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MCP3021
DS21805A-page 12
2003 Microchip Technology Inc.
3.0
PIN FUNCTIONS
TABLE 3-1:
PIN FUNCTION TABLE
3.1
VDD and VSS
The VDD pin, with respect to VSS, provides power to the
device, as well as a voltage reference for the conver-
Layout Considerations”, for tips on power and
grounding.
3.2
Analog Input (AIN)
AIN is the input pin to the sample and hold circuitry of
the Successive Approximation Register (SAR) con-
verter. Care should be taken in driving this pin. Refer to
versions, the voltage on this pin can vary from VSS to
VDD.
3.3
Serial Data (SDA)
This is a bidirectional pin used to transfer addresses
and data into and out of the device. It is an open-drain
terminal, therefore, the SDA bus requires a pull-up
resistor to VDD (typically 10 k for 100 kHz and 2 k
“Connecting to the I2C Bus”).
For normal data transfer, SDA is allowed to change only
during SCL low. Changes during SCL high are reserved
for indicating the START and STOP conditions (refer to
3.4
Serial Clock (SCL)
SCL is an input pin used to synchronize the data trans-
fer to and from the device on the SDA pin and is an
open-drain terminal. Therefore, the SCL bus requires a
pull-up resistor to VDD (typically, 10 k for 100 kHz and
2k
for 400 kHz SCL clock speeds. Refer to
For normal data transfer, SDA is allowed to change
only during SCL low. Changes during SCL high are
reserved for indicating the START and STOP
Input”).
Name
Function
VDD
+2.7V to 5.5V Power Supply
VSS
Ground
AIN
Analog Input
SDA
Serial Data In/Out
SCL
Serial Clock In