M2 MC2125PALS Service Manual - page 39

40

Circuit Descriptions

9-1) Source Power Circuit

9-2) Oscillator Circuit

9-3) Reset Circuit 

Terminal

Oscillation Frequency

Xin(#30)

Xout(#31)

4MHz

4MHz

This circuit shows SMPS(Switch Mode Power Supply) which converts AC input voltage (230V, 50Hz) to a high DC voltage

(about 320V). The input AC source power is converted to DC through a wave rectifier (BD1) and the converted DC power

will generate a constant waveform on the switching transformer using a high speed (100KHz) switching motion of

TOP223Y. The D104 will rectify the generated voltage and transform into a steady 12V DC source power used for the

digital display panel and relays. The regulator (KA7805) finally transforms into 5V DC source power for the control board

and sensor’s circuits.

Caution) Be careful to handle this circuit due to high voltages (AC230V, DC300V)

This is oscillator circuit to generate synchronous clocks used to calculate the time for the microprocessor operation.

Note) If the specification of a resonator changes, micro-processor can not work properly.

The reset circuit is to initialize the values RAM 

＆

other sectors of micro-processor. When the power is engaged initially,

the reset voltage becomes “Low,” and it keeps “High” in the normal operation.

Terminal

Voltage

Vcc

RESET

DC 5V

DC 5V