MCP3008-I/SL Microchip Technology, MCP3008-I/SL Datasheet - Page 23

• Manufacturer Part Number: MCP3008-I/SL
• Description: IC ADC 10BIT 2.7V 8CH SPI 16SOIC
• Manufacturer: Microchip Technology

Specifications of MCP3008-I/SL

• Number Of Converters: 1
• Package / Case: 16-SOIC (0.154", 3.90mm Width)
• Number Of Bits: 10
• Sampling Rate (per Second): 200k
• Data Interface: Serial, SPI™
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Architecture: SAR
• Conversion Rate: 200 KSPs
• Resolution: 10 bit
• Input Type: Voltage
• Snr: 200 dB
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Package: 16SOIC N
• Sampling Rate: 200 KSPS
• Number Of Adcs: 1
• Number Of Analog Inputs: 8|4
• Digital Interface Type: Serial (4-Wire, SPI)
• Polarity Of Input Voltage: Unipolar
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

6.4
When laying out a printed circuit board for use with
analog components, care should be taken to reduce
noise wherever possible. A bypass capacitor should
always be used with this device and should be placed
as close as possible to the device pin. A bypass
capacitor value of 1 µF is recommended.
Digital and analog traces should be separated as much
as possible on the board, with no traces running
underneath the device or bypass capacitor. Extra
precautions should be taken to keep traces with high-
frequency signals (such as clock lines) as far as
possible from analog traces.
Use of an analog ground plane is recommended in
order to keep the ground potential the same for all
devices on the board. Providing V
devices in a “star” configuration can also reduce noise
by eliminating return current paths and associated
errors (see
tips when using A/D converters, refer to AN688,
“Layout Tips for 12-Bit A/D Converter Applications”.
FIGURE 6-4:
‘Star’ configuration in order to reduce errors
caused by current return paths.
6.5
The MCP3004/3008 devices provide both digital and
analog ground connections to provide additional
means of noise reduction. As is shown in
the analog and digital circuitry is 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.
© 2008 Microchip Technology Inc.
Device 1
Layout Considerations
Utilizing the Digital and Analog
Ground Pins
Figure
Device 2
6-4). For more information on layout
Connection
V
DD
V
DD
traces arranged in a
Device 3
DD
Device 4
connections to
Figure
6-5,
If no ground plane is utilized, both grounds must be
connected to V
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. Following these
steps will reduce the amount of digital noise from the
rest of the board being coupled into the A/D converter.
FIGURE 6-5:
Digital Ground Pins.
Digital Side
-SPI Interface
-Shift Register
-Control Logic
SS
DGND
MCP3004/3008
Analog Ground Plane
on the board. If a ground plane is
MCP3004/08
V
Substrate
5 - 10Ω
DD
Separation of Analog and
Analog Side
-Sample Cap
-Capacitor Array
-Comparator
AGND
DS21295D-page 23
0.1 µF