Power-On Reset; Reset Pulse - Epson S1C33210 Technical Manual

II CORE BLOCK: INITIAL RESET

Power-on Reset

Be sure to reset (cold start) the chip after turning on the power to start operating.
Since the #RESET pin is directly connected to an input gate, a power-on reset circuit should be configured outside
the chip.
An initial reset (#RESET = low) turns the high-speed (OSC3) oscillation circuit on. The CPU starts operating with
the OSC3 clock at the rising edge of the reset signal. The high-speed (OSC3) oscillation circuit takes time (10 ms
max. under the standard condition in 3.3 V) for the oscillation to stabilize, therefore initial reset must be released after
an appropriate oscillation-stabilization time has passed in order to start up the CPU without fault. The initial reset
pulse width must be exceeded the oscillation-stabilization time.
Figure 3.2 shows a power-on reset timing chart.
V
DD
#RESET
Maintain the #RESET pin at 0.1•V
least to the oscillation start voltage (3.0 V). Furthermore, maintain the #RESET pin at 0.5•V
high-speed (OSC3) oscillation circuit stabilizes oscillating.
Note: The OSC3 oscillation start time varies due to the elements used, board pattern and operating
environment, therefore allow enough margin for the reset-release time. Refer to "Oscillation
Characteristics", in which an example of oscillation start time is provided.

Reset Pulse

A low pulse can be input to the #RESET pin for resetting the chip being operated.
The minimum reset pulse width is provided in "AC Characteristics". Be sure to input a pulse that has a pulse width
longer than the minimum value.
To reset the chip when the high-speed (OSC3) oscillation circuit is in off status, the pulse width must be extended
until the oscillation stabilizes similarly to the power-on reset. Be aware that a short reset pulse may cause an
operation error.
B-II-3-2
3.0 V (V
0.5V
0.1V
DD
Power on
Figure 3.2 Power-on Reset Timing
or less (low level) after turning the power on until the supply voltage rises at
DD
EPSON
= 3.3 V)
DD
t
(OSC3 oscillation start time) or more
STA3
DD
or less until the
DD
S1C33210 FUNCTION PART