HA16117F Series
Selection of External Constants
If the reset duration necessary for the MPU to operate reliably at power-on is known, there is a simple
procedure for selecting external constants, starting from the power-on reset time (tON).
External
constant
values
START
Check watchdog
frequency range
fH and fL
Set power-on
reset time tON
Set reset high
time tRH
Select external
constant CF
• Decide reset
low time (tRL
• Decide reset-clock
off time (tOFF)
)
• Select external
• Select external
constant CR
constants R1 and R2
Figure 4 Procedure for Selecting External Constants
Application Example
SW
R1
510 kΩ
Battery
5 V
regulator
VCC
Tadj
ACC
GND
RES
VCC
Microprocessor
system
RES PORT GND
R2
750 kΩ
P-RUN
HA16117F
CF
CR
CF
0.01 µF
CR
0.1 µF
17
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