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參數(shù)資料
| 型號： | OP281GP |
| 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, PDIP8 |
| 封裝： | PLASTIC, DIP-8 |
| 文件頁數(shù)： | 11/16頁 |
| 文件大小： | 963K |
| 代理商： | OP281GP |
REV. B
OP281/OP481
–11–
Capacitive Loading
Most low supply current amplifiers have difficulty driving
capacitive loads due to the higher currents required from the
output stage for such loads. Higher capacitance at the output
will increase the amount of overshoot and ringing in the amplifier
’
s
step response and could even affect the stability of the device.
However, through careful design of the output stage and its
high phase margin, the OPx81 family can tolerate some degree of
capacitive loading. Figure 4 shows the step response of a single
channel with a 10 nF capacitor connected at the output. Notice
that the overshoot of the output does not exceed more than 10%
with such a load, even with a supply voltage of only 3 V.
10
0%
100
90
Figure 4. Ringing and Overshoot of the Output
of the Amplifier
Micropower Reference Voltage Generator
Many single-supply circuits are configured with the circuit biased
to 1/2 of the supply voltage. In these cases, a false ground refer-
ence can be created by using a voltage divider buffered by an
amplifier. Figure 5 shows the schematic for such a circuit.
The two 1 M
W
resistors generate the reference voltage while
drawing only 1.5
m
A of current from a 3 V supply. A capacitor
connected from the inverting terminal to the output of the op amp
provides compensation to allow for a bypass capacitor to be
connected at the reference output. This bypass capacitor helps
to establish an ac ground for the reference output. The entire
reference generator draws less than 5
m
A from a 3 V supply source.
1
8
4
2
3
OP281
10k
0.022 F
V
REF
1.5V TO 6V
1 F
1 F
1M
3V TO 12V
100
1M
Figure 5. Single Channel Configured as a Micropower
Bias Voltage Generator
Window Comparator
The extremely low power supply current demands of the OPx81
family make it ideal for use in long-life battery-powered applica-
tions such as a monitoring system. Figure 6 shows a circuit that
uses the OP281 as a window comparator.
A1
R1
R2
3V
OP281-A
V
IN
2k
5.1k
3V
3V
V
OUT
Q1
5.1k
V
H
D1
10k
A2
R3
R4
3V
3V
V
L
D2
OP281-B
Figure 6. Using the OP281 as a Window Comparator
The threshold limits for the window are set by V
H
and V
L
, pro-
vided that V
H
> V
L
. The output of A1 will stay at the negative
rail, in this case ground, as long as the input voltage is less than
V
H
. Similarly, the output of A2 will stay at ground as long the
input voltage is higher than V
L
. As long as V
IN
remains between
V
L
and V
H
, the outputs of both op amps will be 0 V. With no
current flowing in either D1 or D2, the base of Q1 will stay at
ground, putting the transistor in cutoff and forcing V
OUT
to the
positive supply rail. If the input voltage rises above V
H
, the
output of A2 stays at ground, but the output of A1 will go to the
positive rail, and D1 will conduct current. This creates a base
voltage that will turn on Q1 and drive V
OUT
low. The same
condition occurs if V
IN
falls below V
L
with A2
’
s output going
high, and D2 conducting current. Therefore, V
OUT
will be high
if the input voltage is between V
L
and V
H
, and V
OUT
will be low
if the input voltage moves outside of that range.
The R1 and R2 voltage divider sets the upper window voltage,
and the R3 and R4 voltage divider sets the lower voltage for the
window. For the window comparator to function properly, V
H
must be a greater voltage than V
L
.
V
H
=
R
2
R
1
+
R
2
R
4
R
3
+
R
4
V
L
=
The 2 k
W
resistor connects the input voltage to the input terminals
to the op amps. This protects the OP281 from possible excess
current flowing into the input stages of the devices. D1 and D2 are
small-signal switching diodes (1N4446 or equivalent), and Q1
is a 2N2222 or equivalent NPN transistor.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| OP281GRU | 制造商:AD 制造商全稱:Analog Devices 功能描述:Ultralow Power, Rail-to-Rail Output Operational Amplifiers |
| OP281GRU-REEL | 制造商:Rochester Electronics LLC 功能描述:DUAL 5UA RAIL TO RAIL OP AMP - Tape and Reel 制造商:Analog Devices 功能描述: |
| OP281GRUZ-REEL | 功能描述:IC OPAMP GP R-R 105KHZ LP 8TSSOP RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:1 系列:- 放大器類型:電流檢測 電路數(shù):1 輸出類型:- 轉換速率:- 增益帶寬積:125kHz -3db帶寬:- 電流 - 輸入偏壓:- 電壓 - 輸入偏移:100µV 電流 - 電源:1.1µA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):- 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:4-WFBGA，CSPBGA 供應商設備封裝:4-UCSP（2x2） 包裝:剪切帶 (CT) 其它名稱:MAX9634WERS+TCT |
| OP281GS | 制造商:Analog Devices 功能描述:OP Amp Dual GP R-R O/P 制造商:Rochester Electronics LLC 功能描述:DUAL 5UA RAIL TO RAIL OP AMP - Bulk 制造商:Analog Devices 功能描述:IC OP-AMP DUAL ULOW-PWR RRO/P |
| OP281GS-REEL | 制造商:Analog Devices 功能描述:OP Amp Dual GP R-R O/P |
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