Reset Circuit - Epson Stylus COLOR 880 Service Manual

EPSON Stylus COLOR 880

2.2.2.2 Reset Circuit

Reset circuits are attached on the C378MAIN board to monitor the two
voltages: +5V for the logic line and +42V for the drive line. When each circuit
detects abnormality on the corresponding line, it outputs a reset signal to reset
CPU and ASIC. This function is necessary to prevent the printer from operating
abnormally. IC5 RTC-9810SA, a reset circuit IC, is attached directly on the
main board. This IC monitors both the +5V and +45 lines but can reset them
independently. See Figure 2-18 for the block diagram for the reset circuits.
+5V line reset circuit
The VDD port of the IC5 reset IC monitors the +5V line. When the IC
detects an abnormal voltage level (4.3 V or lower), it outputs a reset signal
from the RST port to CPU and ASIC.
+42V line reset circuit
The VIN port of the IC5 reset IC monitors the +45V line. When the IC
detects an abnormal voltage level (35.5V or lower), it outputs a reset signal
from the VDT port to CPU and ASIC.
NOTE: IC5, also serving as RIC (Real Time Clock), manages timer control when the
printer power is turned off. Power for this operation is supplied from the BAT1.
Operating Principles Electrical Circuit Operating Principles
Figure 2-18. Reset Circuit Block Diagram
Revision A
48