REV.-A
2.2.5 +35 V Voltage
Circuit
The back electromotive described in Section 2.2.4.1 causes diode D20 on the secondary side of transformer
TI to conduct, which supplies power. Consequently, the amount of energy stored by the transformer during
a unit period of time becomes equal to the power output. That is:
p
=
+
O f
ton : on-time of Q1
The output voltage is detected by
and
In an AC input switching power circuit, the AC line and
switching circuit are not isolated, but the transformer isolates the DC output (secondary side). Therefore,
photo-coupler
is used to feedback the fluctuating output voltage to the switching circuit while still
isolating it. Refer to Figure 2-17,
This circuit employs a programmable shunt regulator
as a constant voltage element to keep
the output voltage
at 35 V. When Vo goes up, cathode current in
increases so that the
photo-diode receives more current. This action produces an increase in the collector current the
photo-transistor side which becomes a constant voltage signal for Q4, and then the current from
to
the base of is shorted to the O V line to tum off switching transistor
Consequently, the period of time
that
is
applied to winding
on the primary side is cut down, and the voltage induced in winding
T1-3 on the secondary side is reduced.
The switching circuit includes C26 between the cathode terminal and gate terminal for phase correction
(of the amplifier in the
in this case), and prevents an inductance element from entering the feed back
loop and making it oscillate.
T1 +
12
●
D2
R4 ,
1
C7
R5
04
8
●
I
4
v“
Figure 2-17. Output Voltage Stability Circuit
2-23
Summary of Contents for LQ-1060
Page 1: ...EPSON TERMINAL PRINTER L Q 8 6 0 1 0 6 0 TECHNICAL MANUAL ...
Page 5: ...REVISION TABLE REVISION DATE ISSUED I CHANGE DOCUMENT I I 1st issue I v ...
Page 68: ...cc o REV A N N n 1 cc b I al cc u co n4 2 1 Figure 2 14 Main Switching 2 21 ...
Page 79: ...REV A Table 2 20 State of Module 1 1 I W stay E H H L H d O s H H 4 2 32 ...
Page 203: ...Figure 5 6 MONPS MONPSE Board Voltage Waveforms 5 17 ...
Page 204: ...REV A Fiaure 5 6 MONPS MONPSE Board Voltage Waveforms z L 5 18 ...
Page 205: ...Figure 5 6 MONPS MONPSE Board Voltage Waveforms 5 19 ...
Page 248: ...REV A A 3 DRAWINGS 3 J32 J TI g 4 Figure A 27 MONPS Board Component Layout A 34 ...
Page 250: ... 2 1 1 1 1 I A b 2 Ozaz 1202 C O ZZH Z UOEE vu I 1 Figure A 29 MONPS Board Circuit Diagram ...
Page 252: ...L t g Figure A 31 JUNMM Board Component Layout A 38 ...