4 2006 Semtech Corp.
www.semtech.com
PROTECTION PRODUCTS
STF203-15 THRU STF203-33
Device Connection
The STF203 is designed to provide termination, EMI
filtering and ESD protection for one USB port. The
device is connected as follows:
1.1.
1.1.
1. Full-Speed Devices: For full-speed devices the
pull-up resistor is connected to the D+ line. Route
the D+ line from the connector to pin 1 of the
STF203. Pin 6 is connected to the D+ line of the
IC. Route the D- line from the connector to pin 3.
Pin 4 is connected to the D- line of the IC. Pin 5 is
connected to the voltage supply line (V
BUS
). Pin 2 is
connected to ground. Note that the input and
output connections may be reversed if necessary
(See Figure 3).
2.2.
2.2.
2. Low-Speed Devices
::
::
: For low speed devices the
pull-up resistor is connected to the D- line. Route
the D- line from the connector to pin 1 of the
STF203. Pin 6 is connected to the D- line of the IC.
Route the D+ line from the connector to pin 3. Pin
4 is connected to the D+ line of the IC. Pin 5 is
connected to the voltage supply line (V
BUS
). Pin 2 is
connected to ground. Note that the input and
output connections may be reversed if necessary
(See Figure 4).
USB Port Design Considerations
The Universal Serial Bus (USB) specification requires
termination and filtering components for proper opera-
tion. In addition, an open USB socket is vulnerable to
hazardous ESD discharges in excess of 15kV. These
discharges can occur on the data lines or the voltage
bus. The STF203 is an easily implemented solution
that is designed to meet the termination and EMI filter
requirements of the USB specification revision 1.1. It
also provides ESD protection to IEC 61000-4-2,
level 4.
USB line termination is achieved with series resistors
on both the D+ and D- lines. These resistors preserve
signal integrity by matching the cable impedance to
that of the differential driver. A 1.5kΩ pull-up resistor
is used to identify an upstream port on either the D+
(full speed devices) or the D- (low speed devices) data
line. Capacitors are used for EMI suppression. TVS
diodes provide ESD protection of both (D+ and D-)
data lines and the voltage bus (V
BUS
). The STF203
integrates all of these components in a small SC-70
package. This integrated solution simplifies design and
requires minimal board space.
Figure 1 - Preferred Connection Diagram
(Full Speed Devices)
Applications Information
Figure 2 - Preferred Connection Diagram
(Low Speed Devices)
1
2
34
5
6
STF203
From Connector
1
2
34
5
6
STF203
From Connector
Figure 4 - Alternate Connection Diagram
(Low Speed Devices)
Figure 3 - Alternate Connection Diagram
(Full Speed Devices)
1
2
34
5
6
STF203
From Connector
1
2
34
5
6
STF203
From Connector
