Panasonic KX-F1200 Service Manual And Technical Manual page 136

KX-F1200 i
10. DIGITAL TAM BACKUP CIRCUIT
1) Function
This unit has a 6.0 volt battery (1.5 voltx4), which works for the digital i AM unit back up. I n_ battery Keeps til_ dlgttal IAM unit_
OGM, ICM and memo recording message in memory if the power is turned off.
2) Circuit Operation
[Power supply]
AC power source turns on, +5 V is supplied to the digital TAM unit as the following path. (Depending on I/O port IC tiC1], the signal
of Bout 2 is controlled by H.)
Power Board --- Q28 -_ DoTAM
AC power source turns off, +5 V is supplied to the digital TAM unit as the following path. (Reset signal is inputted by reset circuit,
the signal of Bout 2 is controlled by L.)
Battery -* CN11 -_ D20 --- R285 ----Q27 _ R283 --, D.TAM
When Back up is necessary, Bout 1 is controlled by H depending on I01.
Situation Bout 1 Bout 2
Power source ON No message in TAM 0 1
Power source ON Message in TAM 1 1
Power source OFF 0 0
1: Hight Level
0: Low Level
[Battery voltage detection]
When detecting battery voltage, to control Bout 3=H depending on IC1. After that to confirm the Batt. Low signal by IO1.
Normal
Battery
voltage check
Bout 3
Output
0
1
1
Batt Low
Input
0
1
Description
Full
Empty
1: Hight Level
0: Low Level
[Battery check (Bout 3 = 1) executes about 20 second interval.]
Bout 3
20sec
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