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| 型號： | OP484ESZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 6/24頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC OPAMP GP R-R 4.25MHZ 14SOIC |
| 標(biāo)準(zhǔn)包裝： | 56 |
| 放大器類型： | 通用 |
| 電路數(shù)： | 4 |
| 輸出類型： | 滿擺幅 |
| 轉(zhuǎn)換速率： | 4 V/µs |
| 增益帶寬積： | 4.25MHz |
| 電流 - 輸入偏壓： | 80nA |
| 電壓 - 輸入偏移： | 150µV |
| 電流 - 電源： | 2.25mA |
| 電流 - 輸出 / 通道： | 10mA |
| 電壓 - 電源，單路/雙路(±)： | 3 V ~ 36 V，±1.5 V ~ 18 V |
| 工作溫度： | -40°C ~ 125°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 14-SOIC（0.154"，3.90mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 14-SOIC |
| 包裝： | 管件 |
| 產(chǎn)品目錄頁面： | 774 (CN2011-ZH PDF) |
OP184/OP284/OP484
Rev. J | Page 14 of 24
APPLICATIONS INFORMATION
FUNCTIONAL DESCRIPTION
The OP184/OP284/OP484 are precision single-supply, rail-to-rail
operational amplifiers. Intended for the portable instrumentation
marketplace, the OPx84 family of devices combine the attributes
of precision, wide bandwidth, and low noise to make them a superb
choice in single-supply applications that require both ac and
precision dc performance. Other low supply voltage appli-
cations for which the OP284 is well suited are active filters,
audio microphone preamplifiers, power supply control, and
telecommunications. To combine all of these attributes with
rail-to-rail input/output operation, novel circuit design techniques
are used.
D1
D2
Q4
V+
I1
Q3
2
Q
1
Q
I2
V01
V02
–I N x
V–
+IN x
00293-
044
–
R4
3k
R3
3k
R2
4k
R1
4k
Figure 44. OP284 Equivalent Input Circuit
For example, Figure 44 illustrates a simplified equivalent circuit
for the input stage of the OP184/OP284/OP484. It comprises
an NPN differential pair, Q1→Q2, and a PNP differential pair,
Q3→Q4, operating concurrently. Diode Network D1→Diode
Network D2 serves to clamp the applied differential input
voltage to the OP284, thereby protecting the input transistors
against avalanche damage. Input stage voltage gains are kept low
for input rail-to-rail operation. The two pairs of differential
output voltages are connected to the second stage of the OP284,
which is a compound folded cascade gain stage. It is also in the
second gain stage, where the two pairs of differential output
voltages are combined into a single-ended, output signal voltage
used to drive the output stage. A key issue in the input stage is
the behavior of the input bias currents over the input common-
mode voltage range. Input bias currents in the OP284 are the
arithmetic sum of the base currents in Q1→Q3 and in Q2→Q4.
As a result of this design approach, the input bias currents in
the OP284 not only exhibit different amplitudes; they also
exhibit different polarities. This effect is best illustrated by
Figure 10. It is, therefore, of paramount importance that the
effective source impedances connected to the OP284 inputs
be balanced for optimum dc and ac performance.
To achieve rail-to-rail output, the OP284 output stage design
employs a unique topology for both sourcing and sinking current.
This circuit topology is illustrated in Figure 45. The output stage
is voltage-driven from the second gain stage. The signal path
through the output stage is inverting; that is, for positive input
signals, Q1 provides the base current drive to Q6 so that it conducts
(sinks) current. For negative input signals, the signal path via
Q1→Q2→D1→Q4→Q3 provides the base current drive for Q5 to
conduct (source) current. Both amplifiers provide output current
until they are forced into saturation, which occurs at approxi-
mately 20 mV from the negative supply rail and 100 mV from
the positive supply rail.
00293-
045
V+
I2
I1
Q1
Q3
Q4
Q2
V–
Q5
VOUT
Q6
R6
R3
R2
R1
R4
R5
D1
INPUT FROM
SECOND GAIN
STAGE
Figure 45. OP284 Equivalent Output Circuit
Thus, the saturation voltage of the output transistors sets the
limit on the OP284 maximum output voltage swing. Output
short-circuit current limiting is determined by the maximum
signal current into the base of Q1 from the second gain stage.
Under output short-circuit conditions, this input current level
is approximately 100 A. With transistor current gains around 200,
the short-circuit current limits are typically 20 mA. The output
stage also exhibits voltage gain. This is accomplished by the use
of common-emitter amplifiers, and, as a result, the voltage gain
of the output stage (thus, the open-loop gain of the device)
exhibits a dependence to the total load resistance at the output
of the OP284.
INPUT OVERVOLTAGE PROTECTION
As with any semiconductor device, if conditions exist where the
applied input voltages to the device exceed either supply voltage,
the input overvoltage I-V characteristic of the device must be
considered. When an overvoltage occurs, the amplifier could be
damaged, depending on the magnitude of the applied voltage
and the magnitude of the fault current. Figure 46 illustrates the
overvoltage I-V characteristic of the OP284. This graph was
generated with the supply pins connected to GND and a curve
tracer’s collector output drive connected to the input.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| OP484ESZ | 制造商:Analog Devices 功能描述:Operational Amplifier (Op-Amp) IC |
| OP484ESZ-REEL | 功能描述:IC OPAMP GP R-R 4.25MHZ 14SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:Excalibur™ 放大器類型:J-FET 電路數(shù):1 輸出類型:- 轉(zhuǎn)換速率:45 V/µs 增益帶寬積:10MHz -3db帶寬:- 電流 - 輸入偏壓:20pA 電壓 - 輸入偏移:490µV 電流 - 電源:1.7mA 電流 - 輸出 / 通道:48mA 電壓 - 電源，單路/雙路(±):4.5 V ~ 38 V，±2.25 V ~ 19 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應(yīng)商設(shè)備封裝:8-SOIC 包裝:帶卷 (TR) |
| OP484F | 制造商:Analog Devices 功能描述: |
| OP484F8Z | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述: |
| OP484FP | 制造商:Analog Devices 功能描述:OP Amp Quad GP R-R I/O 制造商:Rochester Electronics LLC 功能描述:PREC RAIL TO RAIL OP AMP - Bulk 制造商:Analog Devices 功能描述:AMPLIFIER IC NUMBER OF CIRCUITS:4 |
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