Datasheet

 2011 Microchip Technology Inc. DS21697F-page 21
MCP3302/04
5.7 Utilizing the Digital and Analog
Ground Pins
The MCP3302/04 devices provide both digital and
analog ground connections to provide another means
of noise reduction. As shown in Figure 5-11, the analog
and digital circuitry are separated internal to the device.
This reduces noise from the digital portion of the device
being coupled into the analog portion of the device. The
two grounds are connected internally through the
substrate which has a resistance of 5 -10Ω.
If no ground plane is utilized, then both grounds must
be connected to V
SS
on the board. If a ground plane is
available, both digital and analog ground pins should
be connected to the analog ground plane. If both an
analog and a digital ground plane are available, both
the digital and the analog ground pins should be
connected to the analog ground plane, as shown in
Figure 5-11. Following these steps will reduce the
amount of digital noise from the rest of the board being
coupled into the A/D Converter.
FIGURE 5-11: Separation of Analog and
Digital Ground Pins.MCP3302/04.
MCP3302/04
Analog Ground Plane
DGND
AGND
V
DD
0.1 µF
Substrate
5 - 10 
Digital Side
-SPI Interface
-Shift Register
-Control Logic
Analog Side
-Sample Cap
-Capacitor Array
-Comparator