MCP602

Manufacturer Part NumberMCP602
DescriptionMCP601-2-3-4
ManufacturerN/A
MCP602 datasheet
 


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3.0
APPLICATIONS INFORMATION
The MCP601/2/3/4 family of operational amplifiers are
fabricated on Microchip’s state-of-the-art CMOS
process. They are unity-gain stable and suitable for a
wide range of general purpose applications.
3.1
Input
The MCP601/2/3/4 amplifier family is designed to not
exhibit phase reversal when the input pins exceed the
supply rails. Figure 2-33 shows an input voltage that
exceeds both supplies with no resulting phase
inversion.
The Common Mode Input Voltage Range (V
includes ground in single supply systems (V
does not include V
. This means that the amplifier
DD
input behaves linearly as long as the Common Mode
Input Voltage (V
) is kept within the specified V
CM
limits (V
-0.3V to V
-1.2V at +25°C).
SS
DD
Input voltages that exceed the input voltage range
(V
-0.3V to V
-1.2V at +25°C) can cause excessive
SS
DD
current to flow into, or out of, the input pins. Current
beyond ±2 mA may cause reliability problems.
Applications that exceed this rating must externally
limit the input current with a resistor (R
Figure 3-1.
R
IN
V
IN
MCP60X
(maximum expected V
IN
R
IN
2 mA
V
- (minimum expected V
SS
R
IN
2 mA
FIGURE 3-1:
R
limits the current flow
IN
into an input pin.
3.2
Rail-to-Rail Output
There are two specifications that describe the output
swing capability of the MCP601/2/3/4 family of
operational amplifiers. The first specification, Maximum
Output Voltage Swing, defines the absolute maximum
swing that can be achieved under the specified load
conditions. For instance, the output voltage swings to
within 15 mV of the negative rail with a 25 k
V
/2. Figure 2-33 shows how the output voltage is
DD
limited when the input goes beyond the linear region of
operation.
2003 Microchip Technology Inc.
The second specification that describes the output
swing capability of these amplifiers is the Linear Output
Voltage Swing. This specification defines the maximum
output swing that can be achieved while the amplifier is
still operating in its linear region. To verify linear
operation in this range, the large signal, DC Open-Loop
Gain (A
), is measured at points 100 mV inside the
OL
supply rails. The measurement must exceed the
specified gains in the spec table.
3.3
MCP603 Chip Select
The MCP603 is a single amplifier with Chip Select
(CS). When CS is pulled high, the supply current drops
to -0.7 µA (typ.), which is pulled through the CS pin to
)
CMR
V
. When this happens, the amplifier output is put into
), but
SS
SS
a high impedance state. Pulling CS low enables the
amplifier. If the CS pin is left floating, the amplifier may
not operate properly. Figure 1-1 is the Chip Select
CMR
timing diagram and shows the output voltage, supply
currents and CS current in response to a CS pulse.
Figure 2-27 shows the measured output voltage
response to a CS pulse.
3.4
Capacitive Loads
), as shown in
Driving large capacitive loads can cause stability
IN
problems for voltage feedback op amps. As the load
capacitance increases, the feedback loop’s phase
margin decreases and the closed-loop bandwidth is
reduced. This produces gain peaking in the frequency
response with overshoot and ringing in the step
response.
When driving large capacitive loads with these op
amps (e.g., > 40 pF when G = +1), a small series
resistor at the output (R
feedback loop’s phase margin (stability) by making the
output load resistive at higher frequencies. The
) - V
DD
bandwidth will be generally lower than the bandwidth
with no capacitive load.
)
IN
R
G
FIGURE 3-2:
stabilizes large capacitive loads.
Figure 3-3 gives recommended R
different capacitive loads and gains. The x-axis is the
normalized load capacitance (C
load to
to interpret the plot for arbitrary gains. G
noise gain. For non-inverting gains, G
are equal. For inverting gains, G
(e.g., -1 V/V gives G
MCP601/2/3/4
in Figure 3-2) improves the
ISO
R
ISO
MCP60X
V
OUT
C
L
R
F
Output resistor R
ISO
values for
ISO
/G
) to make it easier
L
N
is the circuit’s
N
and the gain
N
is 1+|Gain|
N
= +2 V/V).
N
DS21314E-page 11