RL78/G10 CHAPTER 5 CLOCK GENERATOR
R01UH0384EJ0311 Rev. 3.11 92
Dec 22, 2016
Figure 5-12. Clock Generator Operation When Power Supply Voltage Is Turned On
Note 1
Power supply
voltage (V
DD
)
Internal reset signal
CPU clock
High-speed on-chip
oscillator clock (f
IH
)
High-speed
system clock (f
MX
)
(when X1 oscillation
selected)
SPOR reset
processing
Note 3
Switched by software
High-speed system clockHigh-speed on-chip oscillator
clock
X1 clock
oscillation stabilization time
Note 2
Starting X1 oscillation
is specified by software.
<4>
<5>
<1>
<2>
<3>
0 V
SPOR release
reset voltage
<1> When the power is turned on, an internal reset signal is generated by the selectable power-on-reset (SPOR)
circuit.
<2> When the power supply voltage exceeds detection voltage of the SPOR circuit, the reset is released and the
high-speed on-chip oscillator automatically starts oscillation.
<3> The CPU starts operation on the high-speed on-chip oscillator clock after waiting for the voltage to stabilize and
an SPOR reset processing have been performed after reset release.
<4> Set the start of oscillation of the X1 clock via software (see 5.6.2 Example of setting X1 oscillation clock).
<5> When switching the CPU clock to the X1 clock, wait for the clock oscillation to stabilize, and then switch the clock
via software.
Notes 1. The reset processing time includes the oscillation accuracy stabilization time of the high-speed on-chip
oscillator clock.
2. When releasing a reset, confirm the oscillation stabilization time for the X1 clock using the oscillation
stabilization time counter status register (OSTC).
3. For SPOR reset processing time, see CHAPTER 18 SELECTABLE POWER-ON-RESET CIRCUIT.
Caution When an external clock input from the EXCLK pin is in use, oscillation stabilization time is
unnecessary.
To Next Page
Loading...
Need help?
General
