參數(shù)資料
型號(hào)： LM611AIN
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 運(yùn)動(dòng)控制電子
英文描述： Operational Amplifier and Adjustable Reference
中文描述： OP-AMP, 0.5 MHz BAND WIDTH, PDIP8
封裝： PLASTIC, DIP-8
文件頁(yè)數(shù)： 11/17頁(yè)
文件大?。?/td> 735K
代理商： LM611AIN
Application Information
(Continued)
The reference equivalent circuit reveals how V
is held at the
constant 1.2V by feedback, and how the FEEDBACK pin
passes little current.
To generate the required reverse current, typically a resistor
is connected from a supply voltage higher than the reference
voltage. Varying that voltage, and so varying I
, has small ef-
fect with the equivalent series resistance of less than an ohm
at the higher currents.Alternatively, an active current source,
such as the LM134 series, may generate I
r
.
Capacitors in parallel with the reference are allowed. See the
Reference AC Stability Range curve for capacitance
values— from 20 μA to 3 mA any capacitor value is stable.
With the reference’s wide stability range with resistive and
capacitive loads, a wide range of RC filter values will perform
noise filtering.
Adjustable Reference
The FEEDBACK pin allows the reference output voltage,
V
, to vary from 1.24V to 6.3V. The reference attempts to
hold V
at 1.24V. If V
is above 1.24V, the reference will con-
duct current from Cathode to Anode; FEEDBACK current al-
ways remains low. If FEEDBACK is connected to Anode,
then V
= V
= 1.24V. For higher voltages FEEDBACK is
held at a constant voltage above Anode— say 3.76V for V
ro
=5V. Connecting a resistor across the constant V
generates
a current I=R1/V
flowing from Cathode into FEEDBACK
node.AThevenin equivalent 3.76V is generated from FEED-
BACK to Anode with R2=3.76/I. Keep I greater than one
thousand times larger than FEEDBACK bias current for
<
0.1% error— I
≥
32 μAfor the military grade over the military
temperature range (I
≥
5.5 μA for a 1% untrimmed error for a
commercial part.)
R1 = Vr/I = 1.24/32μ = 39k
R2 = R1 {(Vro/Vr) 1} = 39k {(5/1.24) 1)} = 118k
Understanding that V
is fixed and that voltage sources, re-
sistors, and capacitors may be tied to the FEEDBACK pin, a
range of V
r
temperature coefficients may be synthesized.
DS009221-15
FIGURE 2. Reference Equivalent Circuit
DS009221-16
FIGURE 3. 1.2V Reference
DS009221-17
FIGURE 4. Thevenin Equivalent of
Reference with 5V Output
DS009221-18
FIGURE 5. Resistors R1 and R2 Program
Reference Output Voltage to be 5V
DS009221-19
FIGURE 6. Output Voltage has Negative Temperature
Coefficient (TC) if R2 has Negative TC
DS009221-20
FIGURE 7. Output Voltage has Positive TC
if R1 has Negative TC
www.national.com
11
相關(guān)PDF資料
PDF描述
LM611AMN Operational Amplifier and Adjustable Reference
LM611BIN Operational Amplifier and Adjustable Reference
LM611CM Operational Amplifier and Adjustable Reference
LM611CN Operational Amplifier and Adjustable Reference
LM611IM Operational Amplifier and Adjustable Reference
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM611AMJ/883 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Operational Amplifier and Adjustable Reference
LM611AMN 制造商:Rochester Electronics LLC 功能描述:- Bulk
LM611BIN 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Operational Amplifier and Adjustable Reference
LM611C WAF 制造商:Texas Instruments 功能描述:
LM611CM 功能描述:運(yùn)算放大器 - 運(yùn)放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel
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