r5f21346mnfp Renesas Electronics Corporation., r5f21346mnfp Datasheet - Page 66

• Manufacturer Part Number: r5f21346mnfp
• Description: Single-chip Mcus Incorporates The R8c Cpu Core
• Manufacturer: Renesas Electronics Corporation.

R8C/34M Group
R01UH0131EJ0100 Rev.1.00
Jun 21, 2011
5.3
Figure 5.6
When the RESET pin is connected to the VCC pin via a pull-up resistor, and the VCC pin voltage level rises, the
power-on reset function is enabled and the MCU resets its pins, CPU, and SFR. When a capacitor is connected to
the RESET pin, too, always keep the voltage to the RESET pin 0.8VCC or more.
When the input voltage to the VCC pin reaches the Vdet0 level or above, the low-speed on-chip oscillator clock
starts counting. When the low-speed on-chip oscillator clock count reaches 32, the internal reset signal is held “H”
and the MCU enters the reset sequence (refer to Figure 5.3). The low-speed on-chip oscillator clock with no
division is automatically selected as the CPU clock after reset.
Refer to 4. Special Function Registers (SFRs) for the states of the SFR after power-on reset.
To use the power-on reset function, enable voltage monitor 0 reset by setting the LVDAS bit in the OFS register to
0.
Figure 5.6 shows an Example of Power-On Reset Circuit and Operation.
Power-On Reset Function
Notes:
1. V
2. t
Example of Power-On Reset Circuit and Operation
3. To use the power-on reset function, enable voltage monitor 0 reset by setting the
6. Voltage Detection Circuit for details.
voltage (0.5 V) to enable a power-on reset. When turning on the power after it falls
with voltage monitor 0 reset disabled, maintain t
LVDAS bit in the OFS register to 0.
w(por)
det0
indicates the voltage detection level of the voltage detection 0 circuit. Refer to
reset signal
indicates the duration the external power V
Power V
External
4.7 kΩ
(reference)
Internal
V
det0
0.5V
CC
(1)
t
w(por)
VCC
RESET
(2)
w(por)
CC
must be held below the valid
f
OCO-S
for 1 ms or more.
1
× 32
Page 34 of 740
5. Resets