SH7261 Datasheet, PDF (113/1348 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7260 Series

Section 4 Clock Pulse Generator (CPG)
4.3 Clock Operating Modes
Table 4.2 shows the relationship between the combinations of the mode control pins (MD_CLK1
and MD_CLK0) and the clock operating modes. Table 4.2 shows the usable frequency ranges in
the clock operating modes.
Table 4.2 Clock Operating Modes
Pin Values
Mode MD_CLK1 MD_CLK0
0
0
0
2
1
0
3
1
1
Clock I/O
PLL Circuit 2 PLL Circuit 1
Source
Output On/Off
On/Off
CKIO Frequency
EXTAL or
CKIO
crystal resonator
ON (×4)
ON (×1, 2, 3, 4) (EXTAL or crystal
resonator) ×4
EXTAL or
CKIO
crystal resonator
ON (×2)
ON (×1, 2, 3, 4, (EXTAL or crystal
6, 8)
resonator) ×2
CKIO

OFF
ON (×1, 2, 3, 4, (CKIO)
6, 8)
• Mode 0
The frequency of the signal received from the EXTAL pin or crystal resonator is quadrupled
by the PLL circuit 2 before it is supplied to the LSI as the clock signal. This enables to use the
external clock of lower frequency. Either a crystal resonator with a frequency in the range from
10 to 15 MHz or an external signal in the same frequency range input on the EXTAL pin may
be used. The frequency range of CKIO is from 40 to 60 MHz.
• Mode 2
The frequency of the signal received from the EXTAL pin or crystal resonator is doubled by
the PLL circuit 2 before it is supplied to the LSI as the clock signal. This enables to use the
external clock of lower frequency. An external signal with a frequency in the range from 10 to
30 MHz or a crystal resonator with 10 to 20 MHz may be used. The frequency range of CKIO
is from 20 to 60 MHz.
• Mode 3
In mode 3, the CKIO pin functions as an input pin and draws an external clock signal. The
PLL circuit 1 shapes its waveform and the setting of the frequency control register multiplies
its frequency before the clock enters the LSI. Frequency between 20 to 60 MHz can be input to
the CKIO pin. For reduced current and hence power consumption, pull up the EXTAL pin and
open the XTAL pin when the LSI is used in mode 3.
Rev. 2.00 Sep. 07, 2007 Page 81 of 1312
REJ09B0320-0200