Datasheet

MCP3302/04
DS21697F-page 14  2011 Microchip Technology Inc.
3.7 Analog Ground (AGND)
Ground connection to internal analog circuitry. To
ensure accuracy, this pin must be connected to the
same ground as DGND. If an analog ground plane is
available, it is recommended that this device be tied to
the analog ground plane in the circuit. See Section 5.6
“Layout Considerations” for more information
regarding circuit layout.
3.8 Voltage Reference (V
REF
)
This input pin provides the reference voltage for the
device, which determines the maximum range of the
analog input signal and the LSB size.
The LSB size is determined according to the equation
shown below. As the reference input is reduced, the
LSB size is reduced accordingly.
EQUATION 3-1:
When using an external voltage reference device, the
system designer should always refer to the
manufacturer’s recommendations for circuit layout.
Any instability in the operation of the reference device
will have a direct effect on the accuracy of the ADC
conversion results.
3.9 Power Supply (V
DD
)
The device can operate from 2.7V to 5.5V, but the data
conversion performance is from 4.5V to 5.5V supply
range. To ensure accuracy, a 0.1 µF ceramic bypass
capacitor should be placed as close as possible to the
pin. See Section 5.6 “Layout Considerations” for
more information regarding circuit layout.
LSB Size =
2 x V
REF
8192