MCP6271 Microchip Technology, MCP6271 Datasheet - Page 11

• Manufacturer Part Number: MCP6271
• Description: 170 uA, 2 MHz Rail-to-Rail Op Amp
• Manufacturer: Microchip Technology

4.0
The MCP6271/2/3/4/5 family of op amps is manufac-
tured using Microchip’s state-of-the-art CMOS process,
specifically designed for low-cost, low-power and
general purpose applications. The low supply voltage,
low quiescent current and wide bandwidth makes the
MCP6271/2/3/4/5
applications.
4.1
The MCP6271/2/3/4/5 op amps are designed to
prevent phase reversal when the input pins exceed the
supply voltages. Figure 4-1 shows the input voltage
exceeding the supply voltage without any phase
reversal.
FIGURE 4-1:
No Phase Reversal.
The input stage of the MCP6271/2/3/4/5 op amps use
two differential CMOS input stages in parallel. One
operates at low common mode input voltage (V
the other at high V
operates with V
below V
at V
operation.
Input voltages that exceed the absolute maximum volt-
age (V
current to flow into or out of the input pins. Current
beyond
Applications that exceed this rating must be externally
limited with a resistor, as shown in Figure 4-2.
 2004 Microchip Technology Inc.
CM
-1
6
5
4
3
2
1
0
SS
= V
SS
-15
APPLICATION INFORMATION
Rail-to-Rail Inputs
±2 mA
– 0.3V to V
. The Input Offset Voltage (V
SS
-14
– 0.3V and V
CM
-13
can
CM
up to 0.3V above V
V
-12
DD
ideal
IN
. With this topology, the device
The MCP6271/2/3/4/5 Show
Time (1 ms/div)
+ 0.3V) can cause excessive
cause
-11
DD
-10
+ 0.3V to ensure proper
for
V
reliability
OUT
-9
battery-powered
-8
OS
) is measured
DD
-7
V
G = +2 V/V
DD
problems.
and 0.3V
= 5.0V
-6
CM
) and
-5
FIGURE 4-2:
Resistor (R
4.2
The output voltage range of the MCP6271/2/3/4/5 op
amps is V
when R
V
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. A unity-gain buffer (G = +1) is the most
sensitive to capacitive loads, though all gains show the
same general behavior.
When driving large capacitive loads with these op
amps (e.g., > 100 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
bandwidth will be generally lower than the bandwidth
with no capacitive load.
FIGURE 4-3:
stabilizes large capacitive loads.
Figure 4-4 gives recommended R
ent 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
DD
V
IN
V
= 5.5V. Refer to Figure 2-16 for more information.
IN
R IN
R IN
Rail-to-Rail Output
Capacitive Loads
L
DD
= 10 k
MCP6271/2/3/4/5
IN
MCP627X
+
–
– 15 mV (min.) and V
----------------------------------------------------------------------------------------
V SS
------------------------------------------------------------------------------------- -
Maximum expected V IN
).
R
IN
–
is connected to V
Minimum expected V IN
Input Current Limiting
Output Resistor, R
ISO
–
MCP627X
+
in Figure 4-3) improves the
2 mA
2 mA
R
L
ISO
/G
ISO
C
N
SS
), where G
N
DS21810D-page 11
L
values for differ-
= +2 V/V).
+ 15 mV (max.)
–
V DD
ISO
DD
N
V
/2 and
V
OUT
N
and the
OUT
is the
N
is