Timer Circuit - Epson Stylus Photo Service Manual

EPSON Stylus Photo

2.2.2.4 Timer Circuit

The Timer IC mounted on the C209 main board counts how long the printer is not used.
The lithium-battery (BAT1) is mounted on the board and performs power supply to the Timer IC when the
power is off.
The followings explain about operation of this circuit.

When the printer is on, power is supplied to the Timer IC by applying +5V through
the D4.

This power is also used to oscillate the outer CR1. The oscillation signal is
input to XIN terminal.

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 D1.

While the printer is on, +5V supplied through D4 is higher than +3V of the lithium battery,
therefore, the power is not being consumed from the lithium battery.
2-24
Figure 2-24.Timer Circuit Block Diagram
Rev. A