upd78f0730 Renesas Electronics Corporation., upd78f0730 Datasheet - Page 98

• Manufacturer Part Number: upd78f0730
• Description: 8-bit Single-chip Microcontroller
• Manufacturer: Renesas Electronics Corporation.

When 2.7 V/1.59 V POC Mode Is Set (Option Byte: POCMODE = 1)
98
oscillation clock (f
Internal reset signal
Internal high-speed
(when X1 oscillation
system clock (f
<1> When the power is turned on, an internal reset signal is generated by the power-on-clear (POC) circuit.
Note
Cautions 1. It is not necessary to wait for the oscillation stabilization time when an external clock input
Remark While the microcontroller is operating, a clock that is not used as the CPU clock can be stopped via
<2> When the power supply voltage exceeds 2.7 V (TYP.), the reset is released and the internal high-speed
<3> After the reset is released and reset processing is performed, the CPU starts operation on the internal high-
<4> Set the start of oscillation of the X1 clock via software (see (1) in 5.6.1 Example of controlling high-speed
<5> When switching the CPU clock to the X1 clock, wait for the clock oscillation to stabilize, and then set
Power supply
voltage (V
High-speed
CPU clock
selected)
oscillator automatically starts oscillation.
speed oscillation clock.
system clock).
switching via software (see (3) in 5.6.1 Example of controlling high-speed system clock).
When releasing a reset (above figure) or releasing STOP mode while the CPU is operating on the internal
high-speed oscillation clock, confirm the oscillation stabilization time for the X1 clock using the oscillation
stabilization time counter status register (OSTC). If the CPU operates on the high-speed system clock (X1
oscillation), set the oscillation stabilization time when releasing STOP mode using the oscillation
stabilization time select register (OSTS).
DD
0 V
RH
XH
software settings.
stopped by executing the STOP instruction (see (4) in 5.6.1 Example of controlling high-speed
system clock and (3) in 5.6.2 Example of controlling internal high-speed oscillation clock).
)
)
)
2. For the
Figure 5-13. Clock Generator Operation When Power Supply Voltage Is Turned On
<1>
from the EXCLK pin is used.
(POCMODE = 1).
µ
PD78F0730, be sure to set the 2.7 V/1.59 V POC mode by using the option byte
The internal high-speed oscillation clock and high-speed system clock can be
Waiting for oscillation
accuracy stabilization
2.7 V (TYP.)
Preliminary User’s Manual U19014EJ1V0UD
CHAPTER 5 CLOCK GENERATOR
Starting X1 oscillation
is specified by software.
<2>
<3>
Reset processing
oscillation stabilization time:
(20 s (TYP.))
Internal high-speed
oscillation clock
µ
2
11
/f
X1 clock
X
to 2
16
/f
X
Note
<4>
Switched by
software
High-speed system clock