MCP3021
3.3
Serial Data (SDA)
3.0
PIN FUNCTIONS
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
TABLE 3-1:
Name
PIN FUNCTION TABLE
Function
resistor to V
(typically 10 kΩ for 100 kHz and 2 kΩ
DD
V
+2.7V to 5.5V Power Supply
Ground
Analog Input
Serial Data In/Out
Serial Clock In
DD
for 400 kHz SCL clock speeds (refer to Section 6.2,
2
V
“Connecting to the I C Bus”).
SS
AIN
SDA
SCL
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
2
Section 5.1, “I C Bus Characteristics”).
3.1
V
and V
DD SS
3.4
Serial Clock (SCL)
The V pin, with respect to V , provides power to the
DD
SS
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
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.
pull-up resistor to V (typically, 10 kΩ for 100 kHz and
DD
2 kΩ for 400 kHz SCL clock speeds. Refer to
2
Section 6.2, “Connecting to the I C Bus”).
3.2
Analog Input (AIN)
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”).
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 to
SS
V
.
DD
DS21805A-page 12
2003 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
