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REV.-A
2.3.6
+
5 VDC Regulator Circuit
Figure 2-14 shows the
+
5 VDC Regulator Circuit.
The
+
5V DC is generated from the
+
24V DC by means of a chopper-type switching regulator circuit
utilizing a TL494. Through the 13-pin of the output control terminal, the TL494 can cause the IC to
operate in either push-pull or parallel mode. Here, the 13-pin is LOW, and parallel action is in effect.
In other words, the operation of the le's two output transistors will be exactly alike.
The IC incorporates an internal oscillating circuit. The oscillating frequency is determined by the external
inputs to pins 5 and 6. In this circuit, the frequency, set by R29 and C25, is about 27kHz.
INPUT
lP401
-02SD
R39
020
--
r
1
A1469
l20
1
~
~
R33
R38
10k
R20
270
0.22
lwx2
R27
T 1
2WX 2
R28
R26
R21
200K
3.9K
20
':~
C26
R3~r;
,j~ZD23
~O~
1.8K
021
~
~D21
HZ5C-2
50Y
Al020
~ERC81
-004
16
15
14
13
12
1 1 10
9
Vcc
V
X
C21
r,+
EAl
1000ltF
:J.
~
10V
(IC20)
I
_EA2
11
620
6-01
R34
-RTF
620
1
2
3
4
5
6
7
8
R36
C25
~29
L - -
0.0
.3K
R37
I?OOK
It
F ..
2K
~t
R35
10K
2200pF
~
-v
Figure 2-14. +5 VDC Regulator Circuit
2-18
OUTPUT
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