Toshiba TC9349AFG Manual page 30

2. Clock generator control port
The clock generator control port controls the low-speed and high-speed oscillators.
Y1
OSC2
φL15(F)
INV ON
The OSC2 bit controls the on/off setting of the high-speed oscillator. If this bit is set to "1", the high-speed oscillator
ON
is enabled and oscillation is started.
The CK SEL bit converts the CPU operation clock to a low-speed or high-speed oscillator clock. After reset, the CPU
operates with a 75 kHz low-speed clock. When the high-speed clock is to be used, conversion to the high-speed clock takes
place after the OSC2 bit is set to "1" and the high-speed oscillator frequency is stabilized. The INV ON bit can be used
ON
to change the circuit type of the 75 kHz low-speed oscillator. This is usually set to a constant-current type.
Note: The high-speed oscillator clock can be used as the doubler clock for the V
VT (DDCK1/DDCK2).
Note: CK SEL bit control is restricted to conversion of the CPU operation clock and does not affect items such
as PLLs and timers.
Note: The circuit type of the 75 kHz low-speed oscillator is used for the constant-current system. If the crystal
oscillator circuit is set to an inverter type, its output level rises. This circuit type should only be used to
investigate whether or not the tuner characteristic of the crystal oscillator has been affected.
Y2 Y4 Y8
CK
*
ON SEL
30
0: Low-speed oscillator
Selection of CPU clock
1: High-speed oscillator
0: Oscillator stop
High-speed oscillator
1: Oscillator
control
0: Constant-current system
Selection of low-speed
1: Inverter system
oscillator
pin or doubler clock for the
DB
TC9349AFG
2006-02-24