Highly Integrated Full Featured Hi-Speed USB 2.0 ULPI Transceiver
Datasheet
5.10
Reference Frequency Selection
The USB3320 is configured for the desired reference frequency by the REFSEL[2], REFSEL[1] and
REFSEL[0] pins. If a pin is connected to VDDIO, the value of “1” is assigned. Connect the pin to
ground to assign a “0.” When using the ULPI Input Clock Mode (60MHz REFCLK Mode), the reference
frequency is always fixed at 60 MHz. Eight reference clock frequencies are available as described in
Table 5.10.
Table 5.10 Configuration to Select Reference Clock Frequency
CONFIGURATION PINS
REFSEL[1]
DESCRIPTION
REFSEL[2]
REFSEL[0]
REFERENCE FREQUENCY
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
52 MHz
38.4 MHz
12 MHz
27 MHz
13 MHz
19.2 MHz
26 MHz
24 MHz
SMSC USB3320
Revision 1.0 (07-14-09)
DATA4S1HEET
SMSC [ SMSC CORPORATION ]
