MCP6L91 Microchip Technology Inc., MCP6L91 Datasheet - Page 11

• Manufacturer Part Number: MCP6L91
• Description: 10 Mhz, 850 ?a Op Amps
• Manufacturer: Microchip Technology Inc.

4.0
The MCP6L91/1R/2/4 family of op amps is manufac-
tured using Microchip’s state of the art CMOS process.
It is designed for low cost, low power and general pur-
pose applications. The low supply voltage, low
quiescent current and wide bandwidth makes the
MCP6L91/1R/2/4 ideal for battery-powered applica-
tions.
4.1
4.1.1
The MCP6L91/1R/2/4 op amps are designed to
prevent phase inversion when the input pins exceed
the supply voltages.
voltage exceeding both supplies without any phase
reversal.
4.1.2
In order to prevent damage and/or improper operation
of these amplifiers, the circuit they are in must limit the
currents (and voltages) at the input pins (see
Section 1.1
Figure 4-1
protecting these inputs. The internal ESD diodes
prevent the input pins (V
far below ground, and the resistors R
possible current drawn out of the input pins. Diodes D
and D
going too far above V
V
FIGURE 4-1:
Inputs.
© 2009 Microchip Technology Inc.
DD
.
2
V
V
prevent the input pins (V
APPLICATION INFORMATION
Rail-to-Rail Inputs
1
2
R
R
1
2
PHASE REVERSAL
INPUT VOLTAGE AND CURRENT
LIMITS
shows the recommended approach to
>
>
R
R
“Absolute
V
V
1
2
SS
SS
D
1
– (minimum expected V
– (minimum expected V
DD
Protecting the Analog
D
Figure 2-10
2
, and dump any currents onto
IN
+ and V
2 mA
2 mA
Maximum
MCP6L9X
R
V
IN
IN
3
DD
+ and V
–) from going too
shows an input
1
and R
Ratings †”).
1
2
)
)
2
IN
limit the
–) from
1
A significant amount of current can flow out of the
inputs (through the ESD diodes) when the common
mode voltage (V
Figure
need to limit the usable voltage range.
4.1.3
The input stage of the MCP6L91/1R/2/4 op amps use
two differential CMOS input stages in parallel. One
operates at low common mode input voltage (V
while the other operates at high V
topology, and at room temperature, the device
operates with V
below V
The transition between the two input stages occurs
when V
gain linearity, with non-inverting gains, avoid this region
of operation.
4.2
The output voltage range of the MCP6L91/1R/2/4 op
amps is V
(maximum) when R
and V
tion.
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., > 100 pF when G = +1), a small series
resistor at the output (R
feedback loop’s stability by making the output load
resistive at higher frequencies; the bandwidth will
usually be decreased.
FIGURE 4-2:
stabilizes large capacitive loads.
Bench measurements are helpful in choosing R
Adjust R
Figure
DD
2-7. Applications that are high impedance may
R
2-14) has reasonable overshoot (e.g., 4%).
R
SS
CM
ISO
G
= 5.0V. Refer to
N
Rail-to-Rail Output
Capacitive Loads
(typical at 25°C).
DD
= V
MCP6L91/1R/2/4
NORMAL OPERATION
so that a small signal step response (see
– 20 mV (minimum) and V
DD
MCP6L9X
CM
– 1.1V. For the best distortion and
CM
up to 0.3V above V
L
R
) is below ground (V
= 10 kΩ is connected to V
F
Output Resistor, R
ISO
Figure 2-13
in
Figure
R
C
ISO
L
DS22141A-page 11
4-2) improves the
for more informa-
CM
DD
. WIth this
SS
ISO
and 0.3V
SS
V
+ 20 mV
OUT
); see
DD
CM
ISO
/2
),
.