R5F21133DFP RENESAS [Renesas Technology Corp], R5F21133DFP Datasheet - Page 29

• Manufacturer Part Number: R5F21133DFP
• Description: 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY/R8C/Tiny SERIES
• Manufacturer: RENESAS [Renesas Technology Corp]

R8C/13 Group
Rev.1.20
REJ09B0111-0120
Figure 5.5 Power-on Reset Circuit
RESET
5.1.3 Power-on Reset Function
Jan 27, 2006
The power-on reset is the function which can reset the microcomputer without the external reset
circuit. The RESET pin should be connected to the V
the power-on reset function, the function turns to active and the microcomputer has its pins, CPU,
and SFR initialized. When a capacitor is connected to the RESET pin, always keep the voltage to the
____________
RESET pin 0.8 V
When the input voltage at the V
chip oscillator clock starts. When the operation counts the low-speed on-chip oscillator clock for 32
times, the internal reset is released. Then the program is executed starting from the address indi-
cated by the reset vector. The initialized pins and registers and the status thereof are the same as in
hardware reset 1 excluding the following bits.
• The D40 bit in the D4INT register turns to “1” automatically (voltage detection interrupt enabled)
• The D46 bit in the D4INT register turns to “1” automatically (hardware reset 2 when going through
Vdet)
Additionally, the hardware reset 2 turns to active after the power-on reset. This is because the VC27
bit in the VCR2 register is set to “1” (voltage detection circuit enabled) after the power-on reset same
as the hardware reset 1, so that hardware reset 2 active conditions are all satisfied including above
D40 and D46 bit conditions.
Figure 5.5 shows the power-on reset circuit. Figure 5.6 shows the power-on reset operation.
V
CC
Vdet detection
f
RING-S
____________
page 18 of 205
CC
or more.
counter
5-bit
Trigger
CC
pin reaches to the Vdet level, count operation of the low-speed on-
S
R
CC
Q
pin via about 5 k
____________
pull-up resistance using
Internal reset signal
5.1 Hardware Reset