20
KX-FLB802CX/KX-FLB812CX/KX-FLB802CXS/KX-FLB812CXS
6.3.2. RTC BACKUP CIRCUIT
1. Function
This unit has a lithium battery (BAT600) which works for the Real Time Clock IC (RTC: inside IC604).
The RTC continues to work, backed up by a lithium battery even when the power switch is OFF.
2. RTC Inside (IC604) Backup Circuit Operation
When the power switch is turned ON, power is supplied to the RTC (inside IC604). At this time, the voltage at pin 128 of the
IC604 is +3.3V. When the power switch is turned OFF, the BAT600 supplies power to RTC through DA600.
When the power switch is OFF and the voltage of +3.3V decreases, pin 128 of RTC (IC604) becomes roughly the same volt-
age as the battery voltage. RTC goes into the backup mode, in which the power consumption is lower.
133 XINTOUT O 3.3V INTERRUPT OUTPUT
134 XRD I 3.3V RD SIGNAL
135 XWR I 3.3V WR SIGNAL
136 DB0 I/O 3.3V DATA BUS 0
137 DB1 I/O 3.3V DATA BUS 1
138 DB2 I/O 3.3V DATA BUS 2
139 DB3 I/O 3.3V DATA BUS 3
140 DB4 I/O 3.3V DATA BUS 4
141 DB5 I/O 3.3V DATA BUS 5
142 DB6 I/O 3.3V DATA BUS 6
143 DB7 I/O 3.3V DATA BUS 7
144 3.3V - 3.3V POWER SOURCE(3.3V)
PIN No. SIGNAL I/O POWER SUPPLY VOLTAGE EXPLANATION
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