SH7604 Datasheet, PDF (70/633 Pages) Hitachi Semiconductor – Hardware Manual

3.2.4 Inputting an External Clock
Input the external clock from the EXTAL pin or the CKIO pin, depending on the clock mode.
Clock Input from the EXTAL Pin: This can be used in clock modes 0,1, 2, and 3.
CKPREQ/CKM
CKIO
EXTAL
XTAL
Ground level
Output or high
impedance
Open
The CKIO pin is an output in clock
modes 0,1, and 2. In mode 3,
it is high impedance.
External clock input
Figure 3.4 Inputting External Clock
Clock Input from the CKIO Pin: This can be used in clock modes 4, 5, and 6.
CKPREQ/CKM
CKIO
EXTAL
XTAL
CKPREQ/CKM becomes the input
pin for clock pause requests
External clock input
Open
Open
Figure 3.5 Inputting External Clock
3.2.5 Selecting Operating Frequency with a Register
PLL circuit 2 and the frequency modification register can double or quadruple the operating
frequency in clock modes 0 to 3. Figure 3.6 shows a block diagram of PLL circuit 2 and the
frequency modification register.
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