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參數(shù)資料
| 型號： | AD549KHZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 8/20頁 |
| 文件大小： | 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 16 of 20
Frequency compensation is provided by R11, R12, C1, and C2.
The bandwidth of the circuit is 300 kHz at input signals greater
than 50 μA; bandwidth decreases smoothly with decreasing
signal levels.
To trim the circuit, set the input currents to 10 μA and trim the
A3 offset using the trim potentiometer of the amplifier for the
output to equal 0. Next, set I1 to 1 μA and adjust the output to
equal 1 V by trimming R10. Additional offset trims on Ampli-
fier A1 and Amplifier A2 can be used to increase the voltage
input accuracy and dynamic range.
The very low input current of the AD549 makes this circuit
useful over a very wide range of signal currents. The total input
current (which determines the low level accuracy of the circuit)
is the sum of the amplifier input current, the leakage across the
compensating capacitor (negligible if a polystyrene or Teflon
capacitor is used), and the collector-to-collector and collector-
to-base leakages of one side of the dual log transistors. The
magnitudes of these last two leakages depend on the amplifier
input offset voltage and are typically less than 10 fA with 1 mV
offsets. The low level accuracy is limited primarily by the
amplifier input current, only 60 fA maximum when the
AD549L is used.
The effects of the emitter resistance of Q1 and Q2 can degrade
circuit accuracy at input currents above 100 μA. The networks
composed of R13, D1, R16, R14, D2, and R17 compensate for
these errors, so that this circuit has less than a 1% log confor-
mance error at 1 mA input currents. The correct value for R13
and R14 depends on the type of log transistors used. The 49.9 kΩ
resistors were chosen for use with LM394 transistors. Smaller
resistance values are needed for smaller log transistors.
TEMPERATURE COMPENSATED pH PROBE
AMPLIFIER
A pH probe can be modeled as an mV-level voltage source
with a series source resistance dependent on the electrode
composition and configuration. The glass bulb resistance of a
typical pH electrode pair falls between 106 Ω and 109 Ω. It is
therefore important to select an amplifier with low enough
input currents such that the voltage drop produced by the
amplifier input bias current and the electrode resistance does
not become an appreciable percentage of a pH unit.
The circuit in Figure 46 illustrates the use of the AD549 as a pH
probe amplifier. As with other electrometer applications, the use of
guarding, shielding, and Teflon standoffs is necessary to capitalize
on the AD549 low input current. If an AD549L (60 fA maximum
input current) is used, the error contributed by the input current is
held below 60 μV for pH electrode source impedances up to 109 Ω.
Input offset voltages (which can be trimmed) are below 0.5 mV.
00
51
1-
0
45
3
2
6
5
1
4
A3
AD549
R10
2k
10k
OUTPUT
OFFSET
SCALE
FACTOR
ADJ
VOUT
R9
14.3k
R8
1k
*
R4
20k
4.99k
R6
20k
R7
15k
R15
1k
R5
20k
R3
20k
0.1F
+VS
FOR EACH AMPLIFIER
PIN 7
PIN 4
–VS
2
3
6
5
1
4
A2
AD549
V2
OFFSET
10k
D4
I2 IN
V2 IN
C2
100pF
R2
10k
Q2
B
D2
D1
I1 IN
2
6
5
1
4
A1
AD549
V1
OFFSET
10k
D3
3
V1 IN
R1
10k
Q1
A
C1
100pF
R11
4.99k
R14
49.9k
R16
10
R17
10
R13
49.9k
Q1, Q2 = LM394
DUAL LOG TRANSISTORS
D1, D4 1N4148 DIODES
R8, R15 1k + 350 ppm/°C TC RESISTOR
*TELLAB QB1 OR PRECISION RESISTOR PT146
ALL OTHER RESISTORS ARE 1% METAL FILM
VOUT = 1V × LOG10
V2
V1
VOUT = 1V × LOG10
I2
I1
Figure 45. Log Ratio 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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