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參數(shù)資料
| 型號(hào)： | LM2853 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | 3A 550 kHz Synchronous SIMPLE SWITCHER Buck Regulator |
| 中文描述： | 第3A 550千赫同步的SIMPLE SWITCHER降壓穩(wěn)壓器 |
| 文件頁(yè)數(shù)： | 9/12頁(yè) |
| 文件大?。?/td> | 620K |
| 代理商： | LM2853 |
Applications Information
(Continued)
CHOOSING AN INDUCTANCE VALUE
The current ripple present in the output filter inductor is
determined by the input voltage, output voltage, switching
frequency and inductance according to the following equa-
tion:
where
I
L
is the peak to peak current ripple, D is the duty
cycle V
OUT
/V
IN
, V
is the input voltage applied to the output
stage, V
is the output voltage of the switcher, f is the
switching frequency and L
is the inductance of the output
filter inductor. Knowing the current ripple is important for
inductor selection since the peak current through the induc-
tor is the load current plus one half the ripple current. Care
must be taken to ensure the peak inductor current does not
reach a level high enough to trip the current limit circuitry of
the LM2853. As an example, consider a 5V to 1.2V conver-
sion and a 550 kHz switching frequency. According to
Table
1
, a 4.7 μH inductor may be used. Calculating the expected
peak-to-peak ripple,
The maximum inductor current for a 3A load would therefore
be 3A plus 177 mA, 3.177A. As shown in the ripple equation,
the current ripple is inversely proportional to inductance.
OUTPUT FILTER INDUCTORS
Once the inductance value is chosen, the key parameter for
selecting the output filter inductor is its saturation current
(I
SAT
) specification. Typically I
SAT
is given by the manufac-
turer as the current at which the inductance of the coil falls to
a certain percentage of the nominal inductance. The I
SAT
of
an inductor used in an application should be greater than the
maximum expected inductor current to avoid saturation. Be-
low is a table of inductors that are suitable in LM2853
applications.
TABLE 2. Recommended Inductors
Inductance
4.7 μF
4.7 μF
4.7 μF
5.2 μF
5.6 μF
6.8 μF
6.8 μF
Part Number
DO3308P-472ML
DO3316P-472ML
MSS1260-472ML
MSS1038-522NL
MSS1260-562ML
DO3316P-682ML
MSS1260-682ML
Vendor
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
OUTPUT FILTER CAPACITORS
The recommended capacitors that may be used in the output
filter with the LM2853 are limited in value and ESR range
according to
Table 1
.
Below are some examples of capacitors that can typically be
used in an LM2853 application.
TABLE 3. Recommended Capacitors
Capacitance (μF)
100
100
100
100
100
120
150
150
150
150
150
150
220
220
220
220
Part Number
594D107X_010C2T
593D107X_010D2_E3
TPSC107M006#0075
NOSD107M006#0080
NOSC107M004#0070
594D127X_6R3C2T
594D157X_010C2T
595D157X_010D2T
591D157X_6R3C2_20H
TPSD157M006#0050
TPSC157M004#0070
NOSD157M006#0070
594D227X_6R3D2T
591D227X_6R3D2_20H
591D227X_010D2_20H
593D227X_6R3D2_E3
Chemistry
Tantalum
Tantalum
Tantalum
Niobium Oxide
Niobium Oxide
Tantalum
Tantalum
Tantalum
Tantalum
Tantalum
Tantalum
Niobium Oxide
Tantalum
Tantalum
Tantalum
Tantalum
Vendor
Vishay-Sprague
Vishay-Sprague
AVX
AVX
AVX
Vishay-Sprague
Vishay-Sprague
Vishay-Sprague
Vishay-Sprague
AVX
AVX
AVX
Vishay-Sprague
Vishay-Sprague
Vishay-Sprague
Vishay-Sprague
L
www.national.com
9
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2853-1.2EVAL | 功能描述:電源管理IC開(kāi)發(fā)工具 LM2853 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類(lèi)型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LM2853-1.2EVAL | 制造商:Texas Instruments 功能描述:EVAL BOARD, LM2853 1.2V, 3A SYNC STEP-DO |
| LM2853-1.8EVAL | 功能描述:BOARD EVAL LM2853-1.8 RoHS:否 類(lèi)別:編程器，開(kāi)發(fā)系統(tǒng) >> 評(píng)估板 - DC/DC 與 AC/DC（離線）SMPS 系列:PowerWise®, SIMPLE SWITCHER® 標(biāo)準(zhǔn)包裝:1 系列:- 主要目的:DC/DC，步降 輸出及類(lèi)型:1，非隔離 功率 - 輸出:- 輸出電壓:3.3V 電流 - 輸出:3A 輸入電壓:4.5 V ~ 28 V 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):降壓 頻率 - 開(kāi)關(guān):250kHz 板類(lèi)型:完全填充 已供物品:板 已用 IC / 零件:L7981 其它名稱:497-12113STEVAL-ISA094V1-ND |
| LM2853-1.8EVAL/NOPB | 功能描述:電源管理IC開(kāi)發(fā)工具 LM2853 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類(lèi)型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LM2853-3.3EVAL | 功能描述:電源管理IC開(kāi)發(fā)工具 LM2853 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類(lèi)型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
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