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参数资料
| 型号： | NUF2221W1T2G |
| 厂商： | ON SEMICONDUCTOR |
| 元件分类： | 通用总线功能 |
| 英文描述： | USB Upstream Terminator with ESD Protection |
| 中文描述： | 2-LINE 1500 ohm OTHER TERMINATOR, PDSO6 |
| 封装： | LEAD FREE, SC-88, SC70, SOT-363, 6 PIN |
| 文件页数： | 3/6页 |
| 文件大小： | 68K |
| 代理商： | NUF2221W1T2G |
NUF2221W1T2
http://onsemi.com
3
APPLICATIONS BACKGROUND
What is USB
The USB is not a serial port, it is a serial bus, a fact that
enables a single port on the computer to be a link for a myriad
of devices, (up to 127 devices in a USB system). We can
easily chain one device to another and use one port as a
connecting point of many devices by using a hub. All these
enable us to look at the USB system as a small network of
devices.
The Universal Serial Bus (USB) makes connecting
devices to your computer faster, easier and virtually
limitless. HighSpeed USB devices are capable of
communicating at speeds up to 12 megabyteswithout
shutting down and without having to open your computer.
Typical USB System
Computer PC
CPU
KeyBoard
Mouse
Monitor
Telephone
Plotter
HUB
Scanner
Printer
Figure 4. Typical USB System
Typically the USB system consists of one host, hubs and
devices.
The Host
The host in the USB system, is responsible to the whole
complexity of the protocol (simplifies the designing of USB
devices). The host controls the media access, therefore, no
one can access the bus unless it got an approval required
from the host.
The Hub
The hub provides an interconnect point, which enables
many devices to connect to a single USB port. The logical
topology of the USB is a star structure, all the devices are
connected (logically) directly to the host. It is totally
transparent to the device what is its’ hub tier (the number of
hubs the data has to flow through). The hub is connected to
the USB host in the upstream direction (data flows ”up” to
the host) and is connected to the USB device in the
downstream direction (data flows ”down” from the host to
the device). The hubs’ main functionality is the
responsibility of detecting an attachment and detachment of
devices, handling the power management for devices that
are buspowered (get power from the bus), and
responsibility for bus error detection and recovery. Another
important role of the hub is to manage both full and low
speed devices. When a device is attached to the system the
hub detects the speed, which the device operates in, and
through the whole communication on the bus prevents from
full speed traffic to reach low seed device and vice versa
– prevent from low speed traffic to reach full speed device.
The Device
The Device is defined as everything in the USB system,
which is not a host (including hubs). A device provides one
or more USB functions. Most of the devices provide only
one function but there may be some, which provides more
than one and called compound devices. We refer to two
kinds of devices self powered or bus powered devices. A
device that gets its power from the bus is called bus powered
and on the other hand a device which supplies its own power
is called self powered. There are two kinds of devices for
USB 1.1:
Fullspeed devices operates in 12 Mb/s
Lowspeed devices that work in 1.5 Mb/s.
NUF2221W1T2 Device Information
The Universal Serial Bus (USB) specification revision 1.1
requires the USB drivers to have certain impedance
characteristics. The series resistance plus the USB driver
output resistance must be close to the USB cable’s
impedance of 45
unbalanced (90
transmission line reflections. In addition USB 1.1 also
requires upstream ports to be terminated with a pullup
resistor (usually 1.5 K ) from D+ or D lines to V
CC
=3.3 V
(V
CC
is usually taken from V
BUS
by using a 5 V 3.3 V
regulator). In case of EMI, the radiated and conducted EMI
should be kept within the required levels as specified by the
FCC regulations. Actual FCC regulations requires that class
B computing devices meet the specifications of maximum
levels for both radiated and conducted EMI (Radiated EMI
covers the frequency range from 30 MHz to 1 GHz and
Conducted EMI covers the 450 kHz to 30MHz range).
The NUF2221W1T2 device from On Semiconductor
provides series termination, EMI filtering and ESD
protection for the two data lines (D+, D) as well as for the
VBUS. The ESD device’s ratings comply with
IEC6100042 (Level 4), HBM class 3B and MM class C.
All these futures are offered in an integrated solution placed
balance) to minimize
相关PDF资料 |
PDF描述 |
|---|---|
| NUF2221W1T2 | USB Upstream Terminator with ESD Protection |
| NUF2222FC | 2 Line USB 1.1 Upstream EMI Filter |
| NUF2222FCT1G | 2 Line USB 1.1 Upstream EMI Filter |
| NUF2230XV6 | 2 Line EMI Filter with ESD Protection |
| NUF2230XV6T1 | 2 Line EMI Filter with ESD Protection |
相关代理商/技术参数 |
参数描述 |
|---|---|
| NUF2221W1T2G | 制造商:ON Semiconductor 功能描述:RC N/W FILTER 22OHM/42PF SC-88 |
| NUF2221W1T2-REL-REPORT | 制造商:未知厂家 制造商全称:未知厂家 功能描述:NUF2221W1T2 Reliability Report |
| NUF2222FC | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:2 Line USB 1.1 Upstream EMI Filter |
| NUF2222FCT1G | 功能描述:电磁干扰滤波器 2 Line USB 1.1 Upstream EMI Filter RoHS:否 制造商:STMicroelectronics 电容:12 pF 电路类型: 最大直流电流: 最大直流电阻: 电压额定值:6 V 容差: 端接类型:SMD/SMT 工作温度范围:- 30 C to + 85 C 系列:EMIF03 |
| NUF2230XV6 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:2 Line EMI Filter with ESD Protection |
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