Reset Circuits - Epson Stylus 820 Service Manual

Stylus Color IIs / Stylus 820

2.3.2.1 Reset Circuits

The C160 MAIN Board contains 2 reset circuits: the +5 V monitor reset circuit and the +42 V monitor reset
circuit. The +5 V monitor reset circuit checks the voltage level of the +5 V line, using reset IC PST592D
(IC13), and outputs a reset signal to the E05B08 gate array (IC1) when the voltage level drops below +4.2 V.
The +42 V monitor reset circuit checks the voltage level of the +42 V line, using reset IC M51955B (IC9),
and outputs a reset signal to the CPU. A reset signal is generated when the voltage level drops below +40 V,
and this causes a non-maskable interrupt (NMI).
+42 V
+5 V
Figrure 2-22. Reset Circuit Block Diagram
Rev. A
+5 V
M51955B
(IC9)
6
PST592D
(IC13)
1
CPU (IC2)
INT0
24
RESET
36
E05B08 (IC1)
RESET
PA8
153
Operating Principles
2-21