RESET
and POWER-DOWN
S3C80A5B
8-2
INTERRUPT WITH RESET(INTR)
A non vectored interrupt called Interrupt with reset (INTR) is built in
S3C80A5B to release stop status with system reset. When a falling/rising edge occurs at Port 0 during stop mode,
INTR signal is generated and it makes the system reset pulse. An INTR signal is generated relating to interaction
between Port 0 and operating status. It is enabled by STOP status and occurs by falling/rising edge at port0. So
only when the chip status is "STOP", it is available. If the operating status is not stop status INTR does not occurs.
NOTE
This INTR is supplementary function to make system reset for an application which is using " stop mode"
like remote controller. If an application which is not using "stop mode" , INTR function can be discarded.
WATCHDOG TIMER RESET
The S3C80A5B build a watch-dog timer that can recover to normal operation from abnormal function. Watchdog timer
generates a system reset signal if not clearing a BT-Basic Counter within a specific time by program. System reset
can return to the proper operation of chip.
POWER-ON RESET(POR)
The power-on Reset circuit is built on the S3C80A5B product. During a power-on Reset, the voltage at V
DD
goes to
High level and the Schmitt trigger input of POR circuit is forced to Low level and then to High level. The power-on
reset circuit makes a reset signal whenever the power supply voltage is powering-up and the Schmitt trigger input
senses the Low level. This on-chip POR circuit consists of an internal resistor, an internal capacitor, and a Schmitt
trigger input transistor.
V
DD
System Reset
C
R : On-Chip Resistor
C : On-Chip Capacitor
Schmitt Trigger Inverter
V
SS
Figure 8-2. Power-on Reset Circuit