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參數(shù)資料
| 型號： | LM2674-5.0MDC |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1.25 A SWITCHING REGULATOR, 275 kHz SWITCHING FREQ-MAX, UUC |
| 封裝： | DIE |
| 文件頁數(shù)： | 4/31頁 |
| 文件大小： | 596K |
| 代理商： | LM2674-5.0MDC |
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LM2674 Series Buck Regulator Design Procedure (Fixed Output) (Continued)
PROCEDURE (Fixed Output Voltage Version)
EXAMPLE (Fixed Output Voltage Version)
A low ESR aluminum or tantalum bypass capacitor is needed
between the input pin and ground to prevent large voltage
transients from appearing at the input. This capacitor should be
located close to the IC using short leads. In addition, the RMS
current rating of the input capacitor should be selected to be at
least 12 the DC load current. The capacitor manufacturer data
sheet must be checked to assure that this current rating is not
exceeded. The curves shown in
Figure 14 show typical RMS
current ratings for several different aluminum electrolytic
capacitor values. A parallel connection of two or more
capacitors may be required to increase the total minimum RMS
current rating to suit the application requirements.
For an aluminum electrolytic capacitor, the voltage rating should
be at least 1.25 times the maximum input voltage. Caution must
be exercised if solid tantalum capacitors are used. The tantalum
capacitor voltage rating should be twice the maximum input
voltage. The tables in
Figure 15 show the recommended
application voltage for AVX TPS and Sprague 594D tantalum
capacitors. It is also recommended that they be surge current
tested by the manufacturer. The TPS series available from AVX,
and the 593D and 594D series from Sprague are all surge
current tested. Another approach to minimize the surge current
stresses on the input capacitor is to add a small inductor in
series with the input supply line.
Use caution when using ceramic capacitors for input bypassing,
because it may cause severe ringing at the V
IN pin.
The important parameters for the input capacitor are the input
voltage rating and the RMS current rating. With a maximum
input voltage of 12V, an aluminum electrolytic capacitor with a
voltage rating greater than 15V (1.25 x V
IN) would be needed.
The next higher capacitor voltage rating is 16V.
The RMS current rating requirement for the input capacitor in a
buck regulator is approximately 12 the DC load current. In this
example, with a 500mA load, a capacitor with an RMS current
rating of at least 250 mA is needed. The curves shown in
14 can be used to select an appropriate input capacitor. From
the curves, locate the 16V line and note which capacitor values
have RMS current ratings greater than 250 mA.
For a through hole design, a 100 F/16V electrolytic capacitor
(Panasonic HFQ series, Nichicon PL, Sanyo MV-GX series or
equivalent) would be adequate. Other types or other
manufacturers’ capacitors can be used provided the RMS ripple
current ratings are adequate. Additionally, for a complete
surface mount design, electrolytic capacitors such as the Sanyo
CV-C or CV-BS and the Nichicon WF or UR and the NIC
Components NACZ series could be considered.
For surface mount designs, solid tantalum capacitors can be
used, but caution must be exercised with regard to the capacitor
surge current rating and voltage rating. In this example,
checking Figure 15, and the Sprague 594D series datasheet, a
Sprague 594D 15 F, 25V capacitor is adequate.
5. Boost Capacitor (C
B)
5. Boost Capacitor (C
B)
This capacitor develops the necessary voltage to turn the switch
gate on fully. All applications should use a 0.01 F, 50V ceramic
capacitor.
For this application, and all applications, use a 0.01 F, 50V
ceramic capacitor.
LM2674
www.national.com
12
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM2674LD-12 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:SIMPLE SWITCHER Power Converter High Efficiency 500 mA Step-Down Voltage Regulator |
| LM2674LD-12/NOPB | 功能描述:IC REG BUCK 12V 0.5A 16LLP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:SIMPLE SWITCHER® 產(chǎn)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 |
| LM2674LD-3.3 | 功能描述:直流/直流開關轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率: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 |
| LM2674LD-3.3/NOPB | 功能描述:直流/直流開關轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率: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 |
| LM2674LD-5.0 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:SIMPLE SWITCHER Power Converter High Efficiency 500 mA Step-Down Voltage Regulator |
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