Panasonic KX-FLM551 - 7.3.3. SRAM AND RTC BACKUP CIRCUIT

No. PIN NAME I/O
POWER SUPPLIED
VOLTAGE
EXPLANATION
132 3.3V 3.3V POWER SOURCE(+3.3V)
133 VSS GND POWER SOURCE(GND)
134 5V 5V POWER SOURCE(+5V)
135 ECLK O 5V ELECTRICAL VOLUME
IC
CONTROL
136 ESTB O 5V ELECTRICAL VOLUME
IC
CONTROL
137 EDATA O 5V ELECTRICAL VOLUME
IC
CONTROL
138 IOP40 I/O 5V INPUT PORT(HOOK)
139 IOP41 I/O 5V INPUT PORT(VOX)
140 IOP42 I/O 5V OUTPUT PORT(ALC)
141 IOP43 I/O 5V OUTPUT PORT(P-
SHORT)
142 IOP44 I/O 5V OUTPUT PORT(CID)
143 IOP45 I/O 5V INPUT PORT(EX-HOOK)
144 IOP46 I/O 5V OUTPUT PORT(AGC)
145 IOP47 I/O 5V OUTPUT PORT(BREAK)
146 VSS GND POWER SOURCE(GND)
147 5V 5V POWER SOURCE(+5V)
148 IOP50 I/O 5V OUTPUT PORT(
SPMUTE)
149 IOP51 I/O 5V OUTPUT PORT(RLY)
150 IOP52 I/O 5V NOT USED
151 IOP53 I/O 5V NOT USED
152 IOP54 I/O 5V NOT USED
153 IOP55 I/O 5V OUTPUT PORT(
SENCTL5)
154 IOP56 I/O 5V INPUT PORT(REGIST)
155 IOP57 I/O 5V OUTPUT PORT(DEV)
156 TRS O 5V TRANSCRIPTION
CLOCK
157 VSS GND POWER SOURCE(GND)
158 5V 5V POWER SOURCE(+5V)
159 TEST0 I 3.3V NOT USED
160 TEST1 I 3.3V NOT USED
7.3.3. SRAM AND 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
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