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參數(shù)資料
| 型號(hào)： | OP295 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | DUAL/QUAD RAIL-TO-RAIL OPERATIONAL AMPLIFIERS |
| 中文描述： | 雙/四軌至軌運(yùn)算放大器 |
| 文件頁(yè)數(shù)： | 9/12頁(yè) |
| 文件大?。?/td> | 328K |
| 代理商： | OP295 |
OP295/OP495
REV. B
–9–
common-mode rejection performance and minimize drift. T his
instrumentation amplifier can operate from a supply voltage as
low as 3 volts.
A Single Supply RT D T hermometer Amplifier
T his RT D amplifier takes advantage of the rail-to-rail swing of
the OP295/OP495 to achieve a high bridge voltage in spite of a
low 5 V supply. T he OP295/OP495 amplifier servos a constant
200
μ
A current to the bridge. T he return current drops across
the parallel resistors 6.19 k
and the 2.55 M
, developing a
voltage that is servoed to 1.235 V, which is established by the
AD589 bandgap reference. T he 3-wire RT D provides an equal
line resistance drop in both 100
legs of the bridge, thus im-
proving the accuracy.
T he AMP04 amplifies the differential bridge signal and converts
it to a single-ended output. T he gain is set by the series resis-
tance of the 332
resistor plus the 50
potentiometer. T he
gain scales the output to produce a 4.5 V full scale. T he
0.22
μ
F capacitor to the output provides a 7 Hz low-pass filter
to keep noise at a minimum.
3
7
1
8
6
5
4
2
AMP04
0.22
μ
F
332
50
26.7k
0.5%
100
0.5%
100
RTD
2.55M
1%
6.19k
1%
AD589
1.235
37.4k
+5V
200
10-TURNS
ZERO ADJ
26.7k
0.5%
V
O
4.5V = 450
°
C
0V = 0
°
C
+5V
1
2
3
1/2
OP295/
OP495
Figure 6. Low Power RTD Amplifier
A Cold Junction Compensated, Battery Powered
T hermocouple Amplifier
T he OP295/OP495’s 150
μ
A quiescent current per amplifier
consumption makes it useful for battery powered temperature
measuring instruments. T he K -type thermocouple terminates
into an isothermal block where the terminated junctions’ ambi-
ent temperatures can be continuously monitored and corrected
by summing an equal but opposite thermal EMF to the ampli-
fier, thereby canceling the error introduced by the cold junctions.
V
O
0V = 0
°
C
5V = 500
°
C
4.99k
1%
1.33M
20k
SCALE
ADJUST
9V
24.3k
1%
24.9k
7.15k
1%
1.235V
AD589
24.9k
1%
500
10-TURN
2.1k
1%
475
1%
1.5M
1%
1N914
ISOTHERMAL
BLOCK
COLD
JUNCTIONS
CR
AL
CHROMEL
K-TYPE
THERMOCOUPLE
40.7
μ
V/
°
C
ZERO
ADJUST
8
1
4
2
3
ALUMEL
OP295/
OP495
Figure 7. Battery Powered, Cold-J unction Compensated
Thermocouple Amplifier
T o calibrate, immerse the thermocouple measuring junction in a
0
°
C ice bath, adjust the 500
Zero Adjust pot to zero volts out.
T hen immerse the thermocouple in a 250
°
C temperature bath
or oven and adjust the Scale Adjust pot for an output voltage of
2.50 V, which is equivalent to 250
°
C. Within this temperature
range, the K -type thermocouple is quite accurate and produces
a fairly linear transfer characteristic. Accuracy of
±
3
°
C is achiev-
able without linearization.
Even if the battery voltage is allowed to decay to as low as 7 volts,
the rail-to-rail swing allows temperature measurements to
700
°
C. However, linearization may be necessary for tempera-
tures above 250
°
C where the thermocouple becomes rather
nonlinear. T he circuit draws just under 500
μ
A supply current
from a 9 V battery.
A 5 V Only, 12-Bit DAC T hat Swings 0 V to 4.095 V
Figure 8 shows a complete voltage output DAC with wide out-
put voltage swing operating off a single +5 V supply. T he serial
input 12-bit D/A converter is configured as a voltage output
device with the 1.235 V reference feeding the current output pin
(I
OUT
) of the DAC. T he V
REF
which is normally the input now
becomes the output.
T he output voltage from the DAC is the binary weighted volt-
age of the reference, which is gained up by the output amplifier
such that the DAC has a 1 mV per bit transfer function.
+5V
R2
41.2k
R3
5k
R4
100k
V
DD
R
FB
V
REF
SRI
CLK
GND
I
OUT
DAC8043
3
4
7
6
5
1
2
8
+5V
DIGITAL
CONTROL
+5V
AD589
R1
17.8k
+1.23V
LD
V
O
=
1
(4.096V)
D
4096
TOTAL POWER DISSIPATION = 1.6mW
8
4
2
3
OP295/
OP495
Figure 8. A 5 Volt 12-Bit DAC with 0 V to +4.095 Output
Swing
4–20 mA Current Loop T ransmitter
Figure 9 shows a self powered 4–20 mA current loop transmit-
ter. T he entire circuit floats up from the single supply (12 V to
36 V) return. T he supply current carries the signal within the 4
to 20 mA range. T hus the 4 mA establishes the baseline
8
1
2
3
220pF
220
REF02
GND
6
2
4
100
2N1711
100k
1%
HP
5082-2800
100
1%
V
0 + 3V
100k
10-TURN
1.21M
1%
NULL ADJ
SPAN ADJ
182k
1%
10k
10-TURN
5V
+12V
TO
+36V
R
L
100
4–20mA
4
1/2
OP295/
OP495
Figure 9. 4–20 mA Current Loop Transmitter
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| OP295GP | DUAL/QUAD RAIL-TO-RAIL OPERATIONAL AMPLIFIERS |
| OP495GP | DUAL/QUAD RAIL-TO-RAIL OPERATIONAL AMPLIFIERS |
| OP295GS | DUAL/QUAD RAIL-TO-RAIL OPERATIONAL AMPLIFIERS |
| OP495GS | DUAL/QUAD RAIL-TO-RAIL OPERATIONAL AMPLIFIERS |
| op295 | Rail to Rail Dual OP AMP(滿幅度雙運(yùn)算放大器) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OP295_06 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Dual/Quad Rail-to-Rail Operational Amplifiers |
| OP2950013P | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| OP295A | 功能描述:紅外發(fā)射源 Infrared 890nm RoHS:否 制造商:Fairchild Semiconductor 波長(zhǎng):880 nm 射束角:+/- 25 輻射強(qiáng)度: 最大工作溫度:+ 100 C 最小工作溫度:- 40 C 封裝 / 箱體:Side Looker 封裝:Bulk |
| OP295AZ/883 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Voltage-Feedback Operational Amplifier |
| OP295B | 功能描述:紅外發(fā)射源 Infrared 890nm RoHS:否 制造商:Fairchild Semiconductor 波長(zhǎng):880 nm 射束角:+/- 25 輻射強(qiáng)度: 最大工作溫度:+ 100 C 最小工作溫度:- 40 C 封裝 / 箱體:Side Looker 封裝:Bulk |
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