參數(shù)資料
型號： MCP6271R
廠商： Microchip Technology Inc.
英文描述： 170 レA, 2 MHz Rail-to-Rail Op Amp
中文描述： 170レ甲，2 MHz的軌到軌運(yùn)算放大器
文件頁數(shù)： 13/34頁
文件大?。?/td> 1118K
代理商： MCP6271R
2006 Microchip Technology Inc.
DS21810E-page 13
MCP6271/1R/2/3/4/5
4.3
Capacitive Loads
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
ISO
in
Figure 4-3
) improves the
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.
Output Resistor, R
ISO
Figure 4-4
gives recommended R
ISO
values for
different capacitive loads and gains. The x-axis is the
normalized load capacitance (C
L
/G
N
), where G
N
is the
circuit's noise gain. For non-inverting gains, G
N
and the
Signal Gain are equal. For inverting gains, G
N
is
1+|Signal Gain| (e.g., –1 V/V gives G
N
= +2 V/V).
FIGURE 4-4:
for Capacitive Loads.
Recommended R
ISO
Values
After selecting R
ISO
for your circuit, double check the
resulting frequency response peaking and step
response overshoot. Modify R
ISO
's value until the
response is reasonable. Bench evaluation and
simulations with the MCP6271/1R/2/3/4/5 SPICE
macro model are helpful.
4.4
MCP6273/5 Chip Select (CS)
The MCP6273 and MCP6275 are single and dual op
amps with Chip Select (CS), respectively. When CS is
pulled high, the supply current drops to 0.7 μA (typ.)
and flows through the CS pin to V
SS
. When this
happens, the amplifier output is put into a high
impedance state. By pulling CS low, the amplifier is
enabled. The CS pin has a 5 M
Ω
(typ.) pull-down
resistor connected to V
SS
, so it will go low if the CS pin
is left floating.
Figure 1-1
shows the output voltage and
supply current response to a CS pulse.
4.5
Cascaded Dual Op Amps
(MCP6275)
The MCP6275 is a dual op amp with Chip Select (CS).
The Chip Select input is available on what would be the
non-inverting input of a standard dual op amp (pin 5).
This pin is available because the output of op amp A
connects to the non-inverting input of op amp B, as
shown in
Figure 4-5
. The Chip Select input, which can
be connected to a microcontroller I/O line, puts the
device in low power mode. Refer to
Section 4.4
“MCP6273/5 Chip Select (CS)”
.
FIGURE 4-5:
Cascaded Gain Amplifier.
The output of op amp A is loaded by the input
impedance of op amp B, which is typically
10
13
Ω
6 pF, as specified in the DC specification table
(Refer to
Section 4.3 “Capacitive Loads”
for further
details regarding capacitive loads).
The common mode input range of these op amps is
specified in the data sheet as V
SS
– 300 mV and
V
DD
+ 300 mV. However, since the output of op amp A
is limited to V
OL
and V
OH
(20 mV from the rails with a
10 k
Ω
load), the non-inverting input range of op amp B
is limited to the common mode input range of
V
SS
+ 20 mV and V
DD
– 20 mV.
V
IN
R
ISO
V
OUT
C
L
–
+
MCP627X
10
100
1,000
10
100
1,000
10,000
Normalized Load Capacitance; C
L
/ G
N
(pF)
R
I
:
)
G
N
= 1 V/V
G
N
= 2 V/V
G
N
t
4 V/V
A
B
CS
2
3
5
6
7
V
INA
+
V
OUTB
MCP6275
1
V
INA
–
V
OUTA
/V
INB
+
V
INB
–
相關(guān)PDF資料
PDF描述
MCP6271 300000 SYSTEM GATE 1.8 VOLT FPGA - NOT RECOMMENDED for NEW DESIGN
MCP6273 300000 SYSTEM GATE 1.8 VOLT FPGA - NOT RECOMMENDED for NEW DESIGN
MCP6274 300,000 SYSTEM GATE 1.8 VOLT FPGA - NOT RECOMMENDED for NEW DESIGN
MCP6275 170 UA, 2 MHz Rail-to-Rail Op Amp
MCP6291 1.0 mA, 10 MHz Rail-to-Rail Op Amp
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MCP6271RT-E/OT 功能描述:運(yùn)算放大器 - 運(yùn)放 Single 2 MHz OP E temp rvs pinout RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel
MCP6271T-E/MS 功能描述:運(yùn)算放大器 - 運(yùn)放 Single 2MHz RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel
MCP6271T-E/OT 功能描述:運(yùn)算放大器 - 運(yùn)放 Single 2 MHz OP E temp RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel
MCP6271T-E/SN 功能描述:運(yùn)算放大器 - 運(yùn)放 Single 2MHz RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel
MCP6272-E/MS 功能描述:運(yùn)算放大器 - 運(yùn)放 Dual 2MHz RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel
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