- 您現(xiàn)在的位置：買(mǎi)賣(mài)IC網(wǎng) > PDF目錄44553 > LM3544MX-H/NOPB (NATIONAL SEMICONDUCTOR CORP) 2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO16 PDF資料下載
參數(shù)資料
| 型號(hào)： | LM3544MX-H/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 電源管理 |
| 英文描述： | 2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO16 |
| 封裝： | SOIC-16 |
| 文件頁(yè)數(shù)： | 3/13頁(yè) |
| 文件大?。?/td> | 785K |
| 代理商： | LM3544MX-H/NOPB |
第1頁(yè)第2頁(yè)當(dāng)前第3頁(yè)第4頁(yè)第5頁(yè)第6頁(yè)第7頁(yè)第8頁(yè)第9頁(yè)第10頁(yè)第11頁(yè)第12頁(yè)第13頁(yè)
Typical Applications
ROOT AND SELF-POWERED USB HUBS
The LM3544 has been designed primarily for use in root and
self-powered USB hubs. In this application, the switches of
the LM3544 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 LM3544. A schematic of a circuit
that uses the LM3544 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
LM3544 power switches will ensure that the hub power
outputs meet the USB voltage drop specification even with a
500mA load, the maximum allowed in the USB standard.
BUS-POWERED USB HUBS
The LM3544 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-
powered hubs. With bus-powered hubs, however, there is no
internal power supply to drive the input pins of the LM3544.
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 LM3544 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 deliv-
ered to the device were to exceed the 2.0A over-current
threshold (typ.) of the LM3544, switches in violation would
open to protect the device from damage.
In addition to in-rush current limiting, the LM3544 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 con-
nection is detected and enumerated, and if the upstream
device is capable of supplying the required power, the high-
power function may draw up to five unit loads (500mA). With
the proper control signals, the LM3544 can be used to
achieve this staged power connection. When the function is
connected to the bus, one or more of the LM3544 switches
can be closed to connect bus power only to circuitry needed
during the connection and enumeration process. If the func-
tion is to be powered fully, remaining switches on the
LM3544 can be closed to connect all blocks of the function to
the power bus. Figure 7 illustrates how the LM3544 can be
connected for use in bus powered functions.
WAKE-ON-USB AND REMOTE WAKEUP
APPLICATIONS
The LM3544 can be used in desktop and notebook PC
based root hubs to switch the power connection of USB
devices between the main power source, used when the
device is active, and a reduced power auxiliary supply. The
auxiliary supply, used when the device is in suspend mode,
can dramatically decrease the power consumption of a com-
puter that contains devices that spend extended periods of
time in suspend mode. This application also works especially
well with devices configured for remote wakeup capabilities
(i.e.: using a keystroke on a mouse or keyboard to awaken a
suspended PC). A schematic showing an example of how
10120831
FIGURE 7. Using the LM3544 in USB Bus-Powered Functions
LM3544
www.national.com
11
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM3578AH | 0.75 A SWITCHING REGULATOR, 100 kHz SWITCHING FREQ-MAX, MBCY8 |
| LM1578AH | 0.75 A SWITCHING REGULATOR, 100 kHz SWITCHING FREQ-MAX, MBCY8 |
| LM3620M5X-8/NOPB | BATTERY CHARGE CONTROLLER, PDSO5 |
| LM3620M5X-4/NOPB | BATTERY CHARGE CONTROLLER, PDSO5 |
| LM3622A-8.4MDC | BATTERY CHARGE CONTROLLER, UUC |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM3544MX-L | 功能描述:電源開(kāi)關(guān) IC - USB RoHS:否 制造商:Micrel 電源電壓-最小:2.7 V 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:SOIC-8 封裝:Tube |
| LM3544MX-L/NOPB | 功能描述:電源開(kāi)關(guān) IC - USB RoHS:否 制造商:Micrel 電源電壓-最小:2.7 V 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:SOIC-8 封裝:Tube |
| LM3549 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Evaluation Kit high power LED driver with up to 700mA |
| LM3549SQ/NOPB | 功能描述:LED照明驅(qū)動(dòng)器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
| LM3549SQE/NOPB | 功能描述:LED照明驅(qū)動(dòng)器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。