Samsung S3F80JB - Manual (Page 223)

S3F80JB RESET
8-5
NOTES
1. IPOR / LVD Control Bit is one of smart option bits assigned address 03FH. User can enable / disable
LVD in the stop mode by manipulating this bit. When the value is ‘1’, LVD always operate in the
normal and stop mode. When the value is ‘0’, LVD is disabled in the stop mode. But, LVD is enabled
in the normal operating mode.
2. CPU can enter stop mode by setting STOPCON (Stop Control Register) into 0A5H before execution
STOP instruction.
3. This signal is output of IPOR/LVD Control Bit setting. So that is one of two cases; one is LVD enable
in STOP mode, the other is LVD disable in STOP mode.
4. This signal is output relating to STOP mode. If STOPCON has 0A5H, and STOP instruction is
executed, that output signal makes S3F80JB enter STOP mode. So that is one of two statuses; one is
STOP mode, the other is not STOP mode.
5. In S3F80JB, one between LVD and IPOR is selected as reset source by IPOR / LVD Control Bit
setting value of smart option in the stop mode. If the setting value is ‘0’, LVD can be disabled by
STOP instruction. Instead of LVD, IPOR is enabled. If the setting value is ‘1’, LVD is enabled
regardless of executing STOP instruction and IPOR is disabled.
INTERNAL POWER-ON RESET
The power-on reset circuit is built on the S3F80JB 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. IPOR can be enabled by setting IPOR / LVD control bit of smart option to ‘0’.
V DD
System Reset
C
Schmitt Trigger Inverter
V SS
R: 3000k
Ω On-Chip Internal Resistor
C: 340pF On-Chip Internal Capacitor
Figure 8-4. Internal Power-On Reset Circuit