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参数资料
| 型号： | LM25085MMY |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING CONTROLLER, PDSO8 |
| 封装： | MSOP-8 |
| 文件页数： | 11/24页 |
| 文件大小： | 465K |
| 代理商： | LM25085MMY |
Alternate Output Ripple
Configurations
The minimum ripple configuration, using C1, C2 and R3, used
in the example circuit figure 4, results in a low ripple amplitude
at V
OUT determined mainly by the characteristics of the output
capacitor and the ripple current in L1. This configuration al-
lows multiple ceramic capacitors to be used for V
OUT if the
output voltage is provided to several places on the PC board.
However, if a slightly higher level of ripple at V
OUT is accept-
able in the application, and distributed capacitance is not
used, the ripple required for the FB comparator pin can be
generated with fewer external components using the circuits
shown below.
a) Reduced ripple configuration:
In Figure 9, R3, C1 and
C2 are removed (compared to Figure 4). A low value resistor
(R4) is added in series with C
OUT, and a capacitor (Cff) is
added across R
FB2. Ripple is generated at VOUT by the
inductor’s ripple current flowing through R4, and that ripple
voltage is passed to the FB pin via Cff. The ripple at V
OUT can
be set as low as 25 mVp-p since it is not attenuated by R
FB2
and R
FB1. The minimum value for R4 is calculated from:
where I
OR(min) is the minimum ripple current, which occurs at
minimum input voltage. The minimum value for Cff is deter-
mined from:
where t
ON(max) is the maximum on-time, which occurs at min-
imum VIN. The next larger standard value capacitor should
be used for Cff.
30079349
FIGURE 9. Reduced Ripple Configuration
b) Lowest cost configuration:
This configuration, shown in
Figure 10, is the same as Figure 9 except Cff is removed.
Since the ripple voltage at V
OUT is attenuated by RFB2 and
R
FB1, the minimum ripple required at VOUT is equal to:
V
RIP(min) = 25 mV x (RFB2 + RFB1)/RFB1
The minimum value for R4 is calculated from:
where I
OR(min) is the minimum ripple current, which occurs at
minimum input voltage.
19
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LM25085
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM25085MY | 制造商:NSC 制造商全称:National Semiconductor 功能描述:42V Constant On-Time PFET Buck Switching Controller |
| LM25085MY/NOPB | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| LM25085MYE | 制造商:Texas Instruments 功能描述:DC DC Cntrlr Single-OUT Buck 4.5V to 42V Input 8-Pin MSOP EP T/R 制造商:Texas Instruments 功能描述:IC, SW BUCK CONTROLLER, 42V, 8MSOIC 制造商:Texas Instruments 功能描述:IC, SW BUCK CONTROLLER, 42V, 8MSOIC; Primary Input Voltage:42V; No. of Outputs:1; Output Voltage:42V; Output Current:10A; Voltage Regulator Case Style:MSOP; No. of Pins:8; Operating Temperature Min:-40C; Operating Temperature ;RoHS Compliant: Yes |
| LM25085MYE/NOPB | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| LM25085MYEVAL | 功能描述:BOARD EVAL FOR LM25085 MSOP RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:PowerWise® 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
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