Epson LQ-510 - A;D Converter Circuit

PRINCIPLES OF OPERATION
REV.-A
2.3.7 A/D CONVERTER CIRCUIT
Figure 2-68 shows the A/D converter circuit. The functions of this converter are as follows:
l Monitors the +24 V line to determine the drive pulse width for the printhead.
0 Monitors the temperature (the resistance value) of the printhead.
l Reads the initial DIP switch settings.
l Reads value of the setting of the bidirectional adjustment (DIP switches).
l Reads the control panel switches.
The circuit’s reference voltage V REF is set, based on shunt regulator TL431 CLPB, R44, and R45, as follows:
VREF =
2.5 v
R45
(R45 + R44) = 4.5 V
NOTE: The shunt regulator reference voltage value is 2.5 V.
With this voltage serving as the reference, the +24 V line is monitored by AN6, the head temperature is
monitored by AN7, and the DIP switches, bidirectional adjustment (DIP switches), and control panel switches
are read using AN0 through AN5.
2-60
LQ-510