BAT32G1x9 user manual | Chapter 4 Clock generation circuit
102 / 1149
Rev.1.02
Figure 4-21 The clock generation circuit is running when the power is turned on
high speed system
clock
high speed internal
oscillation clock
secondary system
clock
switching via
software
at least
10us
low limit of working voltage range
V
POR
voltage of power source (V
DD
)
power on reset signal
RESETB pin
CPU clock
high speed internal
oscilator clock (f
IH
)
high speed system clock
(fMX) (Scenario of
selecting X1 oscilation)
secondary system clock
(fsub) (Scenario of
selecting XT1 oscilation)
Configure XT1 to start
oscilating via software
Configure X1 to start
oscilating via software
X1 clock oscilation
stablization time.
Note 1
reset
process
0V
①
After power is turned on, an internal reset signal is generated by a power-on reset (POR) circuit.
However, the reset state is maintained by voltage detection circuitry or an external reset until the
operating voltage range shown in the AC characteristics of the data sheet is reached (the figure
above is an example of when using an external reset).
②
If the reset is released, the high-speed internal oscillator automatically begins oscillating.
③
After the reset is released, a voltage stabilization wait and reset process is performed, and then the
CPU starts running with a high-speed internal oscillator clock.
④
The X1 clock or the start oscillation of the XT1 clock must be set by software (see "4.6.2 X1
Oscillation Circuit Setup Example" and "4. 6.3 Example of setup of the oscillation circuit of XT1").
⑤
If you want to switch the CPU clock to the X1 clock or the XT1 clock, you must switch it through the
software settings after waiting for the clock oscillation to stabilize (see "4.6.2 X1.") Example of setting
up an oscillation circuit" and "Example of setting up a 4.6.3 XT1 oscillation circuit").
Note 1
When the reset is released, the oscillation settling time of the X1 clock must be confirmed by the state register
(OSTC)
of the oscillation settling time counter.
Note that if an external clock input from the EXCLK
pin is used, there is no need for oscillation stabilization wait time.