参数资料
| 型号： | OP492GSZ-REEL |
| 厂商： | Analog Devices Inc |
| 文件页数： | 7/20页 |
| 文件大小： | 0K |
| 描述： | IC OPAMP GP 4MHZ QUAD 14SOIC |
| 标准包装： | 2,500 |
| 放大器类型： | 通用 |
| 电路数： | 4 |
| 转换速率： | 4 V/µs |
| 增益带宽积： | 4MHz |
| 电流 - 输入偏压： | 375nA |
| 电压 - 输入偏移： | 1400µV |
| 电流 - 电源： | 1mA |
| 电流 - 输出 / 通道： | 10.5mA |
| 电压 - 电源，单路/双路(±)： | 4.5 V ~ 33 V，±2.25 V ~ 16.5 V |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 14-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 14-SOIC |
| 包装： | 带卷 (TR) |
OP292/OP492
Rev. C | Page 15 of 20
50 Hz/60 Hz SINGLE-SUPPLY NOTCH FILTER
Figure 39 shows a notch filter that achieves nearly 30 dB of
60 Hz rejection while powered by only a single 12 V supply.
The circuit also works well on 5 V systems. The filter uses a
twin-T configuration, whose frequency selectivity depends
heavily on the relative matching of the capacitors and resistors in
the twin-T section. Mylar is a good choice for the capacitors of
the twin-T, and the relative matching of the capacitors and resistors
determines the pass-band symmetry of the filter. Using 1%
resistors and 5% capacitors produces satisfactory results.
The amount of rejection and the Q of the filter is solely determined
by one resistor and is shown in the table with Figure 39. The
bottom amplifier is used to split the supply to bias the amplifier
to midlevel. The circuit can be modified to reject 50 Hz by simply
changing the resistors in the twin-T section (Rl through R4)
from 2.67 kΩ to 3.16 kΩ and by changing R5 to of 3.16 kΩ. For
best results, the common value resistors can be from a resistor
array for optimum matching characteristics.
1/4
OP492
C1
1F
C3
2F
(1F × 2)
R5
1.335k
(2.67k ÷ 2)
R4
2.67k
C2
1F
R6
100k
8k
12V
R8
100k
R9
100k
C4
1F
6V
R7
1k
VIN
VOUT
NOTES
1. FOR 50Hz APPLICATION CHANGE R12 TO R4 TO 3.16k
AND R5 TO 1.58k (3.16k ÷ 2)
FILTER Q
0.75
1.00
1.25
2.50
5.00
10.00
RQ (k)
1.0
2.0
3.0
8.0
18
38
REJECTION (dB)
40
35
30
25
20
15
VOLTAGE GAIN
1.33
1.50
1.60
1.80
1.90
1.95
1/4
OP492
1/4
OP492
R3
2.67k
R1
2.67k
RQ
+
00
31
0-
0
39
R2
2.67k
Figure 39. Single-Supply 50 Hz/60 Hz Notch Filter
FOUR-POLE BESSEL LOW-PASS FILTER
The linear phase filter in Figure 40 is designed to roll off at a
voice-band cutoff frequency of 3.6 kHz. The four poles are
formed by two cascading stages of 2-pole Sallen-Key filters.
5V
5k
1.78k 16.2k
100F
2
3
1
8
4
6
5
7
5V
VIN
VOUT
1.1k 14.3k
0.01F
0.022F
3300pF
2200pF
1/2
OP292
1/2
OP292
00
31
0-
04
0
Figure 40. Four-Pole Bessel Low-Pass Filter Using Sallen-Key Topology
LOW COST, LINEARIZED THERMISTOR AMPLIFIER
An inexpensive thermometer amplifier circuit can be implemented
using low cost thermistors. One such implementation is shown
in Figure 41. The circuit measures temperature over the range
of 0°C to 70°C to an accuracy of ±0.3°C as the linearization
circuit works well within a narrow temperature range. However, it
can measure higher temperatures but at a slightly reduced accuracy.
To achieve the aforementioned accuracy, the nonlinearity of the
thermistor must be corrected. This is done by connecting the
thermistor in parallel with the 10 kΩ in the feedback loop of the
first stage amplifier. A constant operating current of 281 μA is
supplied by the resistor R1 with the 5 V reference from the
REF195 such that the self-heating error of the thermistor is
kept below 0.1°C.
In many cases, the thermistor is placed some distance from the
signal conditioning circuit. Under this condition, a 0.1 μF capacitor
placed across R2 will help to suppress noise pickup.
This linearization network creates an offset voltage that is corrected
by summing a compensating current with Potentiometer P1.
The temperature dependent signal is amplified by the second
stage, producing a transfer coefficient of 10 mV/°C at the output.
To calibrate, a precision decade box can be used in place of the
thermistor. For 0°C trim, the decade box is set to 32.650 kΩ,
and P1 is adjusted until the output of the circuit reads 0 V. To
trim the circuit at the full-scale temperature of 70°C, the decade
box is then set to 1.752 kΩ, and P2 is adjusted until the circuit
reads 0.70 V.
REF195
15V
5V
1F
R12
17.8k
R12
17.8k
RT1
10k NTC
R5
806k
R4
41.2k
R3
10k
R6
7.87k
P2
200
70°C TRIM
VOUT
–10mV/°C
NOTES
1. ALL RESISTORS ARE 1%, 25ppm/°C EXCEPT R5 = 1%, 100ppm/°C.
1RT = ALPHATHERMISTOR 13A1002-C3.
2R1 = 0.1% IMPERIAL ASTRONICS M015.
P1
10k
0°C TRIM
1.0F
1/2
OP292
1/2
OP292
00
31
0-
04
1
Figure 41. Low Cost Linearized Thermistor Amplifier
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