Hitachi RAS-25CNH2 - Power Circuit for P.W.B.

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4. Power Circuit for P.W.B.
● Fig. 4-1 shows the power circuit for P.W.B. and waveform at each point.
13
14
+
D210
D209
D208
D204
D205
D206
C207
11
12
+
D213
R218
C218
15
16
+
C214
17
18
+
C213
19
20
+
+
8
10
+
C215
+
C210 R213
C208
C209
9
7
6
J98
+17V
0V
REG1
C227
D207
+12V
+5V
0V
-5V
+39V
REG2
Q202
C224
PQ8
C230
C206
1
2
4
3
4
3
1
2
PQ9
R210
R209
C232
R226
C233
D215
R224
R223
PQ9
2
C
1
+
C231
D203
D202
D201
R208
5
3
R203
C201
R204
R202
R201
2 5
3 4
1
+
+
+
IC1
C511
C510
C219
C223
D216
R216
FB1
R215
AC220V
AC240V
3A FUSE
R505
TRANS
FORMER
Fig. 4-1 Power circuit for P.W.B.
● In the power circuit for P.W.B., power voltage for microcomputer, peripheral circuits, and power module
drive and, as well as DV39V, are produced by switching power circuit.
● Switching power circuit performs voltage conversion effectively by switching transistor IC1 to convert
DC300V voltage to high frequency of about 70kHz to 200kHz.
● Transistor IC1 operates as follows:
(1) Shifting from OFF to ON
● DC about 300V is applied from smoothing capacitors C510 Œ and 0511 œ in the control power circuit. With
this power, current flows to pin 4 of IC1 via R201 and R202 and IC1 starts to tum ON. Since voltage in
the direction of arrow generates at point C at the same time, current passing through R208 and D202 is
positive-fed back to IC1.