MCP6021 Microchip Technology, MCP6021 Datasheet - Page 13

• Manufacturer Part Number: MCP6021
• Description: Rail-to-Rail Input/Output, 10 MHz Op Amps
• Manufacturer: Microchip Technology

4.0
The MCP6021/1R/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.
4.1
The MCP6021/1R/2/3/4 amplifier family is designed to
not exhibit phase inversion when the input pins exceed
the supply voltages. Figure 2-27 shows an input volt-
age exceeding both supplies with no resulting phase
inversion.
The input stage of the MCP6021/1R/2/3/4 family of
devices uses two differential input stages in parallel;
one operates at low common-mode input voltage
(V
topology, the device operates with V
either supply rail (V
The amplifier input behaves linearly as long as V
kept within the specified V
voltage is measured at both V
V
Input voltages that exceed the input voltage range
(V
the input pins. Current beyond ±2 mA introduces
possible reliability problems. Thus, applications that
exceed this rating must externally limit the input current
with an input resistor (R
FIGURE 4-1:
into an input pin.
Total Harmonic Distortion Plus Noise (THD+N) can be
affected by the common mode input voltage (V
shown in Figure 2-3 and Figure 2-6, the input offset
voltage (V
to the PMOS input differential pairs. This change in V
will increase the distortion if the input voltage includes
this transition region. This transition occurs between
V
temperature.
© 2006 Microchip Technology Inc.
DD
DD
CM
CMR
V
IN
+ 0.3V to ensure proper operation.
– 1.0V and V
), while the other operates at high V
) can cause excessive current to flow in or out of
R
R
APPLICATIONS INFORMATION
Rail-to-Rail Input
IN
IN
OS
) is affected by the change from the NMOS
R
IN
(Maximum expected V
V
SS
DD
SS
- (Minimum expected V
MCP602X
– 2.0V, depending on V
– 0.3V to V
R
IN
IN
), as shown in Figure 4-1.
CMR
limits the current flow
2 mA
2 mA
limits. The input offset
CM
DD
CM
= V
+ 0.3V) at +25°C.
IN
up to 0.3V past
) - V
SS
CM
– 0.3V and
IN
DD
. With this
)
V
CM
DD
OUT
CM
). As
and
OS
is
4.2
The Maximum Output Voltage Swing is the maximum
swing possible under a particular output load.
According to the specification table, the output can
reach within 20 mV of either supply rail when
R
information concerning typical performance.
4.3
Driving large capacitive loads can cause stability
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., > 60 pF when G = +1), a small series
resistor at the output (R
feedback loop’s phase margin (stability) by making the
load resistive at higher frequencies. The bandwidth will
be generally lower than the bandwidth with no
capacitive load.
FIGURE 4-2:
stabilizes large capacitive loads.
Figure 4-3 gives recommended R
different capacitive loads and gains. The x-axis is the
normalized load capacitance (C
circuit’s noise gain. For non-inverting gains, G
Signal Gain are equal. For inverting gains, G
1+|Signal Gain| (e.g., -1 V/V gives G
FIGURE 4-3:
for capacitive loads.
L
V
= 10 k . See Figure 2-31 and Figure 2-34 for more
IN
1,000
100
MCP6021/1R/2/3/4
10
Rail-to-Rail Output
Capacitive Loads
10
G
MCP602X
N
Normalized Capacitance; C
+1
100
Output resistor R
Recommended R
ISO
in Figure 4-2) improves the
L
/G
R
1,000
ISO
N
), where G
DS21685C-page 13
N
ISO
L
= +2 V/V).
/G
N
ISO
(pF)
ISO
values for
C
N
L
V
values
10,000
and the
N
OUT
is the
N
is