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PDF OP179 Data sheet ( Hoja de datos )
| Número de pieza | OP179 | |
| Descripción | Rail-to-Rail High Output Current Operational Amplifiers | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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a
Rail-to-Rail High Output
Current Operational Amplifiers
FEATURES
Rail-to-Rail Inputs and Outputs
High Output Current: ؎60 mA
Single Supply: 5 V to 12 V
Wide Bandwidth: 5 MHz
High Slew Rate: 3 V/s
Low Distortion: 0.01%
Unity-Gain Stable
No Phase Reversal
Short-Circuit Protected
Drives Capacitive Loads: 10 nF
APPLICATIONS
Multimedia
Telecom
DAA Transformer Driver
LCD Driver
Low Voltage Servo Control
Modems
FET Drivers
GENERAL DESCRIPTION
The OP179 and OP279 are rail-to-rail, high output current,
single-supply amplifiers. They are designed for low voltage
applications that require either current or capacitive load drive
capability. The OP179/OP279 can sink and source currents of
± 60 mA (typical) and are stable with capacitive loads to 10 nF.
Applications that benefit from the high output current of the
OP179/OP279 include driving headphones, displays, transform-
ers and power transistors. The powerful output is combined with a
unique input stage that maintains very low distortion with wide
common-mode range, even in single supply designs.
The OP179/OP279 can be used as a buffer to provide much
greater drive capability than can usually be provided by CMOS
outputs. CMOS ASICs and DAC often have outputs that can
swing to both the positive supply and ground, but cannot drive
more than a few milliamps.
Bandwidth is typically 5 MHz and the slew rate is 3 V/µs, making
these amplifiers well suited for single supply applications that
require audio bandwidths when used in high gain configurations.
Operation is guaranteed from voltages as low as 4.5 V, up to 12 V.
OP179/OP279
PIN CONFIGURATIONS
5-Lead SOT-23-5
(RT-5)
OP179
OUT A 1
5 V–
V+ 2
+IN A 3
4 ؊IN A
8-Lead SOIC
(S Suffix)
NC 1
؊IN A 2
+IN A 3
V؊ 4
OP179
8 NC
7 V+
6 OUT A
5 NC
NC = NO CONNECT
8-Lead SOIC and TSSOP
SO-8 (S) and RU-8
OUT A 1
؊IN A 2
+IN A 3
V؊ 4
OP279
8 V+
7 OUT B
6 ؊IN B
5 +IN B
Very good audio performance can be attained when using the
OP179/OP279 in 5 volt systems. THD is below 0.01% with a
600 Ω load, and noise is a respectable 21 nV/√Hz. Supply current
is less than 3.5 mA per amplifier.
The single OP179 is available in the 5-lead SOT-23-5 package.
It is specified over the industrial (–40°C to +85°C) tempera-
ture range.
The OP279 is available in 8-lead TSSOP and SO-8 surface
mount packages. They are specified over the industrial (–40°C
to +85°C) temperature range.
REV. G
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2002
1 page  
6.5
6.0
VS ؍ ؎6V
5.5
VS ؍ ؎5V
5.0
VS ؍ 5V
4.5 VCM ؍ 2.5V
4.0
–50
–25 0 25 50 75
TEMPERATURE – ؇C
TPC 10. Supply Current vs.
Temperature
100
5
+EDGE
4
–EDGE
3
2
1
VS ؍ ؎5V
RL ؍ 1k⍀
CL ؍ +1nF
0
–50 –25 0 25 50 75
TEMPERATURE – ؇C
100
TPC 11. Slew Rate vs. Temperature
OP179/OP279
120 270
VS ؎2.5V
100
TA –40؇C
225
RL ؍ 2k⍀
80
GAIN
CL ؍ 500pF
180
60 135
40
PHASE
20
90
45
00
–20 –45
–40
100
1k 10k 100k 1M
FREQUENCY – Hz
–90
10M
TPC 12. Open-Loop Gain and
Phase vs. Frequency
120
VS ؎2.5V
100 TA ؍ 25؇C
80 –PSRR
60
+PSRR
40
20
0
10 100 1k 10k 100k 1M 10M
FREQUENCY – Hz
TPC 13. Power Supply Rejection vs.
Frequency
6
TA ؍ 25؇C
5 VS ؍ ؎2.5V
AVCL ؍ +1
RL 1k⍀
4
3
2
1
0
1k 10k 100k 1M 10M
FREQUENCY – Hz
TPC 14. Maximum Output
Swing vs. Frequency
180
160
TA ؍ 25؇C
VS ؍ ؎2.5V OR ؎5V
140
120
AVCL ؍ 10 OR 100
100
80
60
40
20
0
10
AVCL ؍ 1
100 1k 10k 100k 1M 10M
FREQUENCY – Hz
TPC 15. Closed-Loop Output
Impedance vs. Frequency
12
TA ؍ 25؇C
10
VS ؍ ؎5V
AVCL ؍ +1
RL 1k⍀
8
6
4
2
0
1k 10k 100k 1M 10M
FREQUENCY – Hz
TPC 16. Maximum Output Swing vs.
Frequency
50
AVCL ؍ +100
40
30
AVCL ؍ +10
20
VS ؎2.5V
TA ؍ 25؇C
RL 1k⍀
10
AVCL ؍ +1
0
–10
–20
–30
1k
10k 100k 1M 10M 100M
FREQUENCY – Hz
TPC 17. Closed-Loop Gain vs.
Frequency
80
TA ؍ 25؇C
70 AVCL ؍ +1
RL 1k⍀
60 VS ؎2.5V
VIN ؍ 100mV p-p
50
40
30
POSITIVE EDGE AND
20 NEGATIVE EDGE
10
0 0 2k 4k 6k 8k 10k
LOAD CAPACITANCE – pF
TPC 18. Small Signal Overshoot vs.
Load Capacitance
REV. G
–5–
5 Page 
OP179/OP279
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 kΩ resistor to the positive supply is equally split into
two 50 kΩ with their common point bypassed by 10 µF to pre-
vent power supply noise from contaminating the audio signal.
+V + 5V
50k⍀
50k⍀
10F
LEFT
INPUT
10F
100k⍀
+V + 5V
1/2
OP279
16⍀ 220F
50k⍀
LEFT
HEADPHONE
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.
+V
50k⍀
50k⍀
RIGHT
INPUT
10F
10F
100k⍀
1/2
OP279
16⍀ 220F
50k⍀
RIGHT
HEADPHONE
Figure 13. A Single-Supply, Stereo Headphone Driver
The audio signal is then ac-coupled to each input through a
10 µF 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 µF 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 Ω to 600 Ω. An additional
16 Ω 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 Ω 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.
C1
0.01F
IN
C2
0.01F
R2
22k⍀
(22.508k⍀)
R1
11k⍀
(11.254k⍀)
IN
R2
11k⍀
(11.254k⍀)
C2
0.01F
R1
11k⍀
(11.254k⍀)
+VS U1A
3 8 OP279
1
2
4
–VS
R = R2
0.1F
Zf (HIGH PASS)
OUT
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
a. High Pass
C1
0.02F
OUT
U1B
5 OP279
7
6
GIVEN: ALPHA, F
SET R1 = R2 = R
ALPHA = 2/(M^0.5) = 1/Q
N = 4/(ALPHA)^2 = C2/C1
R = R1+R2
0.1F
PICK C1
C1 = M*C1
R = 1/(2*P1*F*C1* (M^0.5))
1kHz BW SHOWN
Zf (LOW 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.
REV. G
–11–
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet OP179.PDF ] | |
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