参数资料
| 型号： | OP279GSZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 3/16页 |
| 文件大小： | 0K |
| 描述： | IC OPAMP GP R-R 5MHZ DUAL 8SOIC |
| 标准包装： | 98 |
| 放大器类型： | 通用 |
| 电路数： | 2 |
| 输出类型： | 满摆幅 |
| 转换速率： | 3 V/µs |
| 增益带宽积： | 5MHz |
| 电流 - 输入偏压： | 300nA |
| 电压 - 输入偏移： | 4000µV |
| 电流 - 电源： | 3.75mA |
| 电流 - 输出 / 通道： | 50mA |
| 电压 - 电源，单路/双路(±)： | 4.5 V ~ 12 V，±2.25 V ~ 6 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOIC |
| 包装： | 管件 |
| 产品目录页面： | 768 (CN2011-ZH PDF) |
OP179/OP279
–11–
REV. G
UNITY-GAIN, SALLEN-KEY (VCVS) FILTERS
High Pass Configurations
Figure 14a is the HP form of a unity-gain 2-pole SK filter
using an OP179/OP279 section. For this filter and its LP coun-
terpart, the gain in the passband is inherently unity, and the
signal phase is noninverting due to the follower hookup. For
simplicity and practicality, capacitors C1-C2 are set equal, and
resistors R2-R1 are adjusted to a ratio “N,” which provides the
filter damping “
α” as per the design expressions. An HP design
starts with the selection of standard capacitor values for C1 and
C2, and a calculation of N. R1 and R2 are then calculated as
per the figure expressions.
In these examples,
α (or 1/Q) is set equal to √2, providing a
Butterworth (maximally flat) response characteristic. The filter
corner frequency is normalized to 1 kHz, with resistor values
shown in both rounded and (exact) form. Various other two-pole
response shapes are also possible with appropriate selection of
α. For a given response type (α), frequency can be easily scaled,
using proportional R or C values.
+VS
–VS
U1A
OP279
1
3
2
4
8
IN
R2
22k
(22.508k )
R1
11k
(11.254k )
C2
0.01 F
R = R2
0.1 F
Zf (HIGH PASS)
C1
0.01 F
GIVEN: ALPHA, F
SET C1 = C2 = C
ALPHA = 2/(N^0.5) = 1/Q
N = 4/(ALPHA)^2 = R2/R1
R1 = 1/(2*PI*F*C* (N^0.5))
R2 = N*R1
1kHz BW SHOWN
OUT
7
5
6
R = R1+R2
Zf (LOW PASS)
GIVEN: ALPHA, F
SET R1 = R2 = R
ALPHA = 2/(M^0.5) = 1/Q
N = 4/(ALPHA)^2 = C2/C1
PICK C1
C1 = M*C1
R = 1/(2*P1*F*C1* (M^0.5))
1kHz BW SHOWN
IN
R2
11k
(11.254k )
C2
0.01 F
0.1 F
C1
0.02 F
OUT
U1B
OP279
R1
11k
(11.254k )
a. High Pass
b. Low Pass
Figure 14. Two-Pole Unity-Gain Sallen Key HP/LP Filters
Low Pass Configurations
In the LP SK arrangement of Figure 14b, R and C elements are
interchanged, and the resistors are made equal. Here the C2/C1
ratio “M” is used to set the filter
α, as noted. This design is begun
with the choice of a standard capacitor value for C1 and a calcu-
lation of M, which forces a value of “M
× C1” for C2. Then, the
value “R” for R1 and R2 is calculated as per the expression.
For highest performance, the passive components used for tun-
ing active filters deserve attention. Resistors should be 1%, low
TC, metal film types of the RN55 or RN60 style, or similar.
A Single-Supply Headphone Amplifier
Because of its high speed and large output drive, the OP179/P279
makes for an excellent headphone driver, as illustrated in Figure
13. Its low supply operation and rail-to-rail inputs and outputs
give a maximum signal swing on a single 5 V supply. To ensure
maximum signal swing available to drive the headphone, the
amplifier inputs are biased to V+/2, which is in this case 2.5 V.
The 100 k
resistor to the positive supply is equally split into
two 50 k
with their common point bypassed by 10 F to pre-
vent power supply noise from contaminating the audio signal.
16
50k
220 F
LEFT
HEADPHONE
10 F
50k
100k
10 F
LEFT
INPUT
+V + 5V
1/2
OP279
16
50k
220 F
RIGHT
HEADPHONE
10 F
50k
100k
10 F
RIGHT
INPUT
+V
+V + 5V
1/2
OP279
Figure 13. A Single-Supply, Stereo Headphone Driver
The audio signal is then ac-coupled to each input through a
10
F capacitor. A large value is needed to ensure that the
20 Hz audio information is not blocked. If the input already has
the proper dc bias, the ac coupling and biasing resistors are not
required. A 220
F capacitor is used at the output to couple the
amplifier to the headphone. This value is much larger than that
used for the input because of the low impedance of the head-
phones, which can range from 32
to 600 . An additional
16
resistor is used in series with the output capacitor to pro-
tect the op amp’s output stage by limiting capacitor discharge
current. When driving a 48
load, the circuit exhibits less than
0.02% THD+N at low output drive levels (not shown). The
OP179/OP279’s high current output stage can drive this heavy
load to 4 V p-p and maintain less than 1% THD+N.
Active Filters
Several active filter topologies are useful with the OP179/OP279.
Among these are two popular architectures, the familiar Sallen-
Key (SK) voltage controlled voltage source (VCVS) and the
multiple feedback (MFB) topologies. These filter types can be
arranged for high pass (HP), low pass (LP), and band-pass (BP)
filters. The SK filter type uses the op amp as a fixed gain voltage
follower at unity or a higher gain, while the MFB structure uses
it as an inverting stage. Discussed here are simplified, 2-pole
forms of these filters, highly useful as system building blocks.
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| OP279GSZ-REEL | 功能描述:IC OPAMP GP R-R 5MHZ DUAL 8SOIC RoHS:是 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:1,000 系列:- 放大器类型:电压反馈 电路数:4 输出类型:满摆幅 转换速率:33 V/µs 增益带宽积:20MHz -3db带宽:30MHz 电流 - 输入偏压:2nA 电压 - 输入偏移:3000µV 电流 - 电源:2.5mA 电流 - 输出 / 通道:30mA 电压 - 电源，单路/双路(±):4.5 V ~ 16.5 V，±2.25 V ~ 8.25 V 工作温度:-40°C ~ 85°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) |
| OP279GSZ-REEL7 | 功能描述:IC OPAMP GP R-R 5MHZ DUAL 8SOIC RoHS:是 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:1,000 系列:- 放大器类型:电压反馈 电路数:4 输出类型:满摆幅 转换速率:33 V/µs 增益带宽积:20MHz -3db带宽:30MHz 电流 - 输入偏压:2nA 电压 - 输入偏移:3000µV 电流 - 电源:2.5mA 电流 - 输出 / 通道:30mA 电压 - 电源，单路/双路(±):4.5 V ~ 16.5 V，±2.25 V ~ 8.25 V 工作温度:-40°C ~ 85°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) |
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