Datasheet

MCP3021
DS21805B-page 12  2003-2013 Microchip Technology Inc.
3.0 PIN FUNCTIONS
TABLE 3-1: PIN FUNCTION TABLE
3.1 V
DD
and V
SS
The V
DD
pin, with respect to V
SS
, provides power to the
device, as well as a voltage reference for the conver-
sion process. Refer to Section 6.4, “Device Power and
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
Section 6.1, “Driving the Analog Input”. For proper con-
versions, the voltage on this pin can vary from V
SS
to
V
DD
.
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 V
DD
(typically 10 k for 100 kHz and 2 k
for 400 kHz SCL clock speeds (refer to Section 6.2,
“Connecting to the I
2
C 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
Section 5.1, “I
2
C Bus Characteristics”).
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 V
DD
(typically, 10 k for 100 kHz and
2k for 400 kHz SCL clock speeds. Refer to
Section 6.2, “Connecting to the I
2
C 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 Section 6.1, “Driving the Analog
Input”).
Name Function
V
DD
+2.7V to 5.5V Power Supply
V
SS
Ground
AIN Analog Input
SDA Serial Data In/Out
SCL Serial Clock In