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2.1.17.3 Battery backup circuit
This system is provided with a battery backup function to be available in case of a service interruption, with a battery connected
to the power unit.
The battery backup circuit is used for functional ON/OFF control with the aid of software.
The software checks the battery voltage (BATT_VOLT) and switches on the required function when the voltage is found to be
above the specified level.
When the function is turned ON and the AC power supply is turned OFF (AC_ON signal turned low), the BATT_ON signal is
turned high and +5V, +3.3V, and +5VCPU (about 8V) are supplied from the battery in the power unit.
Since the supply of +12V is effected, the Back-Lite of the LCD cannot be lit up.
The backup feature is canceled in the following 3 cases:
• When the function is switched OFF with software.
• When forced OFF is executed from hardware in 2 to 5 minutes (set by software) after the start of backup action.
• When the battery voltage lowers and the +5V voltage is found to be below the specified level (approx. 4.2V).
Battery charge is conducted inside the power unit while the AC power supply is ON.
The battery to be used is of the nickel-cadmium type of 7.2V (1.2V × 6 cells), 1500mA.
The control circuit is accommodated in the GATEARRAY.
For more details, refer to the instruction manual for the GATEARRAY and the internal equivalent circuit.
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