Epson Stylus Color 660 Service Manual page 109

EPSON Stylus Color 440/640/740
2.2.4.4 Timer Circuit
A lithium battery is mounted on the main board and calculates how long
the printer is not used. The timer IC starts counting with oscillation
motivated by the crystal oscillator using this battery as a power source.
The following figures show connection of the Timer circuit. The
followings explain about operation of this circuit.

When the printer is on, power is supplied to the Timer IC by
applying +5V quickly through the D1.

This power is also used for the power to oscillator. The
oscillation wave form is input to XI terminal.

Since the oscillation wave form of CR1 is analog wave form, it is
processed into the pulse form in the Timer IC.

When the printer is turned on, the Timer IC outputs power off
time as serial data to the gate array.

Once the printer is turned off, 3VDC of BAT1(lithium battery) is
supplied as power source for the Timer IC through D7.

Since +5V at the power on is higher than +3V of the lithium
battery, the power is not being consumed from the lithium
battery.
CR1
+5
C4
D1
D7
0.1u
Batt1
Figure 2-29. Timer Control Circuit for Stylus Color 440
Chapter 2 Operating Principles
S-3510ANF
(IC5)
2
X O
3 5
CS
X I
6
8
VCC /SCK
4 7
GND /SIO
RM7
E05B44
(IC2)
123
TCE
121
TCLK
124
TDATA
2
CR3
3
+5
8
C4 4
D4
D1
0.1u
Batt1
Figure 2-30. Timer Counter Circuit for Stylus Color 640
+42
+5
Batt1
Figure 2-31. Timer Counter Circuit for Stylus Color 740
Revision A
S-3510ANF
(IC10)
XO
5
CS
XI
6
VCC /SCK
7
GND /SIO
RM7
E05B43
(IC2)
125
TCE
123
TCLK
126
TDATA
RTC-9810
(IC8)
9
Vin 2
/RST
7
Vdd 6
CE
8
5
Vbk
SCLK
4
14
Data
GND
E05B588 25
(IC2)
20
TMCS
21
TMCK
23
TMDATA
71