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參數(shù)資料
| 型號： | OP281GS |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 運(yùn)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)： | 12/16頁 |
| 文件大?。?/td> | 963K |
| 代理商： | OP281GS |
REV. B
–12–
OP281/OP481
Low-Side Current Monitor
In the design of power supply control circuits, a great deal of
design effort is focused on ensuring a pass transistor
’
s long-term
reliability over a wide range of load current conditions. As a
result, monitoring and limiting device power dissipation is of
prime importance in these designs. Figure 7 shows an example
of a 5 V, single-supply current monitor that can be incorporated
into the design of a voltage regulator with fold-back current
limiting or a high current power supply with crowbar protection.
The design capitalizes on the OPx81
’
s common-mode range
that extends to ground. Current is monitored in the power sup-
ply return path where a 0.1
W
shunt resistor, R
SENSE
, creates a
very small voltage drop. The voltage at the inverting terminal
becomes equal to the voltage at the noninverting terminal through
the feedback of Q1, which is a 2N2222 or equivalent NPN tran-
sistor. This makes the voltage drop across R1 equal to the voltage
drop across R
SENSE
. Therefore, the current through Q1 becomes
directly proportional to the current through R
SENSE
, and the output
voltage is given by:
R
2
R
1
￥
R
SENSE
￥
I
L
The voltage drop across
R2
increases with
I
L
increasing, so
V
OUT
decreases with higher supply current being sensed. For the
element values shown, the
V
OUT
transfer characteristic is
–
2.5 V/A,
decreasing from
V
EE
.
V
OUT
=
V
EE
-
ê
ˉ
5V
RETURN TO
GROUND
5V
R2
2.49k
V
OUT
R1
100
0.1
R
SENSE
Q1
SINGLE
CHANNEL
OPx81
Figure 7. Low-Side Load Current Monitor
Low Voltage Half-Wave and Full-Wave Rectifiers
Because of its quick overdrive recovery time, an OP281 can be
configured as a full-wave rectifier for low frequency (<500 Hz)
applications. Figure 8 shows the schematic.
3V
OP281-A
V
IN
= 2V p-p
2k
A1
3V
OP281-B
A2
R1 = 100k
R2 = 100k
FULL-WAVE
RECTIFIED
OUTPUT
HALF-WAVE
RECTIFIED
OUTPUT
Figure 8. Single-Supply Full-Wave and Half-Wave
Rectifiers Using an OP281
10
0%
100
90
SCALE 0.1V/DIV
SCALE 0.1ms/DIV
Figure 9. Full-Wave Rectified Signal
Amplifier A1 is used as a voltage follower that will track the input
voltage only when it is greater than 0 V. This provides a half-wave
rectification of the input signal to the noninverting terminal of
amplifier A2. When A1
’
s output is following the input, the invert-
ing terminal of A2 will also follow the input from the virtual
ground between the inverting and noninverting terminals of A2.
With no potential difference across R1, no current flows through
either R1 or R2, therefore the output of A2 will also follow the input.
Now, when the input voltage goes below 0 V, the noninverting
terminal of A2 becomes 0 V. This makes A2 work as an inverting
amplifier with a gain of 1 and provides a full-wave rectified version
of the input signal. A 2 k
W
resistor in series with A1
’
s noninverting
input protects the device when the input signal becomes less
than ground.
Battery-Powered Telephone Headset Amplifier
Figure 10 shows how the OP281 can be used as a two-way
amplifier in a telephone headset. One side of the OP281 can be
used as an amplifier for the microphone, while the other side can
be used to drive the speaker. A typical telephone headset uses a
600
W
speaker and an electret microphone that requires a supply
voltage and a biasing resistor.
3V
OP281-B
20k
20k
Q1
Q2
3V
1 F
600
SPEAKER
50k
10k
1 F
10k
POT.
3V
1M
1M
1 F
1 F
INPUT
1M
3V
OP281-A
11k
300k
0.1 F
1 F
3V
1M
1 F
MIC OUT
2.2k
3V
ELECTRET
MIC
Figure 10. Two-Way Amplifier in a Battery-Powered
Telephone Headset
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(biāo)準(zhǔn)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(yīng)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(biāo)準(zhǔn)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(yīng)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(biāo)準(zhǔn)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(yīng)商設(shè)備封裝:8-SO 包裝:管件 |
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