Datasheet

ADS8345
SBAS177C
11
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FIGURE 2. Methods of Driving the ADS8345—Single-Ended
or Differential.
FIGURE 4. Simplified Diagram of the Analog Input.
FIGURE 3. Single-Ended Input—Common Voltage Range
vs V
REF
.
0.5 1.0 1.5 2.0 2.5
V
REF
(V)
Common Voltage Range (V)
–1
0
1
2
3
4
5
2.8
2.1
V
CC
= 5V
Single-Ended Input
0.1
4.9
Converter
+IN
–IN
CH0
CH1
CH2
CH3
A2-A0
(shown 00o
B
)
(1)
SGL/DIF
(shown HIGH)
CH4
CH5
CH6
CH7
COM
NOTE: (1) See Truth Tables, Table I,
and Table II for address coding.
FIGURE 5. Differential Input—Common Voltage Range vs V
REF
.
ADS8345
ADS8345
Single-Ended Input
CHX
COM
CHX+
CHX–
±V
REF
(1)
Differential Input
NOTE: (1) Relative to common-mode voltage.
Common-Mode
Voltage
Common-Mode
Voltage
(typically V
REF
)
±
V
REF
(1)
2
±
V
REF
(1)
2
0.0 1.0 1.5 2.0 2.5
V
REF
(V)
4.2
V
CC
= 5V
0.8
5.2
Common Voltage Range (V)
0
1
2
3
4
5
Differential Input
0.2
REFERENCE INPUT
The external reference sets the analog input range. The
ADS8345 will operate with a reference in the range of 500mV
to +V
CC
/2. Keep in mind that the analog input is the differ-
ence between the CHX input and the COM input, as shown
in Figure 4. For example, in the single-ended mode, a 1.25V
reference with the COM pin at V
CC
/2, the selected input
channel (CH0-CH7) will properly digitize a signal in the range
of (V
CC
/2 – 1.25V) to (V
CC
/2 + 1.25V).