MCP6143T-I/SN Microchip Technology, MCP6143T-I/SN Datasheet - Page 17

• Manufacturer Part Number: MCP6143T-I/SN
• Description: IC OPAMP 1.4V SNGL W/CS RR 8SOIC
• Manufacturer: Microchip Technology

Specifications of MCP6143T-I/SN

• Amplifier Type: General Purpose
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• Slew Rate: 0.003 V/µs
• Gain Bandwidth Product: 100kHz
• Current - Input Bias: 1pA
• Voltage - Input Offset: 3000µV
• Current - Supply: 0.6µA
• Current - Output / Channel: 20mA
• Voltage - Supply, Single/dual (±): 1.4 V ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• -3db Bandwidth: -

Figure 4-5
unstable when used with the MCP6141/2/3/4 family.
The unity gain buffer and low gain amplifier
(non-inverting or inverting) are at gains that are too low
for stability (see
capacitor makes it reach unity gain at high frequencies,
causing instability.
FIGURE 4-5:
Circuits for the MCP6141/2/3/4 Family.
4.4.2
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.
© 2009 Microchip Technology Inc.
Note:
Unity Gain Buffer
Low Gain Amplifier
Miller Integrator
V
V
V
IN
1
2
The three circuits shown in
not to be used with the MCP6141/2/3/4 op
amps. They are included for illustrative
purposes only.
CAPACITIVE LOADS
shows three example circuits that are
V
IN
Equation
R
R
R
G
N
Examples of Unstable
MCP614X
MCP614X
MCP614X
4-2).The Miller integrator’s
R
C
F
1
+
------ -
R
Figure 4-5
R
F
G
<
V
OUT
10
V
V
OUT
OUT
are
When driving large capacitive loads with these op
amps (e.g., > 60 pF when G = +10), 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 4-6:
stabilizes large capacitive loads.
Figure 4-7
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., -9 V/V gives G
FIGURE 4-7:
for Capacitive Loads.
After selecting R
resulting frequency response peaking and step
response overshoot. Modify R
response is reasonable. Bench evaluation and
simulations with the MCP6141/2/3/4 SPICE macro
model are helpful.
4.5
The MCP6143 is a single op amp with Chip Select
(CS). When CS is pulled high, the supply current drops
to 50 nA (typical) and flows through the CS pin to V
When this happens, the amplifier output is put into a
high impedance state. By pulling CS low, the amplifier
is enabled. If the CS pin is left floating, the amplifier will
not operate properly.
voltage and supply current response to a CS pulse.
V
100,000
A
10,000
1,000
100k
10k
1k
1.E+00
1p
R
MCP6143 Chip Select
V
G
B
gives recommended R
Normalized Load Capacitance; C
MCP6141/2/3/4
ISO
MCP614X
1.E+01
for your circuit, double check the
10p
Output Resistor, R
Recommended R
R
ISO
Figure 1-1
F
in
Figure
L
G
G
G
ISO
/G
N
N
N
1.E+02
100p
= +10
= +20
≥ +50
N
R
’s value until the
shows the output
C
), where G
DS21668D-page 17
4-6) improves the
ISO
N
L
ISO
= +10 V/V).
L
/G
ISO
values for
N
ISO
(F)
N
Values
1.E+03
and the
N
V
1n
OUT
is the
N
SS
is
.