USB3300 datasheet(46/55 Pages) SMSC

46 / 55 page

Hi-Speed USB Host, Device or OTG PHY with ULPI Low Pin Interface

Datasheet

Revision 1.08 (11-07-07)

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

(RVBUS) 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 VVBUS provided in Table 4.2, "Recommended Operating Conditions". When RVBUS

is installed, the transient must not be allowed to exceed the value of VVBUS for longer than 500 μs.

To protect the VBUS pin against a steady state voltage on the USB connector that exceeds the value

of VVBUS 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

COUT

4.7

μF

Bypass capacitors to ground (<1

ESR) for regulator stability.

Place as close as possible to the

PHY.

CVBUS

See Table 7.2,

"Capacitance

Values at VBUS

of USB

Connector"

Capacitor to ground required by the

USB Specification. SMSC

recommends <1

Ω ESR.

Place near the USB connector.

CBYP

System

dependent.

Bypass capacitor to ground.

Place as close as possible to the

PHY.

CDC_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.

RVBUS

Max of 820

Ω 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

VVBUS for longer than 500 μs

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

120

μF

Device

μF10μF

OTG

μF6.5μF

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