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參數(shù)資料
| 型號： | OP281GS |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 運動控制電子 |
| 英文描述： | Ultralow Power, Rail-to-Rail Output Operational Amplifiers |
| 中文描述： | DUAL OP-AMP, 2500 uV OFFSET-MAX, 0.105 MHz BAND WIDTH, PDSO8 |
| 封裝： | MS-012AA, SOIC-8 |
| 文件頁數(shù)： | 10/16頁 |
| 文件大?。?/td> | 963K |
| 代理商： | OP281GS |
REV. B
–10–
OP281/OP481
APPLICATIONS
Theory of Operation
The OPx81 family of op amps is comprised of extremely low
powered, rail-to-rail output amplifiers, requiring less than 4
m
A
of quiescent current per amplifier. Many other competitors
’
devices may be advertised as low supply current amplifiers but
draw significantly more current as the outputs of these devices
are driven to a supply rail. The OPx81
’
s supply current remains
under 4
m
A even with the output driven to either supply rail.
Supply currents should meet the specification as long as the
inputs and outputs remain within the range of the power supplies.
Figure 1 shows a simplified schematic of a single channel for the
OPx81. A bipolar differential pair is used in the input stage.
PNP transistors are used to allow the input stage to remain
linear with the common-mode range extending to ground. This
is an important consideration for single-supply applications. The
bipolar front end also contributes less noise than a MOS front
end with only nano-amps of bias currents. The output of the op
amp consists of a pair of CMOS transistors in a common source
configuration. This setup allows the output of the amplifier to
swing to within millivolts of either supply rail. The headroom
required by the output stage is limited by the amount of current
being driven into the load. The lower the output current, the
closer the output can go to either supply rail. TPCs 7, 8, and 9
show the output voltage headroom versus load current. This
behavior is typical of rail-to-rail output amplifiers.
+IN
–IN
V
EE
OUT
V
CC
Figure 1. Simplified Schematic of a Single OPx81 Channel
Input Overvoltage Protection
The input stage to the OPx81 family of op amps consists of a
PNP differential pair. If the base voltage of either of these input
transistors drops to more than 0.6 V below the negative supply,
the input ESD protection diodes will become forward biased,
and large currents will begin to flow. In addition to possibly
damaging the device, this will create a phase reversal effect at
the output. To prevent these effects from happening, the input
current should be limited to less than 0.5 mA.
This can be done quite easily by placing a resistor in series with
the input to the device. The size of the resistor should be pro-
portional to the lowest possible input signal excursion and can
be found using the following formula:
R
=
V
EE
-
V
IN
,
MIN
0.5
￥
10
-
3
where:
V
EE
is the negative power supply for the amplifier.
V
IN, MIN
is the lowest input voltage excursion expected.
For example, a single channel of the OPx81 is to be used with a
single-supply voltage of +5 V where the input signal could possibly
go as low as
–
1 V. Because the amplifier is powered from a single
supply, V
EE
is ground, so the necessary series resistance should
be 2 k
W
.
Input Offset Voltage
The OPx81 family of op amps was designed for low offset
voltages less than 1 mV.
OP281
V
OUT
+3V
100k
100k
100k
100k
V
IN
= 1kHz AT
400mV p-p
–0.1V
–0.27V
Figure 2. Single OPx81 Channel Configured as
a Difference Amplifier Operating at V
CM
< 0 V
Input Common-Mode Voltage Range
The OPx81 is rated with an input common-mode voltage range
from V
EE
to 1 V under V
CC
. However, the op amp can still oper-
ate even with a common-mode voltage that is slightly
less
than V
EE
.
Figure 2 shows a single OPx81 channel configured as a difference
amplifier with a single-supply voltage of 3 V. Negative dc voltages
are applied at both input terminals creating a common-mode volt-
age that is less than ground. A 400 mV p-p input signal is then
applied to the noninverting input. Figure 3 shows the input and
output waves. Notice how the output of the amplifier also drops
slightly
negative
without distortion.
10
0%
100
90
0.2ms
0.1V
0V
V
IN
V
OUT
Figure 3. Input and Output Signals with V
CM
< 0 V
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| OP481 | Ultralow Power, Rail-to-Rail Output Operational Amplifiers |
| OP481GRU | Ultralow Power, Rail-to-Rail Output Operational Amplifiers |
| OP481GS | Ultralow Power, Rail-to-Rail Output Operational Amplifiers |
| OP481GP | Ultralow Power, Rail-to-Rail Output Operational Amplifiers |
| OP281GP | Ultralow Power, Rail-to-Rail Output Operational Amplifiers |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OP281GS-REEL | 制造商:Analog Devices 功能描述:OP Amp Dual GP R-R O/P |
| OP281GS-REEL7 | 制造商:Analog Devices 功能描述:OP Amp Dual GP R-R O/P |
| OP281GSZ | 功能描述:IC OPAMP GP R-R 105KHZ LP 8SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:2,500 系列:- 放大器類型:通用 電路數(shù):4 輸出類型:- 轉(zhuǎn)換速率:0.6 V/µs 增益帶寬積:1MHz -3db帶寬:- 電流 - 輸入偏壓:45nA 電壓 - 輸入偏移:2000µV 電流 - 電源:1.4mA 電流 - 輸出 / 通道:40mA 電壓 - 電源，單路/雙路(±):3 V ~ 32 V，±1.5 V ~ 16 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:14-TSSOP（0.173"，4.40mm 寬） 供應商設(shè)備封裝:14-TSSOP 包裝:帶卷 (TR) 其它名稱:LM324ADTBR2G-NDLM324ADTBR2GOSTR |
| OP281GSZ-REEL | 功能描述:IC OPAMP GP R-R 105KHZ LP 8SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:100 系列:- 放大器類型:通用 電路數(shù):1 輸出類型:- 轉(zhuǎn)換速率:0.2 V/µs 增益帶寬積:- -3db帶寬:- 電流 - 輸入偏壓:100pA 電壓 - 輸入偏移:30µV 電流 - 電源:380µA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):±2 V ~ 18 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應商設(shè)備封裝:8-SO 包裝:管件 |
| OP281GSZ-REEL7 | 功能描述:IC OPAMP GP R-R 105KHZ LP 8SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:100 系列:- 放大器類型:通用 電路數(shù):1 輸出類型:- 轉(zhuǎn)換速率:0.2 V/µs 增益帶寬積:- -3db帶寬:- 電流 - 輸入偏壓:100pA 電壓 - 輸入偏移:30µV 電流 - 電源:380µA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):±2 V ~ 18 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應商設(shè)備封裝:8-SO 包裝:管件 |
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