LX7203-xx
P
RODUCTION
D
ATA
S
HEET
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 4
WWW.Microsemi .COM
EMI Filter & ESD Protection for Up Stream USB
Ports
Copyright © 2002
Rev. 1.1d, 2005-05-18
TM
®
APPLICATION INFORMATION (CONTINUED)
L
OW
S
PEED
D
EVICE
(
FIGURE
3)
The USB v1.1 specification offers a 1.5 Mbps data
transfer rate known as Low-Speed which requires a 1.5 kΩ
pull-up resistor to be connected to the D- line. Slew rate
control is accomplished with C
EDGE
attached to the
transceiver before the R
S
.
Voltage Supply (Vbus) is connected to Pin 5
Ground is connected to Pin 2
D+ from the connector is routed to Pin 3 and Pin 4 to
the D+ line of the USB Transceiver
D- from the connector is routed to Pin 1 (1.5 kΩ pull-up
resistor) and Pin 6 to the D- line of the USB Transceiver
cable
Host
USB
Transceiver
GND
D+
D-
V
BUS
Peripheral
USB
Transceiver
GND
D+
D-
V
BUS
R
PU
1
6
5
43
2
V
BUS
D
IN
from connector
D
OUT
to IC
GND
D
IN
from connector
D
OUT
to IC
LX7203
Figure 3 – Connection for Low Speed Operation
ELECTROMAGNETIC EMISSION AND SUSCEPTABILITY
FCC Part 15 sets limits for maximum allowable EM
emission and susceptibility. There are two types of
emissions. Conducted emissions with frequency of
emission of 0.45 to 30 MHz and radiated emissions with
frequency of emission of 30 MHz to 40 GHz. All digital
computing devices including the peripheral devices must
comply. Examples of peripheral devices include terminals,
printers, external floppy disk drives and other data storage
devices, video monitors, keyboards, control cards, interface
boards, external memory expansion cards and other
input/output devices that may or may not contain digital
circuitry. LX7203 is optimized to minimize the radiated
EMI which is the primary concern in devices using USB.
Refer to the typical filter response curve for the attenuation
characteristics of LX7203 over the frequency range of
30kHz to 6GHz.
A
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