LMC6034IM中文资料
LMC6034
CMOS Quad Operational Amplifier
General Description
The LMC6034is a CMOS quad operational amplifier which can operate from either a single supply or dual supplies.Its performance features include an input common-mode range that reaches ground,low input bias current,and high voltage gain into realistic loads,such as 2k ?and 600?.
This chip is built with National’s advanced Double-Poly Silicon-Gate CMOS process.
See the LMC6032datasheet for a CMOS dual operational amplifier with these same features.For higher performance characteristics refer to the LMC660.
Features
n Specified for 2k ?and 600?loads n High voltage gain:126dB
n Low offset voltage drift: 2.3μV/?C n Ultra low input bias current:40fA n Input common-mode range includes V ?
n Operating Range from +5V to +15V supply n I SS =400μA/amplifier;independent of V +n Low distortion:0.01%at 10kHz n Slew rate: 1.1V/μs
n
Improved performance over TLC274
Applications
n High-impedance buffer or preamplifier n Current-to-voltage converter n Long-term integrator n Sample-and-hold circuit n
Medical instrumentation
Connection Diagram
Ordering Information
Temperature Range
Package
NSC Drawing
Transport Media
Industrial ?40?C ≤T J ≤+85?C
LMC6034IN 14-Pin N14A
Rail
Molded DIP LMC6034IM
14-Pin M14A
Rail Small Outline
Tape and Reel
14-Pin DIP/SO
DS011134-1
Top View
May 1998
LMC6034CMOS Quad Operational Amplifier
?1999National Semiconductor Corporation https://www.wendangku.net/doc/0217517824.html,
Absolute Maximum Ratings(Note1)
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Differential Input Voltage±Supply Voltage Supply Voltage(V+?V?)16V Output Short Circuit to V+(Note10) Output Short Circuit to V?(Note2) Lead Temperature
(Soldering,10sec.)260?C Storage Temperature Range?65?C to+150?C Power Dissipation(Note3) Voltage at Output/Input Pin(V+)+0.3V,(V?)?0.3V Current at Output Pin±18mA Current at Input Pin±5mA Current at Power Supply Pin35mA Junction Temperature(Note3)150?C ESD Tolerance(Note4)1000V
Operating Ratings(Note1)
Temperature Range?40?C≤T J≤+85?C Supply Voltage Range 4.75V to15.5V Power Dissipation(Note11) Thermal Resistance(θJA),(Note12)
14-Pin DIP85?C/W 14-Pin SO115?C/W
DC Electrical Characteristics
Unless otherwise specified,all limits guaranteed for T J=25?C.Boldface limits apply at the temperature extremes.V+=5V, V?=GND=0V,V CM=1.5V,V OUT=2.5V,and R L>1M unless otherwise specified.
Symbol Parameter Conditions Typical
(Note5)LMC6034I Units Limit
(Note6)
V OS Input Offset Voltage19mV
11max ?V OS/?T Input Offset Voltage 2.3μV/?C Average Drift
I B Input Bias Current0.04pA
200max I OS Input Offset Current0.01pA
100max R IN Input Resistance>1Tera?CMRR Common Mode0V≤V CM≤12V8363dB Rejection Ratio V+=15V60min +PSRR Positive Power Supply5V≤V+≤15V8363dB Rejection Ratio V O=2.5V60min ?PSRR Negative Power Supply0V≤V?≤?10V9474dB Rejection Ratio70min V CM Input Common-Mode V+=5V&15V?0.4?0.1V Voltage Range For CMRR≥50dB0max
V+?1.9V+?2.3V
V+?2.6min A V Large Signal Voltage Gain R L=2k?(Note7)2000200V/mV
Sourcing100min
Sinking50090V/mV
40min
R L=600?(Note7)1000100V/mV
Sourcing75min
Sinking25050V/mV
20min https://www.wendangku.net/doc/0217517824.html,2
DC Electrical Characteristics(Continued)
Unless otherwise specified,all limits guaranteed for T J=25?C.Boldface limits apply at the temperature extremes.V+=5V, V?=GND=0V,V CM=1.5V,V OUT=2.5V,and R L>1M unless otherwise specified.
Symbol Parameter Conditions Typical
(Note5)LMC6034I Units Limit
(Note6)
V O Output Voltage Swing V+=5V 4.87 4.20V
R L=2k?to2.5V 4.00min
0.100.25V
0.35max
V+=5V 4.61 4.00V
R L=600?to2.5V 3.80min
0.300.63V
0.75max
V+=15V14.6313.50V
R L=2k?to7.5V13.00min
0.260.45V
0.55max
V+=15V13.9012.50V
R L=600?to7.5V12.00min
0.79 1.45V
1.75max
I O Output Current V+=5V2213mA
Sourcing,V O=0V9min
Sinking,V O=5V2113mA
9min
V+=15V4023mA
Sourcing,V O=0V15min
Sinking,V O=13V3923mA
(Note10)15min
I S Supply Current All Four Amplifiers 1.5 2.7mA
V O=1.5V 3.0max
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AC Electrical Characteristics
Unless otherwise specified,all limits guaranteed for T J=25?C.Boldface limits apply at the temperature extremes.V+=5V, V?=GND=0V,V CM=1.5V,V OUT=2.5V,and R L>1M unless otherwise specified.
Symbol Parameter Conditions Typical
(Note5)LMC6034I Units Limit
(Note6)
SR Slew Rate(Note8) 1.10.8V/μs
0.4min GBW Gain-Bandwidth Product 1.4MHz φM Phase Margin50Deg G M Gain Margin17dB
Amp-to-Amp Isolation(Note9)130dB e
n
Input-Referred Voltage Noise F=1kHz22
Typical Performance Characteristics
V S =±7.5V,T A =25?C unless otherwise specified (Continued)
Applications Hint
Amplifier Topolgy
The topology chosen for the LMC6034,shown in Figure 1,is unconventional (compared to general-purpose op amps)in that the traditional unity-gain buffer output stage is not used;instead,the output is taken directly from the output of the in-tegrator,to allow a larger output swing.Since the buffer tra-ditionally delivers the power to the load,while maintaining high op amp gain and stability,and must withstand shorts to either rail,these tasks now fall to the integrator.
As a result of these demands,the integrator is a compound affair with an embedded gain stage that is doubly fed forward (via C f and Cff)by a dedicated unity-gain compensation driver.In addition,the output portion of the integrator is a push-pull configuration for delivering heavy loads.While sinking current the whole amplifier path consists of three gain stages with one stage fed forward,whereas while sourcing the path contains four gain stages with two fed forward.
Output Characteristics Current Sourcing
DS011134-27
Input Voltage Noise vs Frequency
DS011134-28
CMRR vs Frequency
DS011134-29
Open-Loop Frequency Response DS011134-30Frequency Response vs Capacitive Load DS011134-31
Non-Inverting Large Signal Pulse Response
DS011134-32
Stability vs
Capacitive Load
DS011134-33
Stability vs
Capacitive Load
DS011134-34
Note:Avoid resistive loads of less than 500?,as they may cause instability.
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Applications Hint(Continued)
The large signal voltage gain while sourcing is comparable
to traditional bipolar op amps,even with a600?load.The
gain while sinking is higher than most CMOS op amps,due
to the additional gain stage;however,under heavy load
(600?)the gain will be reduced as indicated in the Electrical
Characteristics.
Compensating Input Capacitance
The high input resistance of the LMC6034op amps allows
the use of large feedback and source resistor values without
losing gain accuracy due to loading.However,the circuit will
be especially sensitive to its layout when these large-value
resistors are used.
Every amplifier has some capacitance between each input
and AC ground,and also some differential capacitance be-
tween the inputs.When the feedback network around an
amplifier is resistive,this input capacitance(along with any
additional capacitance due to circuit board traces,the
socket,etc.)and the feedback resistors create a pole in the
feedback path.In the following General Operational Amplifier
circuit,Figure2the frequency of this pole is
where C S is the total capacitance at the inverting input,in-
cluding amplifier input capcitance and any stray capacitance
from the IC socket(if one is used),circuit board traces,etc.,
and R P is the parallel combination of R F and R IN.This for-
mula,as well as all formulae derived below,apply to invert-
ing and non-inverting op-amp configurations.
When the feedback resistors are smaller than a few k?,the
frequency of the feedback pole will be quite high,since C S is
generally less than10pF.If the frequency of the feedback
pole is much higher than the“ideal”closed-loop bandwidth
(the nominal closed-loop bandwidth in the absence of C S),
the pole will have a negligible effect on stability,as it will add
only a small amount of phase shift.
However,if the feedback pole is less than approximately6to
10times the“ideal”?3dB frequency,a feedback capacitor,
C F,should be connected between the output and the invert-
ing input of the op amp.This condition can also be stated in
terms of the amplifier’s low-frequency noise gain:To main-
tain stability a feedback capacitor will probably be needed if
where
is the amplifier’s low-frequency noise gain and GBW is the
amplifier’s gain bandwidth product.An amplifier’s
low-frequency noise gain is represented by the formula
regardless of whether the amplifier is being used in inverting
or non-inverting mode.Note that a feedback capacitor is
more likely to be needed when the noise gain is low and/or
the feedback resistor is large.
If the above condition is met(indicating a feedback capacitor
will probably be needed),and the noise gain is large enough
that:
the following value of feedback capacitor is recommended:
If
the feedback capacitor should be:
Note that these capacitor values are usually significantly
smaller than those given by the older,more conservative for-
mula:
Using the smaller capacitors will give much higher band-
width with little degradation of transient response.It may be
necessary in any of the above cases to use a somewhat
larger feedback capacitor to allow for unexpected stray ca-
DS011134-3
FIGURE1.LMC6034Circuit Topology(Each Amplifier)
DS011134-4
C S consists of the amplifier’s input capacitance plus any stray capacitance
from the circuit board and socket.C F compensates for the pole caused by
C S and the feedback resistors.
FIGURE2.General Operational Amplifier Circuit https://www.wendangku.net/doc/0217517824.html,6
Applications Hint(Continued)
pacitance,or to tolerate additional phase shifts in the loop,or
excessive capacitive load,or to decrease the noise or band-
width,or simply because the particular circuit implementa-
tion needs more feedback capacitance to be sufficiently
stable.For example,a printed circuit board’s stray capaci-
tance may be larger or smaller than the breadboard’s,so the
actual optimum value for C F may be different from the one
estimated using the breadboard.In most cases,the values
of C F should be checked on the actual circuit,starting with
the computed value.
Capacitive Load Tolerance
Like many other op amps,the LMC6034may oscillate when
its applied load appears capacitive.The threshold of oscilla-
tion varies both with load and circuit gain.The configuration
most sensitive to oscillation is a unity-gain follower.See
Typical Performance Characteristics.
The load capacitance interacts with the op amp’s output re-
sistance to create an additional pole.If this pole frequency is
sufficiently low,it will degrade the op amp’s phase margin so
that the amplifier is no longer stable at low gains.As shown
in Figure3,the addition of a small resistor(50?to100?)in
series with the op amp’s output,and a capacitor(5pF to10
pF)from inverting input to output pins,returns the phase
margin to a safe value without interfering with
lower-frequency circuit operation.Thus larger values of ca-
pacitance can be tolerated without oscillation.Note that in all
cases,the output will ring heavily when the load capacitance
is near the threshold for oscillation.
Capacitive load driving capability is enhanced by using a pull
up resistor to V+(Figure4).Typically a pull up resistor con-
ducting500μA or more will significantly improve capacitive
load responses.The value of the pull up resistor must be de-
termined based on the current sinking capability of the ampli-
fier with respect to the desired output swing.Open loop gain
of the amplifier can also be affected by the pull up resistor
(see Electrical Characteristics).
PRINTED-CIRCUIT-BOARD LAYOUT
FOR HIGH-IMPEDANCE WORK
It is generally recognized that any circuit which must operate
with less than1000pA of leakage current requires special
layout of the PC board.When one wishes to take advantage
of the ultra-low bias current of the LMC6034,typically less
than0.04pA,it is essential to have an excellent layout.For-
tunately,the techniques for obtaining low leakages are quite
simple.First,the user must not ignore the surface leakage of
the PC board,even though it may sometimes appear accept-
ably low,because under conditions of high humidity or dust
or contamination,the surface leakage will be appreciable.
To minimize the effect of any surface leakage,lay out a ring
of foil completely surrounding the LMC6034’s inputs and the
terminals of capacitors,diodes,conductors,resistors,relay
terminals,etc.connected to the op-amp’s inputs.See Figure
5.To have a significant effect,guard rings should be placed
on both the top and bottom of the PC board.This PC foil
must then be connected to a voltage which is at the same
voltage as the amplifier inputs,since no leakage current can
flow between two points at the same potential.For example,
a PC board trace-to-pad resistance of1012?,which is nor-
mally considered a very large resistance,could leak5pA if
the trace were a5V bus adjacent to the pad of an input.This
would cause a100times degradation from the LMC6034’s
actual performance.However,if a guard ring is held within
5mV of the inputs,then even a resistance of1011?would
cause only0.05pA of leakage current,or perhaps a minor
(2:1)degradation of the amplifier’s performance.See Fig-
ures6,7,8for typical connections of guard rings for stan-
dard op-amp configurations.If both inputs are active and at
high impedance,the guard can be tied to ground and still
provide some protection;see Figure9.
DS011134-5
FIGURE3.Rx,Cx Improve Capacitive Load Tolerance
DS011134-22
https://www.wendangku.net/doc/0217517824.html,pensating for Large Capacitive Loads
with a Pull Up Resistor
DS011134-6
FIGURE5.Example of Guard Ring in P.C.Board
Layout
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Applications Hint
(Continued)
The designer should be aware that when it is inappropriate to lay out a PC board for the sake of just a few circuits,there is another technique which is even better than a guard ring on a PC board:Don’t insert the amplifier’s input pin into the
board at all,but bend it up in the air and use only air as an in-sulator.Air is an excellent insulator.In this case you may have to forego some of the advantages of PC board con-struction,but the advantages are sometimes well worth the effort of using point-to-point up-in-the-air wiring.See Figure 10.
BIAS CURRENT TESTING
The test method of Figure 11is appropriate for bench-testing bias current with reasonable accuracy.To understand its op-eration,first close switch S2momentarily.When S2is opened,then
A suitable capacitor for C2would be a 5pF or 10pF silver mica,NPO ceramic,or air-dielectric.When determining the magnitude of I b ?,the leakage of the capacitor and socket must be taken into account.Switch S2should be left shorted most of the time,or else the dielectric absorption of the ca-pacitor C2could cause errors.
Similarly,if S1is shorted momentarily (while leaving S2shorted)
where C x is the stray capacitance at the +input.
DS011134-7
FIGURE 6.Guard Ring Connections
Inverting Amplifier
DS011134-8
FIGURE 7.Guard Ring Connections
Non-Inverting Amplifier
DS011134-9
FIGURE 8.Guard Ring Connections
Follower
DS011134-10
FIGURE 9.Guard Ring Connections
Howland Current Pump
DS011134-11
(Input pins are lifted out of PC board and soldered directly to components.All other pins connected to PC board.)
FIGURE 10.Air Wiring
DS011134-12
FIGURE 11.Simple Input Bias Current Test Circuit https://www.wendangku.net/doc/0217517824.html, 8
Typical Single-Supply Applications
(V +=5.0VDC)
Additional single-supply applications ideas can be found in the LM324datasheet.The LMC6034is pin-for-pin compat-ible with the LM324and offers greater bandwidth and input resistance over the LM324.These features will improve the performance of many existing single-supply applications.Note,however,that the supply voltage range of the LMC6034is smaller than that of the LM324.
For good CMRR over temperature,low drift resistors should be used.Matching of R3to R6and R4to R7affect CMRR.Gain may be adjusted through R2.CMRR may be adjusted through R7.
Oscillator frequency is determined by R1,R2,C1,and C2:fosc =1/2πRC,where R =R1=R2and
C =C1=C2.
This circuit,as shown,oscillates at 2.0kHz with a peak-to-peak output swing of 4.0V.
Low-Leakage Sample-and-Hold
DS011134-13
Instrumentation Amplifier
DS011134-14
Sine-Wave Oscillator
DS011134-15
1Hz Square-Wave Oscillator
DS011134-16
Power Amplifier
DS011134-17
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Typical Single-Supply Applications
(V +=5.0VDC)(Continued)
10Hz Bandpass Filter
DS011134-18
f O =10Hz Q =2.1Gain =?8.8
10Hz High-Pass Filter
DS011134-20
f c =10Hz d =0.895Gain =1
2dB passband ripple
1Hz Low-Pass Filter
(Maximally Flat,Dual Supply Only)
DS011134-19
f c =1Hz d =1.414Gain =1.57
High Gain Amplifier with Offset
Voltage Reduction
DS011134-21
Gain =?46.8Output offset voltage reduced to the level of the input offset voltage of the bottom amplifier (typically 1mV).
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Physical Dimensions inches(millimeters)unless otherwise noted
Small Outline Dual-In-Line Pkg.(M)
Order Number LMC6034IM
NS Package Number M14A
Molded Dual-In-Line Pkg.(N)
Order Number LMC6034IN
NS Package Number N14A
11
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Notes
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L M C 6034C M O S Q u a d O p e r a t i o n a l A m p l i f i e r
National does not assume any responsibility for use of any circuitry described,no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.