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参数资料
| 型号： | LM3543MX-L/NOPB |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 3-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO16 |
| 封装： | SOIC-16 |
| 文件页数： | 3/14页 |
| 文件大小： | 396K |
| 代理商： | LM3543MX-L/NOPB |
Typical Applications
ROOT AND SELF-POWERED USB HUBS
The LM3543 has been designed primarily for use in root and
self-powered USB hubs. In this application, the switches of
the LM3543 are used to connect the power source of the hub
to the power bus used by downstream devices and to protect
the hub from dangerously excessive loads and shorts to
ground. A high-power bus-powered function, low-power bus-
powered function, or a bus-powered hub can be driven
through a single port of the LM3543. A schematic of a circuit
that uses the LM3543 for power-supply switching in a typical
root or self-powered hub was shown earlier in this datasheet
in Figure 1.
Voltage drop requirements of USB power supplies require the
power outputs of the root and self-powered hubs to be no less
than 4.75V. For this reason, it is recommended that a 5V
power supply with a ±3% output voltage tolerance is used in
this application. Combining a 3% supply with a low-resistance
PCB design and the low on-resistance of the LM3543 power
switches will ensure that the hub power outputs meet the USB
voltage drop specification even with a 500mA load, the max-
imum allowed in the USB standard.
BUS-POWERED USB HUBS
The LM3543 is capable of performing the power supply
switching functions required in Bus-Powered hubs. Use here
is very similar to the configuration used in root and self-pow-
ered hubs. With bus-powered hubs, however, there is no
internal power supply to drive the input pins of the LM3543.
Instead, the input pins should be connected to the power bus
supplied by the upstream hub.
USB BUS-POWERED FUNCTIONS AND GENERAL IN-
RUSH CURRENT LIMITING APPLICATIONS
The LM3543 can be placed at the power-supply input of USB
bus-powered functions, or other similar devices, to protect
them from high in-rush currents. If the current being delivered
to the device were to exceed the 2.0A over-current threshold
(typ.) of the LM3543, switches in violation would open to pro-
tect the device from damage.
In addition to in-rush current limiting, the LM3543 can be used
in high-power bus-powered functions to keep current levels
of the function in compliance during power-up. The USB
specification requires the staged switching of power when
connecting high-power functions to the bus. When a high-
power function is initially connected to the bus, it must not
draw more than one unit supply (100mA). After a connection
is detected and enumerated, and if the upstream device is
capable of supplying the required power, the high-power func-
tion may draw up to five unit loads (500mA). With the proper
control signals, the LM3543 can be used to achieve this
staged power connection. When the function is connected to
the bus, one or more of the LM3543 switches can be closed
to connect bus power only to circuitry needed during the con-
nection and enumeration process. If the function is to be
powered fully, remaining switches on the LM3543 can be
closed to connect all blocks of the function to the power bus.
Figure 7 illustrates how the LM3543 can be connected for use
in bus powered functions.
10125831
FIGURE 7. Using the LM3543 in USB Bus-Powered Functions
11
www.national.com
101258 Version 5 Revision 6
Print Date/Time: 2010/02/04 15:48:33
LM3543
相关PDF资料 |
PDF描述 |
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| LM3543MX-H/NOPB | 3-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO16 |
| LM3686TL-AADW | 1.375 A SWITCHING REGULATOR, 3400 kHz SWITCHING FREQ-MAX, PBGA12 |
| LM385BZX | 1-OUTPUT TWO TERM VOLTAGE REFERENCE, 1.24 V, PBCY3 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM3544 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Quad Port USB Power Distribution Switch and Over-Current Protection |
| LM3544B-H E WAF | 制造商:Texas Instruments 功能描述: |
| LM3544M-H | 制造商:Texas Instruments 功能描述:2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO16 |
| LM3544M-H/NOPB | 功能描述:IC USB QUAD PORT SWITCH 16-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 电源分配开关 系列:- 特色产品:XRP252 Switches 标准包装:1 系列:- 类型:高端开关 输出数:2 Rds（开）:140 毫欧 内部开关:是 电流限制:1.15A 输入电压:1.75 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN（3x3） 包装:Digi-Reel® 其它名称:1016-1691-6 |
| LM3544M-L | 功能描述:电源开关 IC - USB RoHS:否 制造商:Micrel 电源电压-最小:2.7 V 电源电压-最大:5.5 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:SOIC-8 封装:Tube |
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