MCP3301-CI/SL Microchip Technology, MCP3301-CI/SL Datasheet - Page 18

• Manufacturer Part Number: MCP3301-CI/SL
• Description: 13-BIT ADC, DIFF INPUTS, SINGLE CHANNEL, -40C to +85C, 14-SOIC 150mil, TUBE
• Manufacturer: Microchip Technology

MCP3301
FIGURE 6-5:
for gain and also buffers the input from any high
impedance sources.
This circuit shows that some headroom will be lost due
to the amplifier output not being able to swing all the
way to the rail. An example would be for an output
swing of 0V to 5V. This limitation can be overcome by
supplying a V
mode voltage. Using a 2.048V reference for the A/D
converter, while biasing the input signal at 2.5V solves
the problem. This circuit is shown in Figure 6-6.
FIGURE 6-6:
amplifier output swing limitation.
DS21700C-page 18
1 kΩ
1 kΩ
V
V
IN
IN
1 µF
1 µF
REF
10 kΩ
10 kΩ
MCP6022
MCP606
1 MΩ
1 MΩ
+
+
-
-
that is slightly less than the common
1 µF
1 µF
Adding an amplifier allows
Circuit solution to overcome
V
V
IN+
IN-
IN+
IN-
MCP1525
MCP1525
OUT
OUT
V
MCP3301
MCP3301
2.048V
REF
V
V
0.1 µF
0.1 µF
IN
IN
V
REF
V
V
DD
DD
0.1 µF
0.1 µF
10 kΩ
= 5V
= 5V
6.4
The common mode input range has no restriction and
is equal to the absolute input voltage range: V
to V
mode voltage has a limited swing if the entire range of
the A/D converter is to be used. Figure 6-7 and
Figure 6-8 show the relationship between V
common mode voltage. A smaller V
flexibility in a common mode voltage. V
to 400 mV and exhibits less than 0.1 LSB change in
DNL and INL. See Figure 2-9 and Figure 2-12 for char-
acterization graphs that illustrate this performance
relationship.
FIGURE 6-7:
Full Differential input signal versus V
FIGURE 6-8:
versus V
DD
-1
5
4
3
2
1
0
-1
0.25
5
4
3
2
1
0
0.25
+0.3V. However, for a given V
Common Mode Input Range
REF
1.0
0.5
for Pseudo Differential Input.
Common Mode Range of
Common Mode Range
© 2007 Microchip Technology Inc.
V
V
REF
REF
2.5
1.25
4.05V
(V)
0.95V
4.05V
0.95V
(V)
REF
REF
REF
allows for wider
, the common
REF
4.0
2.0
levels down
REF
V
.
V
DD
DD
SS
and the
= 5V
2.8V
2.3V
2.3V
2.8V
= 5V
-0.3V
5.0
2.5