Datasheet

© 2008 Microchip Technology Inc. DS21298E-page 15
MCP3204/3208
3.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 3-1.
3.1 Digital Ground (DGND)
Digital ground connection to internal digital circuitry.
3.2 Analog Ground (AGND)
Analog ground connection to internal analog circuitry.
3.3 Analog Inputs (CH0 - CH7)
Analog inputs for channels 0 - 7 for the multiplexed
inputs. Each pair of channels can be programmed to be
used as two independent channels in single-ended
mode or as a single pseudo-differential input, where
one channel is IN+ and one channel is IN. See
Section 4.1 “Analog Inputs”, “Analog Inputs”, and
Section 5.0 “Serial communications”, “Serial Com-
munications”, for information on programming the
channel configuration.
3.4 Serial Clock (CLK)
The SPI clock pin is used to initiate a conversion and
clock out each bit of the conversion as it takes place.
See Section 6.2 “Maintaining Minimum Clock
Speed”, “Maintaining Minimum Clock Speed”, for con-
straints on clock speed.
3.5 Serial Data Input (D
IN
)
The SPI port serial data input pin is used to load
channel configuration data into the device.
3.6 Serial Data Output (D
OUT
)
The SPI serial data output pin is used to shift out the
results of the A/D conversion. Data will always change
on the falling edge of each clock as the conversion
takes place.
3.7 Chip Select/Shutdown (CS/SHDN)
The CS/SHDN pin is used to initiate communication
with the device when pulled low and will end a
conversion and put the device in low power standby
when pulled high. The CS
/SHDN pin must be pulled
high between conversions.
TABLE 3-1: PIN FUNCTION TABLE
MCP3204 MCP3208
Symbol Definition
PDIP, SOIC,
TSSOP
PDIP, SOIC
1 1 CH0 Analog Input
2 2 CH1 Analog Input
3 3 CH2 Analog Input
4 4 CH3 Analog Input
— 5 CH4 Analog Input
— 6 CH5 Analog Input
— 7 CH6 Analog Input
— 8 CH7 Analog Input
7 9 DGND Digital Ground
810CS
/SHDN Chip Select/Shutdown Input
911D
IN
Serial Data In
10 12 D
OUT
Serial Data Out
11 13 CLK Serial Clock
12 14 AGND Analog Ground
13 15 V
REF
Reference Voltage Input
14 16 V
DD
+2.7V to 5.5V Power Supply
5, 6 — NC No Connection