Datasheet

MCP621/1S/2/3/4/5/9
DS22188C-page 22 © 2009-2011 Microchip Technology Inc.
3.1 Analog Outputs
The analog output pins (V
OUT
) are low-impedance
voltage sources.
3.2 Analog Inputs
The non-inverting and inverting inputs (V
IN
+, V
IN
–, …)
are high-impedance CMOS inputs with low bias
currents.
3.3 Power Supply Pins
The positive power supply (V
DD
) is 2.5V to 5.5V higher
than the negative power supply (V
SS
). For normal
operation, the other pins are between V
SS
and V
DD
.
Typically, these parts are used in a single (positive)
supply configuration. In this case, V
SS
is connected to
ground and V
DD
is connected to the supply. V
DD
will
need bypass capacitors.
3.4 Calibration Common Mode
Voltage Input
A low-impedance voltage placed at this input (V
CAL
)
will set the op amps’ Common mode input voltage
during calibration. If this pin is left open, the Common
mode input voltage during calibration is approximately
V
DD
/3. The internal resistor divider is disconnected
from the supplies whenever the part is not in
calibration.
3.5 Calibrate/Chip Select Digital Input
This input (CAL/CS, …) is a CMOS, Schmitt-triggered
input that affects the calibration and Low-Power modes
of operation. When this pin goes high, the part is placed
into a Low-Power mode and the output is high-Z. When
this pin goes low, a calibration sequence is started
(which corrects V
OS
). At the end of the calibration
sequence, the output becomes low-impedance and the
part resumes normal operation.
An internal POR triggers a calibration event when the
part is powered on, or when the supply voltage drops
too low. Thus, the MCP622 parts are calibrated, even
though they do not have a CAL/CS
pin.
3.6 Exposed Thermal Pad (EP)
There is an internal connection between the Exposed
Thermal Pad (EP) and the V
SS
pin; they must be
connected to the same potential on the Printed Circuit
Board (PCB).
This pad can be connected to a PCB ground plane to
provide a larger heat sink. This improves the package
thermal resistance (θ
JA
).