Control Circuitry; Reset Circuit - Epson TM-U200 Series Technical Manual

C o n fid e n tia l
+5 VDC control circuit
The +5 V regulator circuit switches the +24 V power input and converts it to +5 V. The switching
regulator IC (U1) switches the +24 V input, smooths it via C1, and outputs +5 V. Power for the
RS-232 is generated by the internal charge-up circuit on the RS-232 interface driver.
R59
U5
30 WDTOUT
P80 WDTOUT
73 +24COM SW
P51/T04
74 CRCOM SW
P52/T05
76 PFCOM SW
P53/INT1/TI4
CN1
F1
1
+30V 1
2
GND 2
3
N . C 3
4
F . G SH
F . G

Control Circuitry

Reset circuit

The reset circuit is used to prevent the CPU from operating erratically and the print head from
printing unexpectedly during the period of unstable voltage immediately after power is turned
on. To accomplish this, the OUT terminal output (pin 6) of the reset IC (U9) is supplied to the
CPU (U5) as the RESET input signal (pin 21).
The reset IC (U9) monitors the +5 V voltage. When the voltage is 4.5 V or more, reset is released
for the CPU and other components, and the printer becomes ready.
In addition, the C terminal (pin 5) of the reset IC (U9) is connected to the reset signal (DSR signal
or pin 25 input signal) from the host interface via DIP switches 2-7 and 2-8. If a reset signal is
applied to this pin, reset IC output goes LOW and the CPU and other components are reset.
2-18 Mechanism Configuration and Operating Principles
{5 V
QM115
3 2
1
4 5
Q1
QM110 4
3 2
5 1
D6
+24DT
C12 C11
L1
P.G
GND
BETA
Figure 2-20 Power supply circuit diagram
R5
G
N
D
+24DT
D47
+
R6
C14
_
DM128
R7
+
C10
_
R17
Power switch
SW1
Power switch
+5I 1 2
D4
U2
5 3
VIN VOUT
2 4
SW SEN
+ +
C45 C16
_ _
1
GND
D3
U3
5 3
VIN VOUT
G
2 4
N
SW SEN
D +
C6 C7
1 _
D5
U4
5 3
VIN VOUT
G
2 4
N
SW SEN
D +
C8
C9
1 _
U1
R114
10 1
IN OUT
6
LIN
+
G
_
C3 5
C2 C1
+24DT
+24A
HEAD COM
A / C COM
DKD COM
+24B
CR COM
nPFCOM
nPFCOM
+24C
PF COM
{5 V
1
+
_
C5
Rev. A