Centralion 400VA, Service Manual, Page: 21 / 33

H. Microcontroller(CPU) Control Circuit
The CPU is supplied by a 5 volts. power supply to pin 25 with ground pin at pin 24. An
extra oscillation circuitry ,(consisting of C03,C04,and crystal XL1) is connected to pin 22
&23. The Blazer series use a CPU type NEC µPD78F9116A and its oscillator frequency is 5.0
MHz.
The pin definition of Blazer CPU is (Figure S-6):
pin 1 : ZERO-CRO control
pin 2 : Buzzer control
pin 3 : SW
pin 4 : +5Volts
pin 5 : load detection
pin 6 : batteryvoltage detection
pin 7 : O/P-V detection
pin 8 : input line detection
pin 9 : ground
pin 10 : no use
pin 11 : inverter PWM signal (DS1)
pin 12 : boost relay control
pin 13 : no use
pin 14 : buck relay control
pin 15 : mani relay control
pin 16 : LED1 control
pin 17 : shutdown
pin 18 : model selection
pin 19 : reset control
pin20 : Vpp (via resistor R11 to ground)
pin 21 : no use
pin 22 : oscillation circuit
pin 23 : oscillation circuit
pin 24 : ground
pin 25 : +5Volts
pin 26 : inverter PWM signal (DS2)
pin 27 : CLMP-OFF control
pin 28 : charge off control
pin 29 : TXD
pin 30 : RXD
To prohibit the CPU from power-up in an unknown state, circuit consisting of Q02 and
associated components, is implemented to force a hardware reset to the CPU whenever the
power is turned on.
Figure S-7 is the relay circuit.The RY01 (main relay) is used for switching between line
and battery modes. When the UPS is changing from battery to line mode, CPU pin 15 is set to
HI to turn on Q03(2SC1815), this actives RY01. Alternatively, if the UPS is changing from
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