LMC660AIMEP - National Semiconductor

LMC660EP

CMOS Quad Operational Amplifier

General Description

The LMC660EP CMOS Quad operational amplifier is ideal

for operation from a single supply. It operates from +5V to

+15V and features rail-to-rail output swing in addition to an

input common-mode range that includes ground. Perfor-

mance limitations that have plagued CMOS amplifiers in the

past are not a problem with this design. Input V

, drift, and

broadband noise as well as voltage gain into realistic loads

(2 kΩand 600Ω) are all equal to or better than widely

accepted bipolar equivalents.

This chip is built with National’s advanced Double-Poly

Silicon-Gate CMOS process.

See the LMC662 datasheet for a dual CMOS operational

amplifier with these same features.

ENHANCED PLASTIC

•Extended Temperature Performance of −40˚C to +85˚C

•Baseline Control - Single Fab & Assembly Site

•Process Change Notification (PCN)

•Qualification & Reliability Data

•Solder (PbSn) Lead Finish is standard

•Enhanced Diminishing Manufacturing Sources (DMS)

Support

Features

nRail-to-rail output swing

nSpecified for 2 kΩand 600Ωloads

nHigh voltage gain: 126 dB

nLow input offset voltage: 3 mV

nLow offset voltage drift: 1.3 µV/˚C

nUltra low input bias current: 2 fA

nInput common-mode range includes V

−

nOperating range from +5V to +15V supply

= 375 µA/amplifier; independent of V

nLow distortion: 0.01% at 10 kHz

nSlew rate: 1.1 V/µs

Applications

nHigh-impedance buffer or preamplifier

nPrecision current-to-voltage converter

nLong-term integrator

nSample-and-Hold circuit

nSelected Military Applications

nSelected Avionics Applications

Ordering Information

PART NUMBER VID PART NUMBER NS PACKAGE NUMBER (Note 3)

LMC660AIMEP V62/04749-01 M14A

(Notes 1, 2) TBD TBD

Note 1: For the following (Enhanced Plastic) version, check for availability: LMC660AIMXEP, LMC660AINEP. Parts listed with an "X" are provided in

Tape & Reel and parts without an "X" are in Rails.

Note 2: FOR ADDITIONAL ORDERING AND PRODUCT INFORMATION, PLEASE VISIT THE ENHANCED PLASTIC WEB SITE AT: www.national.com/

mil

Note 3: Refer to package details under Physical Dimensions

December 2004

LMC660EP CMOS Quad Operational Amplifier

Connection Diagram

14-Pin DIP/SO

20114501

LMC660EP Circuit Topology (Each Amplifier)

20114504

LMC660AEP

www.national.com 2

Absolute Maximum Ratings (Note 6)

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 16V

Output Short Circuit to V

(Note 14)

Output Short Circuit to V

−

(Note 4)

Lead Temperature

(Soldering, 10 sec.) 260˚C

Storage Temp. Range −65˚C to +150˚C

Voltage at Input/Output Pins (V

) + 0.3V, (V

−

) − 0.3V

Current at Output Pin ±18 mA

Current at Input Pin ±5mA

Current at Power Supply Pin 35 mA

Power Dissipation (Note 5)

Junction Temperature 150˚C

ESD tolerance (Note 11) 1000V

Operating Ratings

Temperature Range

LMC660EP −40˚C ≤T

≤+85˚C

Supply Voltage Range 4.75V to 15.5V

Power Dissipation (Note 12)

Thermal Resistance (θ

) (Note 13)

14-Pin Molded DIP 85˚C/W

14-Pin SO 115˚C/W

DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for T

= 25˚C. Boldface

limits apply at the temperature extremes. V

= 5V, V

−

= 0V, V

= 1.5V, V

= 2.5V and R

>1M unless otherwise specified.

(Note 15)

Parameter Conditions Typ

(Note

Limit

(Note 7)

Units

Input Offset

Voltage 13

3.3 max

Input Offset

Voltage 1.3 µV/˚C

Average Drift

Input Bias Current 0.002 pA

4max

Input Offset Current 0.001 pA

2max

Input Resistance >1 TeraΩ

Common Mode 0V ≤V

≤

12.0V 83 70 dB

Rejection Ratio V

= 15V 68 min

Positive Power

Supply

5V ≤V

≤15V 83 70 dB

Rejection Ratio V

= 2.5V 68 min

Negative Power

Supply

0V ≤V

−

≤−10V 94 84 dB

Rejection Ratio 83 min

Input

Common-Mode

=5V&15V −0.4 −0.1 V

Voltage Range For CMRR ≥50

0max

−

1.9

− 2.3 V

− 2.5 min

Large Signal R

=2kΩ(Note

8) 2000 440 V/mV

Voltage Gain Sourcing 400 min

Sinking 500 180 V/mV

120 min

LMC660AEP

www.national.com3

DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for T

= 25˚C. Boldface

limits apply at the temperature extremes. V

= 5V, V

−

= 0V, V

= 1.5V, V

= 2.5V and R

>1M unless otherwise specified.

(Note 15) (Continued)

Parameter Conditions Typ

(Note

Limit

(Note 7)

Units

= 600Ω(Note

8) 1000 220 V/mV

Sourcing 200 min

Sinking 250 100 V/mV

60 min

Output Swing V

= 5V 4.87 4.82 V

=2kΩto

4.79 min

0.10 0.15 V

0.17 max

= 5V 4.61 4.41 V

= 600Ωto

4.31 min

0.30 0.50 V

0.56 max

= 15V 14.63 14.50 V

=2kΩto

14.44 min

0.26 0.35 V

0.40 max

= 15V 13.90 13.35 V

= 600Ωto

13.15 min

0.79 1.16 V

1.32 max

Output Current Sourcing, V

0V 22 16 mA

=5V 14 min

Sinking, V

=5V 21 16 mA

14 min

Output Current Sourcing, V

0V 40 28 mA

= 15V 25 min

Sinking, V

13V 39 28 mA

(Note 14) 24 min

Supply Current All Four

Amplifiers 1.5 2.2 mA

= 1.5V 2.6 max

LMC660AEP

www.national.com 4

AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for T

= 25˚C. Boldface

limits apply at the temperature extremes. V

= 5V, V

−

= 0V, V

= 1.5V, V

= 2.5V and R

>1M unless otherwise specified.

(Note 15)

Parameter Conditions Typ

(Note

Limit

(Note 7)

Units

Slew Rate (Note 9) 1.1 0.8 V/µs

0.6 min

Gain-Bandwidth

Product

1.4 MHz

Phase Margin 50 Deg

Gain Margin 17 dB

Amp-to-Amp

Isolation

(Note 10) 130 dB

Input Referred

Voltage Noise

F = 1 kHz 22

Input Referred

Current Noise

F = 1 kHz 0.0002

Total Harmonic

Distortion

F = 10 kHz, A

−10

=2kΩ,V

= 15V

0.01 %

Note 4: Applies to both single supply and split supply operation. Continuous short circuit operation at elevated ambient temperature and/or multiple Op Amp shorts

can result in exceeding the maximum allowed junction temperature of 150˚C. Output currents in excess of ±30 mA over long term may adversely affect reliability.

Note 5: The maximum power dissipation is a function of TJ(max),θJA, and TA. The maximum allowable power dissipation at any ambient temperature is PD=(T

J(max)

−T

A)/θJA.

Note 6: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is

intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The

guaranteed specifications apply only for the test conditions listed.

Note 7: Typical values represent the most likely parametric norm. Limits are guaranteed by testing or correlation.

Note 8: V+= 15V, VCM = 7.5V and RLconnected to 7.5V. For Sourcing tests, 7.5V ≤VO≤11.5V. For Sinking tests, 2.5V ≤VO≤7.5V.

Note 9: V+= 15V. Connected as Voltage Follower with 10V step input. Number specified is the slower of the positive and negative slew rates.

Note 10: Input referred. V+= 15V and RL=10kΩconnected to V+/2. Each amp excited in turn with 1 kHz to produce VO=13V

PP.

Note 11: Human body model, 1.5 kΩin series with 100 pF.

Note 12: For operating at elevated temperatures the device must be derated based on the thermal resistance θJA with PD=(T

J−T

A)/θJA.

Note 13: All numbers apply for packages soldered directly into a PC board.

Note 14: Do not connect output to V+when V+is greater than 13V or reliability may be adversely affected.

Note 15: "Testing and other quality control techniques are used to the extent deemed necessary to ensure product performance over the specified temperature

range. Product may not necessarily be tested across the full temperature range and all parameters may not necessarily be tested. In the absence of specific

PARAMETRIC testing, product performance is assured by characterization and/or design."

LMC660AEP

www.national.com5

Typical Performance Characteristics

=±7.5V, T

= 25˚C unless otherwise specified

Supply Current

vs Supply Voltage Offset Voltage

20114524 20114525

Input Bias Current

Output Characteristics

Current Sinking

20114526 20114527

Output Characteristics

Current Sourcing

Input Voltage Noise

vs Frequency

20114528 20114529

LMC660AEP

www.national.com 6

Typical Performance Characteristics V

=±7.5V, T

= 25˚C unless otherwise specified (Continued)

CMRR vs Frequency

Open-Loop Frequency

Response

20114530 20114531

Frequency Response

vs Capacitive Load

Non-Inverting Large Signal

Pulse Response

20114532 20114533

Stability vs

Capacitive Load

Stability vs

Capacitive Load

20114534 20114535

Note: Avoid resistive loads of less than 500Ω, as they may cause instability.

Application Hints

AMPLIFIER TOPOLOGY

The topology chosen for the LMC660EP, 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 integrator, to allow rail-to-rail output swing. Since the

buffer traditionally delivers the power to the load, while main-

taining high op amp gain and stability, and must withstand

shorts to either rail, these tasks now fall to the integrator.

LMC660AEP

www.national.com7

Application Hints (Continued)

As a result of these demands, the integrator is a compound

affair with an embedded gain stage that is doubly fed forward

(via C

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.

The large signal voltage gain while sourcing is comparable

to traditional bipolar op amps, even with a 600Ωload. The

gain while sinking is higher than most CMOS op amps, due

to the additional gain stage; however, under heavy load

(600Ω) the gain will be reduced as indicated in the Electrical

Characteristics.

COMPENSATING INPUT CAPACITANCE

The high input resistance of the LMC660EP op 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, the frequency of this pole is Figure 2

where C

is the total capacitance at the inverting input,

including amplifier input capcitance and any stray capaci-

tance from the IC socket (if one is used), circuit board traces,

etc., and R

is the parallel combination of R

and R

. This

formula, as well as all formulae derived below, apply to

inverting and non-inverting op-amp configurations.

When the feedback resistors are smaller than a few kΩ, the

frequency of the feedback pole will be quite high, since C

generally less than 10 pF. 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

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 approximately 6 to

10 times the “ideal” −3 dB frequency, a feedback capacitor,

, 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:

the feedback capacitor should be:

Note that these capacitor values are usually significant

smaller than those given by the older, more conservative

formula:

20114504

FIGURE 1. LMC660EP Circuit Topology (Each

Amplifier)

LMC660AEP

www.national.com 8

Application Hints (Continued)

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-

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

may be different from the one

estimated using the breadboard. In most cases, the values

of C

should be checked on the actual circuit, starting with

the computed value.

CAPACITIVE LOAD TOLERANCE

Like many other op amps, the LMC660EP may oscillate

when its applied load appears capacitive. The threshold of

oscillation varies both with load and circuit gain. The con-

figuration most sensitive to oscillation is a unity-gain follower.

See Typical Performance Characteristics.

The load capacitance interacts with the op amp’s output

resistance 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 Figure 3, the addition of a small resistor (50Ωto

100Ω) in series with the op amp’s output, and a capacitor (5

pF to 10 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 capaci-

tance 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

(Figure 4). Typically a pull up resistor

conducting 500 µA or more will significantly improve capaci-

tive load responses. The value of the pull up resistor must be

determined based on the current sinking capability of the

amplifier 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 than 1000 pA of leakage current requires special

layout of the PC board. When one wishes to take advantage

of the ultra-low bias current of the LMC662, typically less

than 0.04 pA, it is essential to have an excellent layout.

Fortunately, 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 acceptably 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 LMC660EP’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 of 10

Ω, which is nor-

mally considered a very large resistance, could leak 5 pA if

the trace were a 5V bus adjacent to the pad of an input. This

would cause a 100 times degradation from the LMC660EP’s

actual performance. However, if a guard ring is held within

5 mV of the inputs, then even a resistance of 10

Ωwould

20114506

CSconsists of the amplifier’s input capacitance plus any stray capacitance

from the circuit board and socket. CFcompensates for the pole caused by

CSand the feedback resistors.

FIGURE 2. General Operational Amplifier Circuit

20114505

FIGURE 3. Rx, Cx Improve Capacitive Load Tolerance

20114523

FIGURE 4. Compensating for Large Capacitive Loads

with a Pull Up Resistor

LMC660AEP

www.national.com9

Application Hints (Continued)

cause only 0.05 pA of leakage current, or perhaps a minor

(2:1) degradation of the amplifier’s performance. See Figure

6a,Figure 6b,Figure 6c for typical connections of guard

rings for standard 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 Figure 6d.

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

insulator. 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

20114516

FIGURE 5. Example, using the LMC660AIMEP,

of Guard Ring in P.C. Board Layout

20114517

(a) Inverting Amplifier

20114518

(b) Non-Inverting Amplifier

20114519

20114520

(d) Howland Current Pump

FIGURE 6. Guard Ring Connections

LMC660AEP

www.national.com 10

Application Hints (Continued)

Bias Current Testing

The test method of Figure 8 is appropriate for bench-testing

bias current with reasonable accuracy. To understand its

operation, first close switch S2 momentarily. When S2 is

opened, then

A suitable capacitor for C2 would bea5pFor10pFsilver

mica, NPO ceramic, or air-dielectric. When determining the

magnitude of I

−, the leakage of the capacitor and socket

must be taken into account. Switch S2 should be left shorted

most of the time, or else the dielectric absorption of the

capacitor C2 could cause errors.

Similarly, if S1 is shorted momentarily (while leaving S2

shorted)

where C

is the stray capacitance at the + input.

20114521

(Input pins are lifted out of PC board and soldered directly to components.

All other pins connected to PC board.)

FIGURE 7. Air Wiring

20114522

FIGURE 8. Simple Input Bias Current Test Circuit

LMC660AEP

www.national.com11

Typical Single-Supply Applications

= 5.0 VDC)

Additional single-supply applications ideas can be found in

the LM324 datasheet. The LMC660EP is pin-for-pin compat-

ible with the LM324 and 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

LMC660EP is smaller than that of the LM324.

Low-Leakage Sample-and-Hold

20114507

Instrumentation Amplifier

20114508

If R1 = R5, R3 = R6, and R4 = R7; then

∴A

≈100 for circuit shown.

For good CMRR over temperature, low drift resistors should

be used. Matching of R3 to R6 and R4 to R7 affect CMRR.

Gain may be adjusted through R2. CMRR may be adjusted

through R7.

Sine-Wave Oscillator

20114509

Oscillator frequency is determined by R1, R2, C1, and C2:

fosc = 1/2πRC, where R = R1 = R2 and

C=C1=C2.

This circuit, as shown, oscillates at 2.0 kHz with a peak-to-

peak output swing of 4.5V.

LMC660AEP

www.national.com 12

Typical Single-Supply Applications

(V+= 5.0 VDC) (Continued)

1 Hz Square-Wave Oscillator

20114510

Power Amplifier

20114511

10 Hz Bandpass Filter

20114512

fO=10Hz

Q = 2.1

Gain = −8.8

10 Hz High-Pass Filter

20114513

fc=10Hz

d = 0.895

Gain = 1

2 dB passband ripple

1 Hz Low-Pass Filter

(Maximally Flat, Dual Supply Only)

20114514

fc=1Hz

d = 1.414

Gain = 1.57

High Gain Amplifier with Offset

Voltage Reduction

20114515

Gain = −46.8

Output offset voltage reduced to the level of the input offset voltage of the

bottom amplifier (typically 1 mV).

LMC660AEP

www.national.com13

Physical Dimensions inches (millimeters)

unless otherwise noted

Small Outline Dual-In-Line Pkg. (M)

NS Package Number M14A

LMC660AEP

www.national.com 14

Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

Molded Dual-In-Line Pkg. (N)

NS Package Number N14A

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.

For the most current product information visit us at www.national.com.

LIFE SUPPORT POLICY

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS

WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR

CORPORATION. As used herein:

1. Life support devices or systems are devices or systems

which, (a) are intended for surgical implant into the body, or

(b) support or sustain life, and whose failure to perform when

properly used in accordance with instructions for use

provided in the labeling, can be reasonably expected to result

in a significant injury to the user.

2. A critical component is any component of a life support

device or system whose failure to perform can be reasonably

expected to cause the failure of the life support device or

system, or to affect its safety or effectiveness.

BANNED SUBSTANCE COMPLIANCE

National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship

Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned

Substances’’ as defined in CSP-9-111S2.

National Semiconductor

Americas Customer

Support Center

Email: new.feedback@nsc.com

Tel: 1-800-272-9959

National Semiconductor

Europe Customer Support Center

Fax: +49 (0) 180-530 85 86

Email: europe.support@nsc.com

Deutsch Tel: +49 (0) 69 9508 6208

English Tel: +44 (0) 870 24 0 2171

Français Tel: +33 (0) 1 41 91 8790

National Semiconductor

Asia Pacific Customer

Support Center

Email: ap.support@nsc.com

National Semiconductor

Japan Customer Support Center

Fax: 81-3-5639-7507

Email: jpn.feedback@nsc.com

Tel: 81-3-5639-7560

www.national.com

LMC660EP CMOS Quad Operational Amplifier