R8C/20 Group, R8C/21 Group 20. Electrical Characteristics
Rev.2.00 Aug 27, 2008 Page 413 of 458
REJ09B0250-0200
NOTES:
1. Topr = -40
°C to 85°C (J version) / -40°C to 125°C (K version), unless otherwise specified.
2. This condition (the minimum value of external power V
CC rise gradient) does not apply if Vpor2 ≥ 1.0 V.
3. To use the power-on reset function, enable voltage monitor 1 reset by setting the LVD1ON bit in the OFS register to 0, the
VW1C0 and VW1C6 bits in the VW1C register to 1 respectively, and the VCA26 bit in the VCA2 register to 1.
4. t
w(por1) indicates the duration the external power VCC must be held below the effective voltage (Vpor1) to enable a power on
reset. When turning on the power for the first time, maintain tw(por1) for 30s or more if -20
°C ≤ Topr ≤ 125°C, maintain tw(por1)
for 3,000s or more if -40
°C ≤ Topr < -20°C.
Figure 20.3 Power-on Reset Circuit Electrical Characteristics
Table 20.8 Power-on Reset Circuit, Voltage Monitor 1 Reset Circuit Electrical Characteristics
(3)
Symbol Parameter Condition Standard Unit
Min. Typ. Max.
V
por1
Power-on reset valid voltage
(4)
−−0.1 V
V
por2 Power-on reset or voltage monitor 1 valid voltage 0 − Vdet1 V
trth External power V
CC rise gradient VCC ≤ 3.6 V
20
(2)
−−mV/msec
V
CC > 3.6 V
20
(2)
− 2,000 mV/msec
× 32
1
fOCO-S
Vdet1
(3)
Vpor1
tw(por1)
Vdet1
(3)
Vpor2
2.0 V
trth
trth
External power Vcc
Internal reset signal
(“L” valid)
Sampling time
(1, 2)
td(Vdet1-A)
× 32
1
fOCO-S
NOTES:
1. When using the voltage monitor 1 digital filter, ensure VCC is 2.0 V or higher during the sampling time.
2. The sampling clock can be selected. Refer to 6. Voltage Detection Circuit for details.
3. V
det1 indicates the voltage detection level of the voltage detection 1 circuit. Refer to 6. Voltage Detection Circuit for details.
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