Intel 8253 - Page 295

Philips Semiconductors Linear Products Product specification
ADC0803/4-1CMOS 8-bit A/D converters
August 31, 1994
564
NOTE:
The V
REF
/2 voltage is either 1/2 the V
CC
voltage or is that which is forced at Pin 9.
Figure 1. Internal Reference Design
V
REF
/2
V
CC
20
V
REF
R
R
DIGITAL
CIRCUITS
ANALOG
CIRCUITS
8 10
9
Figure 2. Offsetting the Zero Scale and Adjusting
the Input Range (Span)
(5V)
V
REF
FS
OFFSET
ADJUST
ZS
OFFSET
ADJUST
330
0.1µF
TO V
REF
/2
TO V
IN
(–)
+
–
VOLTAGE
REFERENCE
V
REF
/2
a. Fixed Reference
b. Fixed Reference Derived from V
CC
c. Optional Full
Scale Adjustment
V
IN
(+)
V
IN
(–)
V
CC
+5V
+
V
REF
/2
10µF
A/D
A/D
V
IN
(+)
V
IN
(–)
V
CC
V
REF
/2
+
10µF
+5V
2k
2k
+5V
2k
2k
100
Figure 3. Absolute Mode of Operation
A/D
V
IN
(+)
V
IN
(–)
V
CC
V
REF
/2
+
10µF
2k
2k
100
FULL SCALE
OPTIONAL
TRANSDUCER
V
CC
Figure 4. Ratiometric Mode of Operation with Optional
Full Scale Adjustment