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參數(shù)資料
| 型號： | AD549KHZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 5/20頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC OPAMP GP 1MHZ LP 20MA TO99-8 |
| 標(biāo)準(zhǔn)包裝： | 1 |
| 系列： | Topgate™ |
| 放大器類型： | 通用 |
| 電路數(shù)： | 1 |
| 轉(zhuǎn)換速率： | 3 V/µs |
| 增益帶寬積： | 1MHz |
| 電流 - 輸入偏壓： | 0.075pA |
| 電壓 - 輸入偏移： | 150µV |
| 電流 - 電源： | 600µA |
| 電流 - 輸出 / 通道： | 20mA |
| 電壓 - 電源，單路/雙路(±)： | ±5 V ~ 18 V |
| 工作溫度： | 0°C ~ 70°C |
| 安裝類型： | 通孔 |
| 封裝/外殼： | TO-99-8 金屬罐 |
| 供應(yīng)商設(shè)備封裝： | TO-99-8 |
| 包裝： | 散裝 |
| 產(chǎn)品目錄頁面： | 773 (CN2011-ZH PDF) |
AD549
Rev. H | Page 13 of 20
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AD549
SOURCE
RPROTECT
DIFFERENTIAL INPUT VOLTAGE OVERLOAD
A plot of the AD549 input currents vs. differential input
input current at either terminal stays below a few hundred
femtoamps until one input terminal is forced higher than 1 V
to 1.5 V above the other terminal. Under these conditions, the
input current limits at 30 μA.
Figure 38. Follower with Input Current Limit
Figure 39 is a schematic of the AD549 as an inverter with an
input voltage clamp. Bootstrapping the clamp diodes at the
inverting input minimizes the voltage across the clamps and
keeps the leakage due to the diodes low. Use low leakage diodes,
such as the FD333s, and shield them from light to prevent photo-
currents from being generated. Even with these precautions, the
diodes measurably increase input current and capacitance.
100
10
1
100n
10n
1n
100p
10p
1p
100f
10f
–5
–4
–3
–2
–1
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DIFFERENTIAL INPUT VOLTAGE (V) (VIN+ – VIN–)
INP
UT
CURR
E
NT
(A)
IIN–IIN+
0
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AD549
SOURCE
RF
PROTECT
DIODES
Figure 39. Input Voltage Clamp with Diodes
SAMPLE-AND-DIFFERENCE CIRCUIT TO MEASURE
ELECTROMETER LEAKAGE CURRENTS
Figure 36. Input Current vs. Differential Input Voltage
INPUT PROTECTION
There are a number of methods used to test electrometer leakage
currents, including current integration and direct I-to-V con-
version. Regardless of the method used, board and interconnect
cleanliness, proper choice of insulating materials (such as Teflon
or Kel-F), correct guarding and shielding techniques, and care
in physical layout are essential to making accurate leakage
measurements.
The AD549 safely handles any input voltage within the supply
voltage range. Subjecting the input terminals to voltages beyond
the power supply can destroy the device or cause shifts in input
current or offset voltage if the amplifier is not protected.
A protection scheme for the amplifier as an inverter is shown
inverting input to 1 mA for expected transient (less than 1 sec)
overvoltage conditions, or to 100 μA for a continuous overload.
Because RP is inside the feedback loop and is much lower in
value than the amplifier input resistance, it does not affect the
dc gain of the inverter. However, the Johnson noise of the
resistor adds root sum of squares to the amplifier input noise.
Figure 40 is a schematic of the sample-and-difference circuit. It
uses two AD549 electrometer amplifiers (A and B) as I-to-V
converters with high value (1010 Ω) sense resistors (RSa and
RSb). R1 and R2 provide for an overall circuit sensitivity of
10 fA/mV (10 pA full scale). CC and CF provide noise suppression
and loop compensation. CC should be a low leakage polystyrene
capacitor. An ultralow leakage Kel-F test socket is used for con-
tacting the device under test. Rigid Teflon coaxial cable is used
to make connections to all high impedance nodes. The use of
rigid coaxial cable affords immunity to error induced by mechan-
ical vibration and provides an outer conductor for shielding. The
entire circuit is enclosed in a grounded metal box.
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AD549
CF
SOURCE
RPROTECT
RF
Figure 37. Inverter with Input Current Limit
In the corresponding version of this scheme for a follower,
terminal produce a pole in the signal frequency response at a
f = πRC. Again, the Johnson noise, RP, adds to the input
voltage noise of the amplifier.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD549L | 制造商:AD 制造商全稱:Analog Devices 功能描述:Ultralow Input Bias Current Operational Amplifier |
| AD549LH | 功能描述:IC OPAMP GP 1MHZ LP 20MA TO99-8 RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:Topgate™ 標(biāo)準(zhǔn)包裝:50 系列:- 放大器類型:J-FET 電路數(shù):2 輸出類型:- 轉(zhuǎn)換速率:3.5 V/µs 增益帶寬積:1MHz -3db帶寬:- 電流 - 輸入偏壓:30pA 電壓 - 輸入偏移:2000µV 電流 - 電源:200µA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):7 V ~ 36 V，±3.5 V ~ 18 V 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:8-DIP（0.300"，7.62mm） 供應(yīng)商設(shè)備封裝:8-PDIP 包裝:管件 |
| AD549LH | 制造商:Analog Devices 功能描述:OP AMP U-LOW BIAS TO-99-8 549 |
| AD549LH/+ | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Voltage-Feedback Operational Amplifier |
| AD549LHZ | 功能描述:IC OPAMP GP 1MHZ LP 20MA TO99-8 RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:Topgate™ 標(biāo)準(zhǔn)包裝:50 系列:- 放大器類型:J-FET 電路數(shù):2 輸出類型:- 轉(zhuǎn)換速率:3.5 V/µs 增益帶寬積:1MHz -3db帶寬:- 電流 - 輸入偏壓:30pA 電壓 - 輸入偏移:2000µV 電流 - 電源:200µA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):7 V ~ 36 V，±3.5 V ~ 18 V 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:8-DIP（0.300"，7.62mm） 供應(yīng)商設(shè)備封裝:8-PDIP 包裝:管件 |
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