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参数资料
| 型号： | LM10506TME |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PBGA34 |
| 封装： | 0.40 MM PITCH, MICRO SMD-34 |
| 文件页数： | 22/34页 |
| 文件大小： | 1020K |
| 代理商： | LM10506TME |
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21.2.3 OUTPUT AND INPUT CAPACITORS
CHARACTERISTICS
Special attention should be paid when selecting these com-
ponents. As shown in the following figure, the DC bias of these
capacitors can result in a capacitance value that falls below
the minimum value given in the recommended capacitor
specifications table. Note that the graph shows the capaci-
tance out of spec for the 0402 case size capacitor at higher
bias voltages. It is therefore recommended that the capacitor
manufacturers’ specifications for the nominal value capacitor
are consulted for all conditions, as some capacitor sizes (e.g.,
0402) may not be suitable in the actual application.
30166215
FIGURE 7. Typical Variation in Capacitance vs.
DC Bias
The ceramic capacitor’s capacitance can vary with tempera-
ture. The capacitor type X7R, which operates over a temper-
ature range of 55°C to +125°C, will only vary the capacitance
to within ±15%. The capacitor type X5R has a similar toler-
ance over a reduced temperature range of 55°C to +85°C.
Many large value ceramic capacitors, larger than 1F are
manufactured with Z5U or Y5V temperature characteristics.
Their capacitance can drop by more than 50% as the tem-
perature varies from 25°C to 85°C. Therefore X7R is recom-
mended over Z5U and Y5V in applications where the ambient
temperature will change significantly above or below 25°C.
Tantalum capacitors are less desirable than ceramic for use
as output capacitors because they are more expensive when
comparing equivalent capacitance and voltage ratings in the
0.47 F to 44 F range. Another important consideration is
that tantalum capacitors have higher ESR values than equiv-
alent size ceramics. This means that while it may be possible
to find a tantalum capacitor with an ESR value within the sta-
ble range, it would have to be larger in capacitance (which
means bigger and more costly) than a ceramic capacitor with
the same ESR value. It should also be noted that the ESR of
a typical tantalum will increase about 2:1 as the temperature
goes from 25°C down to 40°C, so some guard band must
be allowed.
21.2.3.1 Output Capacitor Selection
The output capacitor of a switching converter absorbs the AC
ripple current from the inductor and provides the initial re-
sponse to a load transient. The ripple voltage at the output of
the converter is the product of the ripple current flowing
through the output capacitor and the impedance of the ca-
pacitor. The impedance of the capacitor can be dominated by
capacitive, resistive, or inductive elements within the capaci-
tor, depending on the frequency of the ripple current. Ceramic
capacitors have very low ESR and remain capacitive up to
high frequencies. Their inductive component can usually be
neglected at the frequency ranges at which the switcher op-
erates.
30166216
The output-filter capacitor smooths out the current flow from
the inductor to the load and helps maintain a steady output
voltage during transient load changes. It also reduces output
voltage ripple. These capacitors must be selected with suffi-
cient capacitance and low enough ESR to perform these
functions.
Note that the output voltage ripple increases with the inductor
current ripple and the Equivalent Series Resistance of the
output capacitor (ESR
COUT). Also note that the actual value
of the capacitor’s ESR
COUT is frequency and temperature de-
pendent, as specified by its manufacturer. The ESR should
be calculated at the applicable switching frequency and am-
bient temperature.
30166217
29
www.national.com
LM10506
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM10506TME/NOPB | 功能描述:直流/直流开关转换器 Triple Buck & LDO Power Mgmt Unit RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM10506TME-A | 制造商:TI 制造商全称:Texas Instruments 功能描述:Triple Buck LDO Power Management Unit |
| LM10506TME-A/NOPB | 功能描述:直流/直流开关转换器 Triple Buck & LDO Power Mgmt Unit RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM10506TMX | 制造商:TI 制造商全称:Texas Instruments 功能描述:Triple Buck LDO Power Management Unit |
| LM10506TMX/NOPB | 功能描述:PMIC 解决方案 Triple Buck & LDO Power Mgmt Unit RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
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