
RL78/G1P
CHAPTER 18 POWER-ON-RESET CIRCUIT
R01UH0895EJ0100 Rev.1.00
623
Nov 29, 2019
Figure 18-2. Timing of Generation of Internal Reset Signal by Power-on-reset Circuit
and Voltage Detector (3/3)
(3) When LVD is reset mode (option byte 000C1H: LVIMDS1 = 1, LVIMDS0 = 1)
0 V
Internal reset signal
V
LVD
Reset period
(oscillation stop)
Supply voltage (V
DD
)
Lower limit voltage for guaranteed operation
V
PDR
= 1.50 V (TYP.)
V
POR
= 1.51 V (TYP.)
CPU operation stops
High-speed
system clock (f
MX
)
(when X1 oscillation
is selected)
High-speed on-chip
oscillator clock (f
IH
)
LVD reset processing time
Note 3
Reset
period
(oscillation
stop)
LVD reset processing time
Note 4
Voltage stabilization wait + POR reset processing time
1.64 ms (TYP.), 3.10 ms (MAX.)
Voltage stabilization wait + POR reset processing time
1.64 ms (TYP.), 3.10 ms (MAX.)
Normal operation
(high-speed on-chip
oscillator clock)
Note 1
Operation stops
Wait for oscillation
accuracy stabilization
Note 2
Wait for oscillation
accuracy stabilization
Note 2
LVD reset processing time
Note 3
Starting oscillation is
specified by software
Starting oscillation is
specified by software
Starting oscillation is
specified by software
Wait for oscillation
accuracy stabilization
Note 2
Normal operation
(high-speed on-chip
oscillator clock)
Note 1
Notes 1.
The high-speed on-chip oscillator clock and a high-speed system clock can be selected as the CPU clock.
To use the X1 clock, use the oscillation stabilization time counter status register (OSTC) to confirm the
lapse of the oscillation stabilization time.
2.
The internal reset processing time includes the oscillation accuracy stabilization time of the high-speed on-
chip oscillator clock.
3.
The time until normal operation starts includes the following LVD reset processing time after the LVD
detection level (V
LVD
) is reached as well as the voltage stabilization wait + POR reset processing time after
the V
POR
(1.51 V, typ.) is reached.
LVD reset processing time: 0 ms to 0.0701 ms (max.)
4.
When the power supply voltage is below the lower limit for operation and the power supply voltage is then
restored after an internal reset is generated only by the voltage detector (LVD), the following LVD reset
processing time is required after the LVD detection level (V
LVD
) is reached.
LVD reset processing time: 0.0511 ms (typ.), 0.0701 ms (max.)
Remarks 1.
V
LVD
: LVD
detection
voltage
V
POR
: POR power supply rise detection voltage
V
PDR
: POR power supply fall detection voltage
2.
When the LVD interrupt mode is selected (option byte 000C1H: LVIMD1 = 0, LVIMD0 = 1), the time until
normal operation starts after power is turned on is the same as the time specified in Note 2 of
Figure
18-2 (3)