Hitachi RAS-25QH1 Technische Information Seite 123

DESCRIPTION OF MAIN CIRCUIT OPERATION
MODEL RAS-25QH1, RAS-32QH1, RAS-40QH1
1. Reset Circuit
35V 5V
Q202
Normal : Hi
Reset : Lo
Micro computer
Fig. 1-1
Voltage
PO ena aoe ees 35V DC Line
0 alana? , am i es aaa aaa Vea
, 5V DC Line
BV }---------
Base of Q201
! i}
Power is ON | Power is OFF !
BV Pes sree Se
Collector of Q202
Fig. 1-2
@ The reset circuit initializes the program when power is supplied or power is restored following a power
failure. :
@ RESET "Lo" or SET "Hi" activates the micro computer.
@ Fig.1-2 shows the waveforms in each circuit when power is ON and OFF.
@ When power is supplied, the voltages on the 35V and 5V DC lines rise, and when the 35V DC line
becomes approx. 24V, ZD201 turns on and the voltage at the base of Q201 rises to turn Q201 on.
Since the collector of Q201 goes "Lo" at this time, Q202 turns on and the reset input of the micro
computer goes "Hi". The 5V DC line has already been 5V at this time and the micro computer starts
operation.
@ When power is OFF, the voltage on the 35V DC line drops, and when it is approx. 24V, ZD201 turns off,
Q201 and Q202 turn off, and the reset input of the micro computer goes "Lo" to reset it.
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