LMC6442
Dual Micropower Rail-to-Rail Output Single Supply
Operational Amplifier
General Description
The LMC6442 is ideal for battery powered systems, where
very low supply current (less than one microamp per ampli-
fier) and Rail-to-Rail output swing is required. It is character-
ized for 2.2V to 10V operation, and at 2.2V supply, the
LMC6442 is ideal for single (Li-Ion) or two cell (NiCad or
alkaline) battery systems.
The LMC6442 is designed for battery powered systems that
require long service life through low supply current, such as
smoke and gas detectors, and pager or personal communi-
cations systems.
Operation from single supply is enhanced by the wide com-
mon mode input voltage range which includes the ground (or
negative supply) for ground sensing applications. Very low (5
fA, typical) input bias current and near constant supply cur-
rent over supply voltage enhance the LMC6442’s perfor-
mance near the end-of-life battery voltage.
Designed for closed loop gains of greater than plus two (or
minus one), the amplifier has typically 9.5 KHz GBWP (Gain
Bandwidth Product). Unity gain can be used with a simple
compensation circuit, which also allows capacitive loads of
up to 300 pF to be driven, as described in the Application
Notes section.
Features
(Typical, V
S
= 2.2V)
nOutput Swing to within 30 mV of supply rail
nHigh voltage gain 103 dB
nGain Bandwidth Product 9.5 KHz
nGuaranteed for: 2.2V, 5V, 10V
nLow Supply Current 0.95 µA/Amplifier
nInput Voltage Range −0.3V to V
+
-0.9V
n2.1 µW/Amplifier Power consumption
nStable for A
V
≥+2 or A
V
≤−1
Applications
nPortable instruments
nSmoke/gas/CO/fire detectors
nPagers/cell phones
nInstrumentation
nThermostats
nOccupancy sensors
nCameras
nActive badges
Connection Diagram
10006440
Top View
March 2005
LMC6442 Dual Micropower Rail-to-Rail Output Single Supply Operational Amplifier
© 2005 National Semiconductor Corporation DS100064 www.national.com
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
ESD Tolerance (Note 2) 2 kV
Differential Input Voltage ±Supply Voltages
Voltage at Input/Output Pin (V
+
) + 0.3V, (V
−
) − 0.3V
Supply Voltage (V
+
−V
−
): 16V
Current at Input Pin (Note 10) ±5mA
Current at Output Pin(Notes 3, 7) ±30 mA
Lead Temp. (soldering 10 sec) 260˚C
Storage Temp. Range: −65˚C to +150˚C
Junction Temp. (Note 4) 150˚C
Operating Ratings(Note 1)
Supply Voltage 1.8V ≤V
S
≤11V
Junction Temperature −40˚C <T
J
<+85˚C
Range: LMC6442AI, LMC6442I
Thermal Resistance (θ
JA
)
M Package, 8-pin Surface
Mount
193˚C/W
N Package, 8-pin Molded DIP 115˚C/W
2.2V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
+
= 2.2V, V
−
= 0V, V
CM
=V
O
=V
+
/2, and R
L
=1MΩto V
+
/2.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
LMC6442AI
Limit
(Note 6)
LMC6442I
Limit
(Note 6)
Units
DC Electrical Characteristics
V
OS
Input Offset Voltage −0.75 ±3
±4
±7
±8
mV
max
TCV
OS
Temp. coefficient of
input offset voltage 0.4 µV/˚C
I
B
Input Bias Current (Note 14) 0.005 44
pA
max
I
OS
Input Offset Current (Note 14) 0.0025 22
pA
max
CMRR Common Mode
Rejection Ratio
−0.1V ≤V
CM
≤0.5V 92 67
67
67
67
dB min
C
IN
Common Mode Input
Capacitance
4.7 pF
PSRR Power Supply
Rejection Ratio
V
S
=2.5Vto10V 95 75
75
75
75
dB
min
V
CM
Input Common-Mode
Voltage Range CMRR ≥50 dB
1.3 1.05
0.95
1.05
0.95
V
min
−0.3 −0.2
0
−0.2
0
V
max
A
V
Large Signal Voltage
Gain
Sourcing (Note 11) 100 dB
min
Sinking (Note 11) 94
V
O
= 0.22V to 2V 103 80 80
V
O
Output Swing V
ID
= 100 mV (Note 13) 2.18 2.15
2.15
2.15
2.15
V
min
V
ID
= −100 mV (Note 13) 22 60
60
60
60
mV
max
I
SC
Output Short Circuit
Current
Sourcing, V
ID
= 100 mV
(Notes 12, 13)
50 18
17
18
17 µA
min
Sinking, V
ID
= −100 mV
(Notes 12, 13)
50 20
19
20
19
I
S
Supply Current
(2 amplifiers)
R
L
= open 1.90 2.4
3.0
2.6
3.2 µA
max
V
+
= 1.8V, R
L
= open 2.10
LMC6442
www.national.com 2
2.2V Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
+
= 2.2V, V
−
= 0V, V
CM
=V
O
=V
+
/2, and R
L
=1MΩto V
+
/2.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
LMC6442AI
Limit
(Note 6)
LMC6442I
Limit
(Note 6)
Units
AC Electrical Characteristics
SR Slew Rate (Note 8) 2.2 V/ms
GBWP Gain-Bandwidth
Product
9.5 KHz
φ
m
Phase Margin (Note 15) 63 deg
5V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
+
= 5V, V
−
= 0V, V
CM
=V
O
=V
+
/2, and R
L
=1MΩto V
+
/2.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
LMC6442AI
Limit
(Note 6)
LMC6442I
Limit
(Note 6)
Units
DC Electrical Characteristics
V
OS
Input Offset Voltage −0.75 ±3
±4
±7
±8
mV
max
TCV
OS
Temp. coefficient of
input offset voltage
0.4 µV/˚C
I
B
Input Bias Current (Note 14) 0.005 44
pA
max
I
OS
Input Offset Current (Note 14) 0.0025 22
pA
max
CMRR Common Mode
Rejection Ratio
−0.1V ≤V
CM
≤3.5V 102 70
70
70
70
dB
min
C
IN
Common Mode Input
Capacitance
4.1 pF
PSRR Power Supply
Rejection Ratio
V
S
=2.5Vto10V 95 75
75
75
75
dB
min
V
CM
Input Common-Mode
Voltage Range CMRR ≥50 dB
4.1 3.85
3.75
3.85
3.75
V
min
−0.4 −0.2
0
−0.2
0
V
max
A
V
Large Signal Voltage
Gain
Sourcing (Note 11) 100 dB
min
Sinking (Note 11) 94
V
O
= 0.5V to 4.5V 103 80 80
V
O
Output Swing V
ID
= 100 mV
(Note 13)
4.99 4.95
4.95
4.95
4.95
V
min
V
ID
= −100 mV
(Note 13)
20 50
50
50
50
mV
max
I
SC
Output Short Circuit
Current
Sourcing, V
ID
= 100 mV
(Notes 12, 13)
500 300
200
300
200 µA
min
Sinking, V
ID
= −100 mV
(Notes 12, 13)
350 200
150
200
150
I
S
Supply Current
(2 amplifiers)
R
L
= open 1.90 2.4
3.0
2.6
3.2
µA
max
LMC6442
www.national.com3
5V Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
+
= 5V, V
−
= 0V, V
CM
=V
O
=V
+
/2, and R
L
=1MΩto V
+
/2.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
LMC6442AI
Limit
(Note 6)
LMC6442I
Limit
(Note 6)
Units
AC Electrical Characteristics
SR Slew Rate (Note 8) 4.1 2.5 2.5 V/ms
GBWP Gain-Bandwidth
Product
10 KHz
φ
m
Phase Margin (Note 15) 64 deg
THD Total Harmonic
Distortion
A
V
= +2, f = 100 Hz,
R
L
=10MΩ,V
OUT
=1V
PP
0.08 %
10V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
+
= 10V, V
−
= 0V, V
CM
=V
O
=V
+
/2, and R
L
=1MΩto V
+
/2.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
LMC6442AI
Limit
(Note 6)
LMC6442I
Limit
(Note 6)
Units
DC Electrical Characteristics
V
OS
Input Offset Voltage −1.5 ±3
±4
±7
±8
mV
max
TCV
OS
Temp. coefficient of
input offset voltage
0.4 µV/˚C
I
B
Input Bias Current (Note 14) 0.005 44
pA
max
I
OS
Input Offset Current (Note 14) 0.0025 22
pA
max
CMRR Common Mode
Rejection Ratio
−0.1V ≤V
CM
≤8.5V 105 70
70
70
70
dB
min
C
IN
Common Mode Input
Capacitance
3.5 pF
PSRR Power Supply
Rejection Ratio
V
S
=2.5Vto10V 95 75
75
75
75
dB
min
V
CM
Input Common-Mode
Voltage Range CMRR ≥50 dB
9.1 8.85
8.75
8.85
8.75
V
min
−0.4 −0.2
0
−0.2
0
V
max
A
V
Large Signal Voltage
Gain
Sourcing (Note 11) 120 dB
min
Sinking (Note 11) 100
V
O
= 0.5V to 9.5V 104 80 80
V
O
Output Swing V
ID
= 100 mV
(Note 13)
9.99 9.97
9.97
9.97
9.97
V
min
V
ID
= −100 mV
(Note 13)
22 50
50
50
50
mV
max
I
SC
Output Short Circuit
Current
Sourcing, V
ID
= 100 mV
(Notes 12, 13)
2100 1200
1000
1200
1000 µA
min
Sinking, V
ID
= −100 mV
(Notes 12, 13)
900 600
500
600
500
I
S
Supply Current
(2 amplifiers)
R
L
= open 1.90 2.4
3.0
2.6
3.2
µA
max
LMC6442
www.national.com 4
10V Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
+
= 10V, V
−
= 0V, V
CM
=V
O
=V
+
/2, and R
L
=1MΩto V
+
/2.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
LMC6442AI
Limit
(Note 6)
LMC6442I
Limit
(Note 6)
Units
AC Electrical Characteristics
SR Slew Rate(Note 8) 4.1 2.5 2.5 V/ms
GBWP Gain-Bandwidth
Product
10.5 KHz
φ
m
Phase Margin (Note 15) 68 deg
e
n
Input-Referred
Voltage Noise
R
L
= open
f=10Hz
170 nV/√Hz
i
n
Input-Referred
Current Noise
R
L
= open
f=10Hz
0.0002 pA/√Hz
Crosstalk Rejection (Note 9) 85 dB
Electrical Characteristics (continued)
Note 1: 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 specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics.
Note 2: Human body model, 1.5 kΩin series with 100 pF.
Note 3: Applies to both single-supply and split-supply operation. Continuous short circuit operation at elevated ambient temperature 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 4: 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. All numbers apply for packages soldered directly into a PC board.
Note 5: Typical Values represent the most likely parametric norm.
Note 6: All limits are guaranteed by testing or statistical analysis unless otherwise specified.
Note 7: Do not short circuit output to V+, when V+is greater than 13V or reliability will be adversely affected.
Note 8: Slew rate is the slower of the rising and falling slew rates.
Note 9: Input referred, V+= 10V and RL=10MΩconnected to 5V. Each amp excited in turn with 1 KHz to produce about 10 VPP output.
Note 10: Limiting input pin current is only necessary for input voltages that exceed absolute maximum input voltage ratings.
Note 11: RLconnected to V+/2. For Sourcing Test, VO>V+/2. For Sinking tests, VO<V+/2.
Note 12: Output shorted to ground for sourcing, and shorted to V+ for sinking short circuit current test.
Note 13: VID is differential input voltage referenced to inverting input.
Note 14: Limits guaranteed by design.
Note 15: See the Typical Performance Characteristics and Application Notes sections for more details.
LMC6442
www.national.com5
Typical Performance Characteristics V
S
= 5V, Single Supply, T
A
= 25˚C unless otherwise specified
Total Supply Current vs. Supply Voltage
Total Supply Current vs. Supply Voltage
(Negative Input Overdrive)
10006408 10006409
Total Supply Current vs. Supply Voltage
(Positive Input Overdrive) Input Bias Current vs. Temperature
10006410 10006441
Offset Voltage vs. Common Mode Voltage
(V
S
= 2.2V)
Offset Voltage vs. Common Mode Voltage
(V
S
= 5V)
10006406 10006407
LMC6442
www.national.com 6
Typical Performance Characteristics V
S
= 5V, Single Supply, T
A
= 25˚C unless otherwise
specified (Continued)
Offset Voltage vs. Common Mode Voltage
(V
S
= 10V) Swing Towards V
−
vs. Supply Voltage
10006442 10006403
Swing Towards V
+
vs. Supply Voltage Swing From Rail(s) vs. Temperature
10006402 10006401
Output Source Current vs. Output Voltage Output Sink Current vs. Output Voltage
10006449 10006448
LMC6442
www.national.com7
Typical Performance Characteristics V
S
= 5V, Single Supply, T
A
= 25˚C unless otherwise
specified (Continued)
Maximum Output Voltage vs. Load Resistance Large Signal Voltage Gain vs. Supply Voltage
10006424 10006452
Open Loop Gain/Phase vs. Frequency
Open Loop Gain/Phase vs. Frequency For Various C
L
(Z
L
=1MΩII C
L
)
10006419 10006426
Open Loop Gain/Phase vs. Frequency For Various C
L
(Z
L
= 100 KΩII C
L
) Gain Bandwidth Product vs. Supply Voltage
10006425 10006421
LMC6442
www.national.com 8
Typical Performance Characteristics V
S
= 5V, Single Supply, T
A
= 25˚C unless otherwise
specified (Continued)
Phase Margin (Worst Case) vs. Supply Voltage CMRR vs. Frequency
10006423 10006434
PSRR vs. Frequency Positive Slew Rate vs. Supply Voltage
10006415 10006412
Negative Slew Rate vs. Supply Voltage Cross-Talk Rejection vs. Frequency
10006411 10006418
LMC6442
www.national.com9
Typical Performance Characteristics V
S
= 5V, Single Supply, T
A
= 25˚C unless otherwise
specified (Continued)
Input Voltage Noise vs. Frequency Output Impedance vs. Frequency
10006416 10006433
THD+N vs. Frequency THD+N vs. Amplitude
10006428 10006427
Maximum Output Swing vs. Frequency
Small Signal Step Response
(A
V
= +2) (C
L
= 12 pF, 100 pF)
10006453
10006429
LMC6442
www.national.com 10
Typical Performance Characteristics V
S
= 5V, Single Supply, T
A
= 25˚C unless otherwise
specified (Continued)
Large Signal Step Response
(A
V
= +2) (C
L
= 100 pF)
Small Signal Step Response
(A
V
= −1) (C
L
=1MΩII 100 pF, 200 pF)
10006430 10006451
Small Signal Step Response
(A
V
= +1) For Various C
L
Large Signal Step Response
(A
V
= +1) (C
L
= 200 pF)
10006431 10006432
LMC6442
www.national.com11
Applications Information
USING LMC6442 IN UNITY GAIN APPLICATIONS
LMC6442 is optimized for maximum bandwidth and minimal
external components when operating at a minimum closed
loop gain of +2 (or −1). However, it is also possible to
operate the device in a unity gain configuration by adding
external compensation as shown in Figure 1:
Using this compensation technique it is possible to drive
capacitive loads of up to 300 pF without causing oscillations
(see the Typical Performance Characteristics for step re-
sponse plots). This compensation can also be used with
other gain settings in order to improve stability, especially
when driving capacitive loads (for optimum performance, R
C
and C
C
may need to be adjusted).
USING “T” NETWORK
Compromises need to be made whenever high gain invert-
ing stages need to achieve a high input impedance as well.
This is especially important in low current applications which
tend to deal with high resistance values. Using a traditional
inverting amplifier, gain is inversely proportional to the resis-
tor value tied between the inverting terminal and input while
the input impedance is equal to this value. For example, in
order to build an inverting amplifier with an input impedance
of 10MΩand a gain of 100, one needs to come up with a
feedback resistor of 1000 MΩ-an expensive task.
An alternate solution is to use a “T” Network in the feedback
path, as shown in Figure 2.
Closed loop gain, A
V
is given by:
It must be noted, however, that using this scheme, the
realizable bandwidth would be less than the theoretical
maximum. With feedback factor, β, defined as:
BW(−3 dB) ≈GBWP •β
In this case, assuming a GBWP of about 10 KHz, the ex-
pected BW would be around 50 Hz (vs. 100 Hz with the
conventional inverting amplifier).
Looking at the problem from a different view, with R
F
defined
by A
V
•Rin, one could select a value for R in the “T” Network
and then determine R1 based on this selection:
For convenience, Figure 3 shows R1 vs. R
F
for different
values of R.
DESIGN CONSIDERATIONS FOR CAPACITIVE LOADS
As with many other opamps, the LMC6442 is more stable at
higher closed loop gains when driving a capacitive load.
Figure 4 shows minimum closed loop gain versus load ca-
pacitance, to achieve less than 10% overshoot in the output
small signal response. In addition, the LMC6442 is more
stable when it provides more output current to the load and
when its output voltage does not swing close to V
−
.
The LMC6442 is more tolerant to capacitive loads when the
equivalent output load resistance is lowered or when output
voltage is 1V or greater from the V
−
supply. The capacitive
load drive capability is also improved by adding an isolating
resistor in series with the load and the output of the device.
Figure 5 shows the value of this resistor for various capaci-
tive loads (A
V
= −1), while limiting the output to less than 10
% overshoot.
Referring to the Typical Performance Characteristics plot of
Phase Margin (Worst Case) vs. Supply Voltage, note that
Phase Margin increases as the equivalent output load resis-
tance is lowered. This plot shows the expected Phase Mar-
gin when the device output is very close to V
−
, which is the
least stable condition of operation. Comparing this Phase
Margin value to the one read off the Open Loop Gain/Phase
vs. Frequency plot, one can predict the improvement in
10006435
FIGURE 1. A
V
= +1 Operation by adding C
C
and R
C
10006436
FIGURE 2. “T” Network Used to Replace High Value
Resistor
10006422
FIGURE 3. “T” Network Values for Various Values of R
LMC6442
www.national.com 12
Applications Information (Continued)
Phase Margin if the output does not swing close to V
−
. This
dependence of Phase Margin on output voltage is minimized
as long as the output load, R
L
, is about 1MΩor less.
Output Phase Reversal: The LMC6442 is immune against
this behavior even when the input voltages exceed the com-
mon mode voltage range.
Output Time Delay: Due to the ultra low power consump-
tion of the device, there could be as long as 2.5 ms of time
delay from when power is applied to when the device output
reaches its final value.
10006447
FIGURE 4. Minimum Operating Gain vs. Capacitive Load
10006443
FIGURE 5. Isolating Resistor Value vs Capacitive Load
LMC6442
www.national.com13
Application Circuits
Micropower Single Supply Voltage to Frequency Converter
10006445
V+= 5V: IS<10 µA, f/VC= 4.3 (Hz/V)
10006446
Gain Stage with Current Boosting
10006454
LMC6442
www.national.com 14
Application Circuits (Continued)
Offset Nulling Schemes
10006444
Ordering Information
Package
Temperature Range
Package Marking Transport Media
NSC
Drawing
Industrial
−40˚C to +85˚C
Military
−55˚C to +125˚C
8-Pin SOIC
LMC6442AIM — LMC6442AIM Rails
M08A
LMC6442AIMX 2.5k Tape and Reel
LMC6442IM — LMC6442IM Rails
LMC6442IMX 2.5k Tape and Reel
8-Pin DIP LMC6442IN — LMC6442IN Rails N08E
8-Pin CDIP — 5962-9761301QPA LMC6442AMJ-QML
5962-9761301QPA Rails J08A
10-Pin SOIC — 5962-9761301QXA LMC6442AMWG-Q
9761301QXA Trays WG10A
LMC6442
www.national.com15
Physical Dimensions inches (millimeters)
unless otherwise noted
8-Lead (0.150" Wide) Molded Small Outline Package, JEDEC
NS Package Number M08A
8-Lead (0.300" Wide) Molded Dual-In-Line Package
NS Package Number N08E
LMC6442
www.national.com 16
Notes
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 manufactures products and uses packing materials that 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
LMC6442 Dual Micropower Rail-to-Rail Output Single Supply Operational Amplifier
