USBUF02W6 STMicroelectronics, USBUF02W6 Datasheet - Page 3

• Manufacturer Part Number: USBUF02W6
• Description: IC EMI FILTER/LINE TERM SOT323-6
• Manufacturer: STMicroelectronics
• Series: ASDr

Specifications of USBUF02W6

• Filter Type: Signal Line
• Mounting Type: Surface Mount
• Termination Style: Surface Mount (SMD,SMT)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Inductance: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-3743-2

USBUFxxW6
2.1
2.2
Application example
Figure 3.
EMI filtering
Current FCC regulations requires that class B computing devices meet specified maximum
levels for both radiated and conducted EMI.
●
●
For the types of devices utilizing the USB, the most difficult test to pass is usually the
radiated EMI test. For this reason the USBUFxxW6 device is aiming to minimize radiated
EMI.
The differential signal (D+ and D-) of the USB does not contribute significantly to radiated or
conducted EMI because the magnetic field of both conductors cancels each other.
The inside of the PC environment is very noisy and designers must minimize noise coupling
from the different sources. D+ and D-must not be routed near high speed lines (clocks
spikes).
Induced common mode noise can be minimized by running pairs of USB signals parallel to
each other and running grounded guard trace on each side of the signal pair from the USB
controller to the USBUF device. If possible, locate the USBUF device physically near the
Downstream port
Downstream port
Radiated EMI covers the frequency range from 30 MHz to 1 GHz.
Conducted EMI covers the 450 kHz to 30 MHz range.
D+
Gnd
D-
D+
Gnd
D-
Implementation of ST solutions for USB ports
D+ in
D+ in
D- in
D- in
Gnd
Gnd
USBDF01W5
USBDF01W5
Ct
Ct
Ct
Ct
Rt
Rt
Rt
Rt
Rd
Rd
Rd
Rd
D+ out
D- out
D+ out
D- out
FULL SPEED CONNECTION
LOW SPEED CONNECTION
D+
D+
D-
D-
CABLE
CABLE
D+
D-
D+
D-
Ct
Ct
USBUF01W6
USBUF01W6
Rt
Rt
D3
D3
D2
D2
Technical information
Gnd
Gnd
3.3V
3.3V
Ct
Ct
Rp
Rp
Rt
Rt
D4
D4
D1
3.3 V
D1
3.3 V
D+
D+
Upstream port
Upstream port
D-
D-
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