2. Reset Circuit
This circuit consists of IC301 (PST575E) and peripheral circuit. This circuit always watches 5V. Output
of this circuit (nRST) is set that if 5V falls below setting level (3.9V). When the 5V rises above voltage,
the reset signal is canceled after a delay of approximately 20 ms. After cancelling, software is started
by CPU.
1
R320
IC301
3
2
PST575E
C305
4
pLPRST
Vdd
5V
3.9V
td
Reset Signal Timing Chart
R321
R105
C103
Q303
Reset Circuit
td
28
IC101
CPU
td=20ms