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| 型号： | LM2735YSDEVAL |
| 厂商： | National Semiconductor |
| 文件页数： | 11/58页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL LM2735 520KHZ 6LLP |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步升 |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 12V |
| 电流 - 输出： | 500mA |
| 输入电压： | 3 ~ 5.5 V |
| 稳压器拓扑结构： | 升压 |
| 频率 - 开关： | 520kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | LM2735 |
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Therefore:
SNVS485F – JUNE 2007 – REVISED APRIL 2013
D=
V OUT - V IN
V OUT
(2)
Power losses due to the diode (D1) forward voltage drop, the voltage drop across the internal NMOS switch, the
voltage drop across the inductor resistance (R DCR ) and switching losses must be included to calculate a more
accurate duty cycle (See Calculating Efficiency, and Junction Temperature for a detailed explanation). A more
accurate formula for calculating the conversion ratio is:
V OUT
V IN
where
=
K
D c
?
Where η equals the efficiency of the LM2735 application.
(3)
The inductor value determines the input ripple current. Lower inductor values decrease the size of the inductor,
but increase the input ripple current. An increase in the inductor value will decrease the input ripple current.
I L t ( )
V IN
L
' i L
V IN - V OUT
L
i L
= ¨ IN ?
? ? x DT S
? i L = ¨ ¨
2 ' i L
DT S
§ V ·
? L 1
§ V IN ·
? 2L 1
DT S
T S
Figure 21. Inductor Current
t
(4)
§ V IN ·
? 2 x ' i L 1
A good design practice is to design the inductor to produce 10% to 30% ripple of maximum load. From the
previous equations, the inductor value is then obtained.
L = ¨ ? x DT S
where
?
1/T S = F SW = switching frequency
(5)
One must also ensure that the minimum current limit (2.1A) is not exceeded, so the peak current in the inductor
must be calculated. The peak current (I LPK ) in the inductor is calculated by:
or
IL pk = I IN + Δ I L
IL pk = I OUT / D' + Δ I L
(6)
(7)
When selecting an inductor, make sure that it is capable of supporting the peak input current without saturating.
Inductor saturation will result in a sudden reduction in inductance and prevent the regulator from operating
correctly. Because of the speed of the internal current limit, the peak current of the inductor need only be
specified for the required maximum input current. For example, if the designed maximum input current is 1.5A
and the peak current is 1.75A, then the inductor should be specified with a saturation current limit of >1.75A.
There is no need to specify the saturation or peak current of the inductor at the 3A typical switch current limit.
Copyright ? 2007–2013, Texas Instruments Incorporated
Product Folder Links: LM2735
11
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM2735YSDEVAL | 制造商:Texas Instruments 功能描述:EVAL BOARD, LM2735Y 12V, 500mA SEPIC CON |
| LM2735YSDX | 制造商:NSC 制造商全称:National Semiconductor 功能描述:520kHz/1.6MHz - Space-Efficient Boost and SEPIC DC-DC Regulator |
| LM2735YSDX/NOPB | 功能描述:直流/直流开关调节器 RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| LM2736 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Thin SOT23 750mA Load Step-Down DC-DC Regulator |
| LM2736X | 制造商:TI 制造商全称:Texas Instruments 功能描述:LM2736 Thin SOT 750mA Load Step-Down DC-DC Regulator |
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