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參數(shù)資料
| 型號： | OP279 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Rail-to-Rail High Output Current Operational Amplifier(滿幅度高輸出電流運放) |
| 中文描述： | 軌到軌高輸出電流運算放大器（滿幅度高輸出電流運放） |
| 文件頁數(shù)： | 9/16頁 |
| 文件大?。?/td> | 327K |
| 代理商： | OP279 |
OP279
–9–
REV. D
ON-OFF settling time of the circuit, R2 can be reduced to
50 k
or less. Although the integrator’s time constant chosen
here is 1 ms, room exists to trade off circuit bandwidth and
noise by increasing R3 and decreasing C2. T he SHUT DOWN
feature is maintained in the circuit with the simple addition of a
PNP transistor and a 10 k
resistor. One caveat with this
approach should be mentioned: although rail-to-rail output
amplifiers work best in the application, these operational ampli-
fiers require a finite amount (mV) of headroom when required
to provide any load current. T he choice for the circuit’s nega-
tive supply should take this issue into account.
R4
10
V
1/2
OP279
+5V
–10V
R3
1k
V
C2
1
m
F
C1
1
m
F
R2
100k
V
U1
REF195
GND
R5
10k
V
R1
10k
V
2N3904
4
6
2
3
SHUTDOWN
TTL/CMOS
+5V
–V
REF
U1
REF192
REF193
REF196
REF194
V
OUT
(V)
2.5
3.0
3.3
4.5
Figure 29. A Negative Precision Voltage Reference That
Uses No Precision Resistors Exhibits High Output Current
Drive
A High Output Current, Buffered Reference/Regulator
Many applications require stable voltage outputs relatively close
in potential to an unregulated input source. T his “l(fā)ow dropout”
type of reference/regulator is readily implemented with a rail-to-
rail output op amp, and is particularly useful when using a
higher current device such as the OP279. A typical example is
the 3.3 V or 4.5 V reference voltage developed from a 5 V sys-
tem source. Generating these voltages requires a three-terminal
reference, such as the REF196 (3.3 V) or the REF194 (4.5 V),
both of which feature low power, with sourcing outputs of
30 mA or less. Figure 30 shows how such a reference can be
outfitted with a OP279 buffer for higher currents and/or voltage
levels, plus sink and source load capability.
C2
0.1
m
F
R2
10k
V
1%
U2
1/2 OP279
V
=
3.3V @ 30mA
R5
1
V
C5
10
F/25V
TANTALUM
R1
10k
V
1%
C1
0.1
m
F
+V
S
+5V
V
OUT2
=
C4
1
m
F
6
2
3
4
V
COMMON
C3
0.1
m
F
V
C
ON/OFF
CONTROL
INPUT CMOS HI
(OR OPEN) = ON
LO = OFF
V
COMMON
R3
(SEE TEXT)
R4
3.3k
V
U1
REF196
Figure 30. A High Output Current Reference/Regulator
T he low dropout performance of this circuit is provided by stage
U2, one half of an OP279 connected as a follower/buffer for the
basic reference voltage produced by U1. T he low voltage satura-
tion characteristic of the OP279 allows up to 30 mA of load
current in the illustrated use, as a 5 V to 3.3 V converter with
high dc accuracy. In fact, the dc output voltage change for a
30 mA load current delta measures less than 1 mV. T his corre-
sponds to an equivalent output impedance of < 0.03
. In this
application, the stable 3.3 V from U1 is applied to U2 through a
noise filter, R1-C1. U2 replicates the U1 voltage within a few
mV, but at a higher current output at V
OUT 1
, with the ability to
both sink and source output current(s)—unlike most IC refer-
ences. R2 and C2 in the feedback path of U2 provide bias
compensation for lowest dc error and additional noise filtering.
T ransient performance of the reference/regulator for a 10 mA
step change in load current is also quite good and is determined
largely by the R5-C5 output network. With values as shown, the
transient is about 10 mV peak and settles to within 2 mV in
8
μ
s, for either polarity. Although room exists for optimizing the
transient response, any changes to the R5-C5 network should be
verified by experiment to preclude the possibility of excessive
ringing with some capacitor types.
T o scale V
OUT 2
to another (higher) output level, the optional
resistor R3 (shown dotted) is added, causing the new V
OUT 1
to
become:
V
OUT 1
=
V
OUT
2
×
1
+
R
2
R
3
As an example, for a V
OUT 1
= 4.5 V, and V
OUT 2
= 2.5 V from a
REF192, the gain required of U2 is 1.8 times, so R2 and R3
would be chosen for a ratio of 0.8:1, or 18 k
:22.5 k
. Note
that for the lowest V
OUT 1
dc error, the parallel combination of
R2 and R3 should be maintained equal to R1 (as here), and the
R2-R3 resistors should be stable, close tolerance metal film
types.
T he circuit can be used either as shown as a 5 V to 3.3 V
reference/regulator, or it can also be used with ON/OFF con-
trol. By driving Pin 3 of U1 with a logic control signal as noted,
the output is switched ON/OFF. Note that when ON/OFF
control is used, resistor R4 should be used with U1 to speed
ON-OFF switching.
Direct Access Arrangement for T elephone Line Interface
Figure 31 illustrates a +5 V only transmit/receive telephone line
interface for 110
transmission systems. It allows full duplex
transmission of signals on a transformer coupled 110
line in a
differential manner. Amplifier A1 provides gain that can be
adjusted to meet the modem output drive requirements. Both
A1 and A2 are configured so as to apply the largest possible
signal on a single supply to the transformer. Because of the
OP279’s high output current drive and low dropout voltage, the
largest signal available on a single +5 V supply is approximately
4.5 V p-p into a 110
transmission system. Amplifier A3 is
configured as a difference amplifier to extract the receive signal
from the transmission line for amplification by A4. A4’s gain
can be adjusted in the same manner as A1’s to meet the
modem’s input signal requirements. Standard resistor values
permit the use of SIP (Single In-line Package) format resistor
arrays. Couple this with the OP279’s 8-pin SOIC footprint and
this circuit offers a compact, cost-sensitive solution.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OP2790006SR | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| OP279GP | 制造商:Analog Devices 功能描述:OP AMP DUAL HIGH O/P RRI/O 279 制造商:Analog Devices Inc. 功能描述:Rail-to-Rail High Output Current Operational Amplifiers |
| OP279GRU | 制造商:AD 制造商全稱:Analog Devices 功能描述:Rail-to-Rail High Output Current Operational Amplifiers |
| OP279GRU-REEL | 制造商:Analog Devices 功能描述:OP Amp Dual GP R-R I/O 制造商:Rochester Electronics LLC 功能描述:RAIL-RAIL HI OUTPUT OPAMP - Tape and Reel |
| OP279GRUZ-REEL | 功能描述:IC OPAMP GP R-R 5MHZ DUAL 8TSSOP RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 產(chǎn)品培訓(xùn)模塊:Differential Circuit Design Techniques for Communication Applications 標(biāo)準(zhǔn)包裝:1 系列:- 放大器類型:RF/IF 差分 電路數(shù):1 輸出類型:差分 轉(zhuǎn)換速率:9800 V/µs 增益帶寬積:- -3db帶寬:2.9GHz 電流 - 輸入偏壓:3µA 電壓 - 輸入偏移:- 電流 - 電源:40mA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):3 V ~ 3.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-VQFN 裸露焊盤，CSP 供應(yīng)商設(shè)備封裝:16-LFCSP-VQ 包裝:剪切帶 (CT) 產(chǎn)品目錄頁面:551 (CN2011-ZH PDF) 其它名稱:ADL5561ACPZ-R7CT |
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