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參數資料
| 型號： | LM2698 |
| 文件頁數： | 14/17頁 |
| 文件大小： | 503K |
| 代理商： | LM2698 |
Application Information
(Continued)
3.3V SEPIC
The LM2698 can be used to implement a SEPIC technology.
The advantages of the SEPIC topology are that it can step
up or step down an input voltage, and it has low input current
ripple.
The conversion ratio for the SEPIC is :
where
D’ = 1D
Solving for D yeilds:
To avoid subharmonic oscillations, it is recommended that
inductors L1 and L2 be the same inductance. Currents con-
ducted by the inductors are:
I
1
= I
OUT
(V
OUT
/V
IN
)
i
1
= V
IN
D/(2
*
L1
*
fs)
I
2
= I
OUT
i
1
= V
IN
D/(2
*
L2
*
fs)
The switch sees a maximum current of I
+ I
+
i
+
i
2
. If
L1 = L2 = L, the maximum switch current is given by:
I
OUT
(1 + V
OUT
/V
IN
) + V
IN
D/(L
*
fs)
The maximum load current is limited by this relationship to
the switch current.
The polarity of C
will change between each cycle, so a
ceramic capacitor should be used here. A high quality, low
ESR capacitor will directly improve efficiency because all the
load current passes through C
SEPIC
.
C
should be chosen using the same relationship as in the
boost converter (see the C
section). C
IN
must be able to
provide the necessary RMS current.
20012631
FIGURE 7. 3.3V SEPIC Converter
L
www.national.com
14
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相關代理商/技術參數 |
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| LM2698EVAL | 功能描述:電源管理IC開發(fā)工具 EVAL BOARDFOR LM2698 RoHS:否 制造商:Maxim Integrated 產品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LM2698MM-ADJ | 功能描述:直流/直流開關轉換器 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 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM2698MM-ADJ/NOPB | 功能描述:直流/直流開關轉換器 1.35A BOOST REG 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 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM2698MM-ADJ/NOPB | 制造商:Texas Instruments 功能描述:DC/DC Converter (DC-DC) / Switching Regu |
| LM2698MMX-ADJ | 功能描述:直流/直流開關轉換器 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 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
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