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參數(shù)資料
| 型號： | OP493 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Precision, Micropower Operational Amplifiers(精密的微功率四運放) |
| 中文描述： | 精密，微功耗運算放大器（精密的微功率四運放） |
| 文件頁數(shù)： | 13/16頁 |
| 文件大?。?/td> | 273K |
| 代理商： | OP493 |
OP193/OP293/OP493
REV. A
–13–
From the formulas, it can be seen that if the span trim is ad-
justed before the zero trim, the two trims are not interactive,
which greatly simplifies the calibration procedure.
Calibration of the transmitter is simple. First, the slope of the
output current versus temperature is calibrated by adjusting the
span trim, R7. A couple of iterations may be required to be sure
the slope is correct.
Once the span trim has been completed, the zero trim can be
made. Remember that adjusting the zero trim will not affect the
gain.
T he zero trim can be set at any known temperature by adjusting
R5 until the output current equals:
I
OUT
=
I
FS
T
OPERATING
(
T
AMBIENT
T
MIN
)
+
4
mA
T able I shows the values of R6 required for various temperature
ranges.
T able I. R6 Values vs. T emperature
T emp Range
R6
0
°
C to +70
°
C
–40
°
C to +85
°
C
–55
°
C to +150
°
C
10 k
6.2 k
3 k
A Micropower Voltage Controlled Oscillator
An OP293 in combination with an inexpensive quad CMOS
analog switch forms the precision VCO of Figure 34. T his cir-
cuit provides triangle and square wave outputs and draws only
50
μ
A from a single 5 V supply. A1 acts as an integrator; S1
switches the charging current symmetrically to yield positive and
negative ramps. T he integrator is bounded by A2 which acts as
a Schmitt trigger with a precise hysteresis of 1.67 volts, set by
resistors R5, R6, and R7, and associated CMOS switches. T he
resulting output of A1 is a triangle wave with upper and lower
levels of 3.33 and 1.67 volts. T he output of A2 is a square wave
with almost rail-to-rail swing. With the components shown, fre-
quency of operation is given by the equation:
f
OUT
=
V
CONTROL
(
Volts
)
×
10
Hz/V
but this can easily be changed by varying C1. T he circuit oper-
ates well up to 500 Hz.
8
4
1/2 OP293
1
2
3
R3
100k
V
CONTROL
R4
200k
TRIANGLE
OUT
A1
+5V
R1
200k
R2
200k
1/2 OP293
6
5
7
A2
SQUARE
OUT
+5V
R6
200k
R7
200k
S3
S4
S1
1 IN/OUT
2 OUT/IN
CONT 12
OUT/IN 10
3 OUT/IN
S2
CONT 13
4 IN/OUT
6 CONT
5 CONT
7
V
SS
IN/OUT 8
IN/OUT 11
OUT/IN 9
V
DD
14
+5V
+5V
CD4066
R8
200k
+5V
R5
200k
C1
75nF
Figure 34. Micropower Voltage Controlled Oscillator
A Micropower, Single-Supply Quad Voltage Output 8-Bit
DAC
T he circuit of Figure 35 uses the DAC8408 CMOS quad 8-bit
DAC and the OP493 to form a single-supply quad voltage out-
put DAC with a supply drain of only 140
μ
A. T he DAC8408 is
used in the voltage switching mode and each DAC has an out-
put resistance (
≈
10 k
) independent of the digital input code.
T he output amplifiers act as buffers to avoid loading the DACs.
T he 100 k
resistors ensure that the OP493 outputs will swing
to within 1/2 LSB of ground, i.e.:
1
2
×
1.23
V
256
=
3
mV
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| OP497GS | Precision Picoampere Input Current Quad Operational Amplifier |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OP4930003SR | 制造商:Analog Devices 功能描述: |
| OP493EP | 制造商:Rochester Electronics LLC 功能描述:MICROPOWER RAIL/RAIL - Bulk |
| OP493ES | 制造商:AD 制造商全稱:Analog Devices 功能描述:Precision, Micropower Operational Amplifiers |
| OP493ES-REEL | 制造商:AD 制造商全稱:Analog Devices 功能描述:Precision, Micropower Operational Amplifiers |
| OP493FP | 制造商:Rochester Electronics LLC 功能描述:MICROPOWER RAIL/RAIL - Bulk 制造商:Analog Devices 功能描述: |
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