Plastic Package. Plastic Micropackage. Part Number. Example : LFN. These circuits are monolithic J-FET input operational. J-FET on the same chip with standard bipolar transis-.
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Plastic Package. Plastic Micropackage. Part Number. Example : LFN. These circuits are monolithic J-FET input operational.
J-FET on the same chip with standard bipolar transis-. This amplifiers feature low input bias and offset cur-. The devices are also designed for high slew rate, wide. July FETinput transistors. TheseJFETs havelarge reverse.
However, neitherof thenegativein-. Exceeding the negative. In neithercasedoes. Theseamplifiers will operatewith. In fact, the common-modevoltagecanex-. The positive suplly can there-. FET input op amps they do not require special han-. Allof thebiascurrentsintheseamplifiersareset by FET. The drain currents for the amplifiers. As with most amplifiers, care should betakenwith lead. For example, resistors from. A feedback pole is createdwhen the feedbackaround. The parallel resistance and.
However, if the feedback pole is less. The value of that added. This amplifiers feature low input bias and offset cur- rents, low input offset voltage and input offset voltage drift,coupledwith offsetadjust which doesnot degrade drift or common-mode rejection.
TheseJFETs havelarge reverse breakdown voltagesfromgatetosource or drain elimi- natingtheneed of clamps across the inputs. Therefore large differential input voltages can easily be accom- modatedwithoutalarge increaseof inputcurrents.
The maximum differential input voltage is independent of the supply voltage. However, neitherof thenegativein- put voltagesshouldbe allowed to exceedthe negative supply as this will cause large currents to flow which can result in a destroyed unit.
Exceeding the negative common-modelimit on either inputwill causeareversal of thephasetotheoutputandforce the amplifier output to the correspondinghigh or lowstate. Exceedingthe negativecommon-mode limit on bothinputs will force the amplifier outputto a highstate.
In neithercasedoes a latch occur since raising the input back within the common-mode range again puts the input stage and thustheamplifierin a normal operatingmode. Exceed- ingthepositive common-modelimit on asingle input will not changethephase of the output however, if bothin- putsexceedthe limit, theoutput of theamplifier will be forcedto ahighstate.
Theseamplifiers will operatewith the common-mode input voltage equal to the positive supply. In fact, the common-modevoltagecanex- ceedthepositivesupplyby approximately mV inde- pendentof supply volt-age and over thefull operat- ingtemperaturerange.
Precautions- shouldbe taken to ensurethat thepowersupply forthe integrated circuit never becomes re-versed in polarity or that the unit is not inadvertentlyin-stalledbackwards in a socket as an unilimited current surge throughthe resulting forward diode within the IC couldcausefusin- goftheinternalconductorsandresultin a destroyedunit.
Allof thebiascurrentsintheseamplifiersareset by FET current sources. The drain currents for the amplifiers are therefore essentially independent of supply volt- ages. As with most amplifiers, care should betakenwith lead dress, components placement and supply decoupling in order to ensure stability. A feedback pole is createdwhen the feedbackaround any amplifier is resistive. The parallel resistance and capacitancefromthe input of thedevice usually the in- vertinginput toacgroundsetthefrequencyofthepole.
In many instances the frequency of this pole is much greaterthanthe expected3 dBfrequencyof the closed loopgain and consequentlythereisnegligible effect on stability margin. However, if the feedback pole is less than approximately six time the expected 3 dB fre- quencyaleadcapacitor should be placed from the out- put to the input of the op amp. The value of that added capacitor should be such that the RC time constant of this capacitor and the resistance it parallels is greater than or equal to the original feedback pole time con- stant.
Fairchild Semiconductor. Motorola Inc. National Semiconductor. Texas Instruments. Analog Devices.
Datasheet LF155 LF156 LF256 LF257 LF355 LF356 LF357 TI
LF355 AMPLIFIERS. Datasheet pdf. Equivalent