4-9. VPP sensor circuit
Protection circuit
To prevent the circuit breakage, the protection circuit watches the voltage level of VCC, VDD and VPP.
When the each voltage level is more than following condition, this circuit cuts the voltage.
VCC,VDD:Incase these voltages are become over voltage, this circuit outputs OSCR�
signal(High signal) and burn out the fuse.
VPP:In case the VPP voltage is more than 15 V or less than 13.9 V, the OVPP.S� level
is inverted and CPU cut the OVPP.ON� signal.
Detection voltage level (Unit: V)
VCC >= +6.5 V
VDD >= +6.5 V
+13.9 V =< VPP <=15.0 V
4-10. Power supply circuit for display
VC
VPGND
This circuit is making the power for display tube.
Voltage level:-VNEst. -31.2 V
VF1 - VF2Est. AC4.85 V
N 11 N |
ACEC
CASIO
