximately 1M
. For most applications, performance can
be optimized by choosing values within the range 5k
≤ R
C
≤ 60k (R
C can be up to 200k
if C
C2 is used, see High
Output Capacitor ESR Compensation) and 680pF
≤ C
C
≤
20062205
FIGURE 2. (a) Inductor current. (b) Diode current.
LM321
1
www.national.com
14
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM3211MTX-ADJ | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Step-up PWM DC/DC Converter Integrated with 4 Buffers |
| LM3211MTX-ADJ/NOPB | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)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 |
| LM3212 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:LM3212 PRODUCT BRIEF Step-Down DC-DC Converter with Analog Bypass Mode for RF Power Amplifiers |
| LM3212TL/NOPB | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM3212TLX/NOPB | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
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