Reference Voltage Generation Circuit - Epson LQ-1050 Technical Manual

2.3.5.1 Reference Voltage Generation Circuit

Figure 2-41 shows the generation circuit for reference voltage
in the CPU. This circuit employs a programmable shunt regulator
supply.
A
.
Reference voltage
TL431 .
to
= +
Using the above formula,
+5
o
u
Fig. 2-41. Reference Voltage
depends on the combination of resistors
+ = 4.75
'
is stabilized at about 4.75 V.
(4.75
+12
= 2
= 2.495
2-41
VDC) used in the A/D converter
1 (CY 1 ) for the reference voltage
Circuit
and connected in parallel