Datasheet

Hi-Speed USB Host, Device or OTG PHY with ULPI Low Pin Interface
Datasheet
Revision 1.1 (01-24-13) 48 SMSC USB3300
DATASHEET
Chapter 7 Application Notes
The USB3300 requires few external components as shown in the application diagrams. In some
applications, the power supplied on the VBUS and GND pins of the USB connector is used as the
source of system power. The USB2.0 standard restricts the voltage at the VBUS pin to a maximum
value of 5.25V. In some applications, it may be required to provide protection to the USB3300 VBUS
pin if the VBUS voltage exceeds the USB2.0 specifications.
One method of protecting the VBUS pin from excessive voltage (transients) is to place a resistor
(R
VBUS
) in series as shown in Figure 7.1, "USB3300 Application Diagram (Peripheral)" and Figure 7.2,
"USB3300 Application Diagram (Host or OTG)". The resistor provides protection against transients that
exceed the value of V
VBUS
provided in Table 4.2, "Recommended Operating Conditions". When R
VBUS
is installed, the transient must not be allowed to exceed the value of V
VBUS
for longer than 500 μs.
To protect the VBUS pin against a steady state voltage on the USB connector that exceeds the value
of V
VBUS
provided in Table 4.2, an Over Voltage Protection (OVP) component can be used as shown
in Figure 7.3, "USB3300 Application Diagram (Peripheral with Over Voltage Protection)".
In addition to the capacitors shown in the application diagrams, each VDD pin should have an
additional capacitor to ground, of value 0.01 or 0.1 μF (not shown for clarity). Approximately equal
numbers of each value should be used.
Table 7.1 Component Values in Application Diagrams
REFERENCE
DESIGNATOR VALUE DESCRIPTION NOTES
C
OUT
4.7μF Bypass capacitors to ground (<1Ω
ESR) for regulator stability.
Place as close as possible to the
PHY.
C
VBUS
See Table 7.2,
"Capacitance
Values at VBUS
of USB
Connector"
Capacitor to ground required by the
USB Specification. SMSC
recommends <1Ω ESR.
Place near the USB connector.
C
BYP
System
dependent.
Bypass capacitor to ground. Place as close as possible to the
PHY.
C
DC_BLOCK
System
dependent.
The USB connector housing may be
AC-coupled to the device ground.
Industry convention is to ground
only the host side of the cable
shield.
R
VBUS
Max of 820Ω in
Host or OTG
applications.
Series resistor to reduce any transient
voltage on the VBUS pin of the
USB3300.
The transient must not be
allowed to exceed the value of
V
VBUS
for longer than 500 μs
ID Pin Okay to leave No Connection
(NC) in device mode.
Table 7.2 Capacitance Values at VBUS of USB Connector
MODE MIN VALUE MAX VALUE
Host 120μF
Device 1μF10μF
OTG 1μF6.5μF