MCP3008-I/SL Microchip Technology, MCP3008-I/SL Datasheet - Page 22

• 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

MCP3004/3008
FIGURE 6-2:
6.2
When the MCP3004/3008 initiates the sample period,
charge is stored on the sample capacitor. When the
sample period is complete, the device converts one bit
for each clock that is received. It is important for the
user to note that a slow clock rate will allow charge to
bleed off the sample capacitor while the conversion is
taking place. At 85°C (worst case condition), the part
will maintain proper charge on the sample capacitor for
at least 1.2 ms after the sample period has ended. This
means that the time between the end of the sample
period and the time that all 10 data bits have been
clocked out must not exceed 1.2 ms (effective clock
frequency of 10 kHz). Failure to meet this criterion may
introduce linearity errors into the conversion outside
the rated specifications. It should be noted that during
the entire conversion cycle, the A/D converter does not
require a constant clock speed or duty cycle, as long as
all timing specifications are met.
6.3
If the signal source for the A/D converter is not a low-
impedance source, it will have to be buffered or
inaccurate conversion results may occur (see
2). It is also recommended that a filter be used to
eliminate any signals that may be aliased back in to the
conversion results, as is illustrated in
an op amp is used to drive, filter and gain the analog
input of the MCP3004/3008. This amplifier provides a
low-impedance source for the converter input, plus a
low-pass filter, which eliminates unwanted high-
frequency noise.
DS21295D-page 22
MCU Transmitted Data
(Aligned with falling
edge of clock)
MCU Received Data
(Aligned with rising
edge of clock)
X = “Don’t Care” Bits
SCLK
D
OUT
D
CS
IN
Maintaining Minimum Clock Speed
Buffering/Filtering the Analog
Inputs
MCU latches data from A/D converter
on rising edges of SCLK
1
0
?
2
Data stored into MCU receive
register after transmission of first
8 bits
SPI Communication with the
0
?
3
0
?
4
0
?
5
0
?
Data is clocked out of A/D
converter on falling edges
6
Figure
0
HI-Z
?
7
0
Start
Bit
?
Start
6-3, where
1
Figure 4-
8
?
SGL/
DIFF
DIFF
SGL
9
MCP3004/3008
D2
?
/
10 11 12 13 14 15
Data stored into MCU receive
register after transmission of
second 8 bits
D2
D1
?
D1
DO
?
DO
Low-pass (anti-aliasing) filters can be designed using
Microchip’s
FilterLab will calculate capacitor and resistors values,
as well as determine the number of poles that are
required for the application. For more information on fil-
tering signals, see AN699, “Anti-Aliasing Analog Filters
for Data Acquisition Systems”.
FIGURE 6-3:
Amplifier is used to implement a second order
anti-aliasing filter for the signal being converted
by the MCP3004.
?
V
using 8-bit segments (Mode 1,1: SCLK idles high).
IN
X
NULL
BIT B9
?
X
R
(Null)
0
1
X
R
0.1 µF
B9 B8
C
C
2
1
2
free
Reference
B8
16
X
4.096V
Don’t Care
R
B7
MCP601
interactive
17 18 19
3
MCP1541
+
X
-
R
The MCP601 Operational
B7 B6 B5 B4 B3 B2 B1 B0
4
B6 B5 B4 B3 B2 B1 B0
Data stored into MCU receive
register after transmission of last
8 bits
© 2008 Microchip Technology Inc.
X
X
20 21 22 23
X
FilterLab
1 µF
IN+
IN-
X
MCP3004
V
X
REF
®
V
X
DD
software.
10 µF
24
X
1 µF