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Section 22 USB Function Module (USB)
22.10.7 Restrictions on Peripheral Module Clock (φ) Operating Frequency
The USB clock select pin (UXSEL) can be used to select the clock source. To set the USB
dedicated clock (cku) at 48 MHz, specify the peripheral module clock (φ) as shown in table 22.8.
Operation cannot be guaranteed if any frequency other than in the following table is specified.
When UXSEL is set to 0, connect USEXTAL to the system power supply (0 V).
The USB operates only in high-speed mode and does not operate in medium-speed mode.
Table 22.8 Selection of Peripheral Module Clock (φ) when USB Connection is Made
UEXTAL Input
Frequency
UXSEL
0
1
8.00 MHz
Rev. 1.00 Mar. 12, 2008 Page 894 of 1178
REJ09B0403-0100
EXTAL Input
USB Dedicated Clock
Frequency
(cku: 48 MHz)
EXTAL × 6
8.00 MHz
UEXTAL × 6
8.50 MHz
φ
EXTAL × 4 (32 MHz)
EXTAL × 4 (34 MHz)
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