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Protection circuit
To prevent the Fiscal ROM breakage, the protection circuit watches the voltage lebel of
VCC,VDD,FVCC and VPP.
When the each voltage level is more than following condition, this circuit cuts the voltage.
VCC,VDD and FVCC : In case these voltages are become over voltage, this circuit
outputs "SCR" signal(High signal) and burn out the fuse.
VPP : In case the VPP voltage is more than 15V or less than 13.9V, the "VPP.S" level is inverted and CPU
cut the "VPP.ON" signal.
Detection voltage level (Unit : V)
VCC >= +6.5V
VDD >= +6.5V
FVCC >= +7.7V
+13.9V =< VPP <=15.0V
6-11. Power supply circuit for display
This circuit is making the power for display tube.
Voltage level : -VN Est. -31.2V
VF1 - VF2 Est. AC4.85V
GND
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