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參數(shù)資料
| 型號： | AD8602 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Precision CMOS Single Supply Rail-to-Rail Input/Output Wideband Operational Amplifiers |
| 中文描述： | 精密的CMOS單電源軌到軌輸入/輸出運算放大器寬帶 |
| 文件頁數(shù)： | 14/16頁 |
| 文件大小： | 255K |
| 代理商： | AD8602 |
AD8601/AD8602
–14–
REV. 0
Input Overvoltage Protection
As with any semiconductor device, if a condition could exist for
the input voltage to exceed the power supply, the device
’
s input
overvoltage characteristic must be considered. Excess input voltage
will energize internal PN junctions in the AD860x, allowing
current to flow from the input to the supplies.
This input current will not damage the ampli
fi
er provided it is
limited to 5 mA or less. This can be ensured by placing a resistor
in series with the input. For example, if the input voltage could
exceed the supply by 5 V, the series resistor should be at least
(5 V/5 mA) = 1 k
. With the input voltage within the supply
rails, a minimal amount of current is drawn into the inputs
which, in turn, causes a negligible voltage drop across the series
resistor. Thus, adding the series resistor will not adversely affect
circuit performance.
Overdrive Recovery
Overdrive recovery is de
fi
ned as the time it takes the output of an
ampli
fi
er to come off the supply rail when recovering from an over-
load signal. This is tested by placing the ampli
fi
er in a closed-loop
gain of 10 with an input square wave of 2 V peak-to-peak while the
ampli
fi
er is powered from either 5 V or 3 V.
The AD860x has excellent recovery time from overload conditions.
The output recovers from the positive supply rail within 200 ns at all
supply voltages. Recovery from the negative rail is within 500 ns
at 5 V supply, decreasing to within 350 ns when the device is
powered from 2.7 V.
Power-On Time
Power-on time is important in portable applications, where the
supply voltage to the ampli
fi
er may be toggled to shut down the
device to improve battery life. Fast power-up behavior ensures
the output of the ampli
fi
er will quickly settle to its
fi
nal voltage,
thus improving the power-up speed of the entire system. Once
the supply voltage reaches a minimum of 2.5 V, the AD860x
will settle to a valid output within 1
μ
s. This turn-on response
time is faster than many other precision ampli
fi
ers, which can
take tens or hundreds of microseconds for their output to settle.
Using the AD8602 in High Source Impedance Applications
The CMOS rail-to-rail input structure of the AD860x allows
these ampli
fi
ers to have very low input bias currents, typically
0.2 pA. This allows the AD860x to be used in any application
that has a high source impedance or must use large value resistances
around the ampli
fi
er. For example, the photodiode ampli
fi
er circuit
shown in Figure 3 requires a low input bias current op amp to
reduce output voltage error. The AD8601 minimizes offset errors
due to its low input bias current and low offset voltage.
The current through the photodiode is proportional to the incident
light power on its surface. The 4.7 M
resistor converts this
current into a voltage, with the output of the AD8601 increas-
ing at 4.7 V/
μ
A. The feedback capacitor reduces excess noise at
higher frequencies by limiting the bandwidth of the circuit to:
BW
C
F
=
)
1
2 4 7
.
M
(1)
Using a 10 pF feedback capacitor limits the bandwidth to approxi-
mately 3.3 kHz.
4.7m
10pF
(OPTIONAL)
D1
V
4.7V/ A
AD8601
Figure 3. Amplifier Photdiode Circuit
High- and Low-Side Precision Current Monitoring
Because of its low input bias current and low offset voltage, the
AD860x can be used for precision current monitoring. The true
rail-to-rail input feature of the AD860x allows the ampli
fi
er to
monitor current on either high-side or low-side. Using both
ampli
fi
ers in an AD8602 provides a simple method for monitoring
both current supply and return paths for load or fault detection.
Figure 4 and 54 demonstrate both circuits.
3V
RETURN TO
GROUND
1/2 AD8602
3V
R2
2.49k
MONITOR
OUTPUT
R1
100
R
0.1
Q1
2N3905
Figure 4. A Low-Side Current Monitor
3V
0.1 F
R
0.1
V+
I
L
Q1
2N3904
MONITOR
OUTPUT
3V
R2
2.49k
R1
100
1/2
AD8602
Figure 5. A High-Side Current Monitor
Voltage drop is created across the 0.1
resistor that is propor-
tional to the load current. This voltage appears at the inverting
input of the ampli
fi
er due to the feedback correction around the
op amp. This creates a current through R1 which, in turn, pulls
current through R2. For the low side monitor, the monitor
output voltage is given by:
Monitor Output
R
R
R
I
SENSE
1
L
=
×
×
2
(2)
For the high-side monitor, the monitor output voltage is:
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AD8602AR | Precision CMOS Single Supply Rail-to-Rail Input/Output Wideband Operational Amplifiers |
| AD8602ARM | Precision CMOS Single Supply Rail-to-Rail Input/Output Wideband Operational Amplifiers |
| AD8602DR | Precision CMOS Single Supply Rail-to-Rail Input/Output Wideband Operational Amplifiers |
| AD8602DRM | Precision CMOS Single Supply Rail-to-Rail Input/Output Wideband Operational Amplifiers |
| AD8605ACB-REEL | Precision Low noise CMOS Rail-to-Rail Input/Output Operational Amplifiers |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD8602A | 制造商:Analog Devices 功能描述: |
| AD8602AR | 功能描述:IC OPAMP GP CMOS 8.4MHZ 8SOIC RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:DigiTrim® 標準包裝:1,000 系列:- 放大器類型:電壓反饋 電路數(shù):4 輸出類型:滿擺幅 轉(zhuǎn)換速率:33 V/µs 增益帶寬積:20MHz -3db帶寬:30MHz 電流 - 輸入偏壓:2nA 電壓 - 輸入偏移:3000µV 電流 - 電源:2.5mA 電流 - 輸出 / 通道:30mA 電壓 - 電源，單路/雙路(±):4.5 V ~ 16.5 V，±2.25 V ~ 8.25 V 工作溫度:-40°C ~ 85°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:帶卷 (TR) |
| AD8602ARM | 制造商:Analog Devices 功能描述:Operational Amplifier, Dual AMP, CMOS, 8 Pin, Plastic, TSSOP 制造商:Analog Devices 功能描述:DUAL OP-AMP, 2100 uV OFFSET-MAX, 8.2 MHz BAND WIDTH, PDSO8 |
| AD8602ARM-R2 | 制造商:Analog Devices 功能描述:OP Amp Dual GP R-R I/O 5.5V 8-Pin MSOP T/R 制造商:Rochester Electronics LLC 功能描述:DUAL, PRECISION CMOS RAIL-RAIL OP AMP - Bulk |
| AD8602ARM-REEL | 功能描述:IC OPAMP GP CMOS 8.4MHZ 8MSOP RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:DigiTrim® 標準包裝:160 系列:- 放大器類型:通用 電路數(shù):4 輸出類型:滿擺幅 轉(zhuǎn)換速率:10 V/µs 增益帶寬積:9MHz -3db帶寬:- 電流 - 輸入偏壓:1pA 電壓 - 輸入偏移:250µV 電流 - 電源:730µA 電流 - 輸出 / 通道:28mA 電壓 - 電源，單路/雙路(±):2.7 V ~ 5.5 V，±1.35 V ~ 2.75 V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.154"，3.90mm 寬） 供應(yīng)商設(shè)備封裝:16-SOIC N 包裝:管件 |
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