
Resets
Low Voltage Reset (LVR)
MC68HC(7)05H12
—
Rev. 1.0
General Release Specification
MOTOROLA
Resets
73
L
G
R
provided to disable the LVR when the device is expected to normally
operate at low voltages. Note that the V
DD
rise and fall slew rates must
be within the specification for proper LVR operation. If the specification
is not met, the circuit will operate properly following a delay of V
DD
/Slew
rate.
The LVR will generate the RST signal which will reset the CPU and other
peripherals. The low voltage reset will activate the internal pulldown
device connected to the RESET pin.
If any other reset function is active at the end of the LVR reset signal, the
RST signal will remain in the reset condition until the other reset
condition(s) end.
Figure 5-4. Low Voltage Reset
NOTE:
An external capacity at the RST pin increases the reaction time for the
generation of the internal reset and allows V
DD
drops. Refer to
Figure 5-1
.
5.8.1 LVR Operation in WAIT
If enabled, the LVR supply voltage sense option is active during WAIT.
Any reset source can bring the MCU out of WAIT mode.
VRON
VROFF
VDD
RESET
HYSTERESIS