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參數(shù)資料
| 型號： | LM3211 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Step-up PWM DC/DC Converter Integrated with 4 Buffers |
| 中文描述： | 升壓PWM直流/直流轉換器集成有4緩沖器 |
| 文件頁數(shù)： | 14/21頁 |
| 文件大?。?/td> | 821K |
| 代理商： | LM3211 |
Operation
(Continued)
V
OUT
= 8V, V
IN
= 2.5V, R
L
= 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, 11μA, 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 10μH inductor is recommended for most 600 kHz applica-
tions, while a 4.7μH 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 C
C
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
that will optimize the performance of the LM3211
circuit in terms of its transient response. The series combi-
nation of R
and C
introduces a pole-zero pair according to
the following equations:
where R
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
can be up to 200k
if C
is used, see
High
Output Capacitor ESR Compensation
) and 680pF
≤
C
C
≤
20062205
FIGURE 2. (a) Inductor current. (b) Diode current.
L
www.national.com
14
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM3211MT-ADJ | 制造商:Texas Instruments 功能描述:CONVERTER DC-DC BOOST SMD 3211 |
| LM3211MT-ADJ/NOPB | 功能描述:IC REG BOOST 8V 1.4A 20-TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:1 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3.3V 輸入電壓:4.5 V ~ 24 V PWM 型:- 頻率 - 開關:- 電流 - 輸出:125mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 包裝:Digi-Reel® 供應商設備封裝:SOT-6 其它名稱:MAX1836EUT33#TG16DKR |
| 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 |
| 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 |
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