1
LT2078/LT2079
20789fa
Micropower, Dual and
Quad, Single Supply,
Precision Op Amps
FEATURES
Supply Current per Amplifier: 50µA Max
Offset Voltage: 70µV Max
Offset Current: 250pA Max
Voltage Noise: 0.6µV
P-P
, 0.1Hz to 10Hz
Current Noise: 3pA
P-P
, 0.1Hz to 10Hz
Offset Voltage Drift: 0.4µV/°C
Gain Bandwidth Product: 200kHz
Slew Rate: 0.07V/µs
Single Supply Operation
Input Voltage Range Includes Ground
Output Swings to Ground while Sinking Current
No Pull-Down Resistors Needed
Output Sources and Sinks 5mA Load Current
SO Package with Standard Pinout
DESCRIPTION
U
The LT
®
2078 is a micropower dual op amp in 8-pin small
outline, standard surface mount package, and LT2079 is
a micropower quad op amp offered in the standard 14-pin
surface mount package. Both devices are optimized for
single supply operation at 5V. ±15V specifications are also
provided.
Micropower performance of competing devices is achieved
at the expense of seriously degrading precision, noise,
speed and output drive specifications. The design effort of
the LT2078/LT2079 was concentrated on reducing sup-
ply current without sacrificing other parameters. The
offset voltage achieved is the lowest on any dual or quad
nonchopper stabilized op amp––micropower or other-
wise. Offset current, voltage and current noise, slew rate
and gain bandwidth product are all two to ten times better
than on previous micropower op amps.
Both the LT2078/LT2079 can be operated from a single
supply (as low as one lithium cell or two NiCd batteries).
The input range goes below ground. The all NPN output
stage swings to within a few millivolts of ground while
sinking current––no power consuming pull-down resis-
tors are needed. For applications requiring DIP packages
refer to the LT1078/LT1079.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Battery or Solar-Powered Systems
Portable Instrumentation
Remote Sensor Amplifier
Satellite Circuitry
Micropower Sample-and-Hold
Thermocouple Amplifier
Micropower Filters
TYPICAL APPLICATION
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Single Battery, Micropower, Gain = 100, Instrumentation Amplifier Distribution of Input Offset Voltage
INPUT OFFSET VOLTAGE (µV)
120
NUMBER OF OP AMPS
080
2078/79 • TA02
80 40 40
800
700
600
500
400
300
200
100
0120
V
S
= 5V, 0V
5000 OP AMPS
+
+
INVERTING
–INPUT
1M 2
3
16
5
7
A
1/2 LT2078
10.1k 1M
10.1k
NONINVERTING
+INPUT
B
1/2 LT2078
4
8
3V
(Li-Ion)
OUT
TYPICAL PERFORMANCE
INPUT OFFSET VOLTAGE = 40µV
INPUT OFFSET CURRENT = 0.2nA
TOTAL POWER DISSIPATION = 240µW
COMMON MODE REJECTION = 110dB (AMPLIFIER LIMITED)
GAIN BANDWIDTH PRODUCT = 200kHz
OUTPUT NOISE = 85µV
P-P
0.1Hz TO 10Hz
= 300µV
RMS
OVER FULL BANDWIDTH
INPUT RANGE = 0.03V TO 1.8V
OUTPUT RANGE = 0.03V TO 2.3V
(0.3mV V
IN+
– V
IN
23mV)
OUTPUTS SINK CURRENT—NO PULL-DOWN RESISTORS
LT2078/79 • TA01
APPLICATIONS
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APPLICATIO S
U
FEATURES
TYPICAL APPLICATIO
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DESCRIPTIO
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2
LT2078/LT2079
20789fa
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ABSOLUTE MAXIMUM RATINGS
W
WW
U
Supply Voltage ...................................................... ±22V
Differential Input Voltage ....................................... ±30V
Input Voltage ...............Equal to Positive Supply Voltage
............5V Below Negative Supply Voltage
Output Short-Circuit Duration.......................... Indefinite
Specified Temperature Range
Commercial ............................................. 0°C to 70°C
Industrial ............................................ 40°C to 85°C
Storage Temperature Range ................. 65°C to 150°C
Lead Temperature (Soldering, 10 sec)..................300°C
T
JMAX
= 150°C, θ
JA
= 150°C/ W
T
JMAX
= 150°C, θ
JA
= 190°C/W
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, TA = 25°C, unless otherwise noted.
LT2078AC/LT2078AI LT2078C/LT2078I
LT2079AC/LT2079AI LT2079C/LT2079I
SYMBOL PARAMETER CONDITIONS (NOTE 2) MIN TYP MAX MIN TYP MAX UNITS
V
OS
Input Offset Voltage LT2078 30 70 40 120 µV
LT2079 35 110 40 150 µV
V
OS
Long Term Input Offset 0.4 0.5 µV/Mo
Time Voltage Stability
I
OS
Input Offset Current 0.05 0.25 0.05 0.35 nA
I
B
Input Bias Current 6 8 6 10 nA
e
n
Input Noise Voltage 0.1Hz to 10Hz (Note 3) 0.6 1.2 0.6 µV
P-P
Input Noise Voltage Density f
O
= 10Hz (Note 3) 29 45 29 nVHz
f
O
= 1000Hz (Note 3) 28 37 28 nVHz
i
n
Input Noise Current 0.1Hz to 10Hz (Note 3) 2.3 4.0 2.3 pA
P-P
Input Noise Current Density f
O
= 10Hz (Note 3) 0.06 0.10 0.06 pAHz
f
O
= 1000Hz 0.02 0.02 pAHz
Input Resistance (Note 4)
Differential Mode 400 800 300 800 M
Common Mode 6 6 G
Input Voltage Range 3.5 3.8 3.5 3.8 V
0 0.3 0 0.3 V
CMRR Common Mode Rejection Ratio V
CM
= 0V to 3.5V 95 110 92 108 dB
PSRR Power Supply Rejection Ratio V
S
= 2.3V to 12V 100 114 98 114 dB
ELECTRICAL CHARACTERISTICS
ORDER PART
NUMBER
LT2078ACS8
LT2078AIS8
LT2078CS8
LT2078IS8
2078A
2078AI 2078
2078I
PART MARKING
PACKAGE/ORDER INFORMATION
W
UU
ORDER PART
NUMBER
LT2079ACS
LT2079AIS
LT2079CS
LT2079IS
1
2
3
4
8
7
6
5
TOP VIEW
V
+
OUT B
IN B
+IN B
OUT A
IN A
+IN A
V
S8 PACKAGE
8-LEAD PLASTIC SO
A
B
TOP VIEW
S PACKAGE
14-LEAD PLASTIC SO
1
2
3
4
5
6
7
14
13
12
11
10
9
8
OUT A
IN A
+IN A
V
+
+IN B
IN B
OUT B
OUT D
IN D
+IN D
V
+IN C
IN C
OUT C
AD
BC
(Note 1)
3
LT2078/LT2079
20789fa
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, 0°C TA 70°C, unless otherwise noted (Note 7)
LT2078AI/LT2079AI LT2078I/LT2079I
SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
V
OS
Input Offset Voltage LT2078 70 250 95 370 µV
LT2079 80 280 100 400 µV
V
OS
Input Offset Voltage Drift LT2078 0.4 1.8 0.5 2.5 µV/°C
T (Note 6) LT2079 0.6 3.0 0.6 3.5 µV/°C
I
OS
Input Offset Current 0.07 0.70 0.1 1.0 nA
I
B
Input Bias Current 710 712 nA
CMRR Common Mode Rejection Ratio V
CM
= 0.05V to 3.2V 90 106 86 104 dB
PSRR Power Supply Rejection Ratio V
S
= 3.1V to 12V 96 110 92 110 dB
A
VOL
Large-Signal Voltage Gain V
O
= 0.05V to 4V, No Load 110 600 80 600 V/mV
V
O
= 0.05V to 3.5V, R
L
= 50k 80 400 60 400 V/mV
Maximum Output Voltage Output Low, No Load 4.5 8 4.5 8 mV
Swing Output Low, I
SINK
= 100µA125 170 125 170 mV
Output High, No Load 3.9 4.2 3.9 4.2 V
Output High, 2k to GND 3.0 3.7 3.0 3.7 V
I
S
Supply Current per Amplifier 43 60 45 70 µA
ELECTRICAL CHARACTERISTICS
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, TA = 25°C, unless otherwise noted.
LT2078AC/LT2078AI LT2078C/LT2078I
LT2079AC/LT2079AI LT2079C/LT2079I
SYMBOL PARAMETER CONDITIONS (NOTE 1) MIN TYP MAX MIN TYP MAX UNITS
A
VOL
Large-Signal Voltage Gain V
O
= 0.03V to 4V, No Load 200 1000 150 1000 V/mV
V
O
= 0.03V to 3.5V, R
L
= 50k 150 600 120 600 V/mV
Maximum Output Voltage Output Low, No Load 3.5 6 3.5 6 mV
Swing Output Low, 2k to GND 0.55 1.2 0.55 1.2 mV
Output Low, I
SINK
= 100µA 95 130 95 130 mV
Output High, No Load 4.2 4.4 4.2 4.4 V
Output High, 2k to GND 3.5 3.9 3.5 3.9 V
SR Slew Rate A
V
= 1, V
S
= ±2.5V 0.04 0.07 0.04 0.07 V/µs
GBW Gain Bandwidth Product f
O
20kHz 200 200 kHz
I
S
Supply Current per Amplifier 38 50 39 55 µA
Channel Separation V
IN
= 3V, R
L
= 10k, f 10Hz 110 110 dB
Minimum Supply Voltage (Note 5) 2.2 2.3 2.2 2.3 V
LT2078AC/LT2079AC LT2078C/LT2079C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
V
OS
Input Offset Voltage LT2078 50 150 60 240 µV
LT2079 60 180 70 270 µV
V
OS
Input Offset Voltage Drift LT2078 0.4 1.8 0.5 2.5 µV/°C
T (Note 6) LT2079 0.5 3.0 0.6 3.5 µV/°C
I
OS
Input Offset Current 0.06 0.35 0.06 0.50 nA
I
B
Input Bias Current 69 611 nA
CMRR Common Mode Rejection Ratio V
CM
= 0V to 3.4V 92 108 88 106 dB
PSRR Power Supply Rejection Ratio V
S
= 2.6V to 12V 98 112 95 112 dB
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, –40°C TA 85°C for I grades, unless otherwise noted.
4
LT2078/LT2079
20789fa
LT2078AI/LT2079AI LT2078I/LT2079I
SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
V
OS
Input Offset Voltage LT2078 90 430 120 600 µV
LT2079 100 500 130 700 µV
V
OS
Input Offset Voltage Drift LT2078 0.5 1.8 0.6 2.5 µV/°C
T (Note 6) LT2079 0.6 3.0 0.7 3.8 µV/°C
I
OS
Input Offset Current 0.07 0.70 0.1 1.0 nA
I
B
Input Bias Current 710 712 nA
A
VOL
Large-Signal Voltage Gain V
O
= ±10V, R
L
= 5k 200 700 150 700 V/mV
CMRR Common Mode Rejection Ratio V
CM
= 13V, –14.9V 92 110 88 110 dB
PSRR Power Supply Rejection Ratio V
S
= 5V, 0V to ±18V 96 110 92 110 dB
Maximum Output Voltage Swing R
L
= 5k ±11.0 ±13.5 ±11.0 ±13.5 V
I
S
Supply Current per Amplifier 52 80 54 95 µA
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VS = ±15V, –40°C TA 85°C for I grades, unless otherwise noted.
LT2078AC/LT2079AC LT2078C/LT2079C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
A
VOL
Large-Signal Voltage Gain V
O
= 0.05V to 4V, No Load 150 750 110 750 V/mV
V
O
= 0.05V to 3.5V, R
L
= 50k 110 500 80 500 V/mV
Maximum Output Voltage Output Low, No Load 4.0 7 4.0 7 mV
Swing Output Low, I
SINK
= 100µA105 150 105 150 mV
Output High, No Load 4.1 4.3 4.1 4.3 V
Output High, 2k to GND 3.3 3.8 3.3 3.8 V
I
S
Supply Current per Amplifier 40 55 42 63 µA
VS = ±15V, TA = 25°C, unless otherwise noted.
LT2078AC/LT2078AI LT2078C/LT2078I
LT2079AC/LT2079AI LT2079C/LT2079I
SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
V
OS
Input Offset Voltage LT2078 50 250 70 350 µV
LT2079 60 350 80 450 µV
I
OS
Input Offset Current 0.05 0.25 0.05 0.35 nA
I
B
Input Bias Current 6 8 6 10 nA
Input Voltage Range 13.5 13.8 13.5 13.8 V
–15.0 –15.3 –15.0 –15.3 V
CMRR Common Mode Rejection Ratio V
CM
= 13.5V, –15V 98 114 95 114 dB
PSRR Power Supply Rejection Ratio V
S
= 5V, 0V to ±18V 100 114 98 114 dB
A
VOL
Large-Signal Voltage Gain V
O
= ±10V, R
L
= 50k 1000 5000 1000 5000 V/mV
V
O
= ±10V, R
L
= 2k 400 1100 300 1100 V/mV
V
OUT
Maximum Output Voltage R
L
= 50k ±13.0 ±14.0 ±13.0 ±14.0 V
Swing R
L
= 2k ±11.0 ±13.2 ±11.0 ±13.2 V
SR Slew Rate 0.06 0.10 0.06 0.10 V/µs
I
S
Supply Current per Amplifier 46 65 47 75 µA
ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, 0°C TA 70°C, unless otherwise noted.
5
LT2078/LT2079
20789fa
LT2078AC/LT2079AC LT2078C/LT2079C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
V
OS
Input Offset Voltage LT2078 70 330 90 460 µV
LT2079 80 410 100 540 µV
V
OS
Input Offset Voltage Drift LT2078 0.5 1.8 0.6 2.5 µV/°C
T (Note 6) LT2079 0.6 3.0 0.7 3.8 µV/°C
I
OS
Input Offset Current 0.06 0.35 0.06 0.50 nA
I
B
Input Bias Current 69 611 nA
A
VOL
Large-Signal Voltage Gain V
O
= ±10V, R
L
= 5k 300 1200 250 1200 V/mV
CMRR Common Mode Rejection Ratio V
CM
= 13V, –15V 95 112 92 112 dB
PSRR Power Supply Rejection Ratio V
S
= 5V, 0V to ±18V 98 112 95 112 dB
Maximum Output Voltage Swing R
L
= 5k ±11.0 ±13.6 ±11.0 ±13.6 V
I
S
Supply Current per Amplifier 49 73 50 85 µA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: Typical parameters are defined as the 60% yield of parameter
distributions of individual amplifiers, i.e., out of 100 LT2079s (or 100
LT2078s) typically 240 op amps (or 120) will be better than the indicated
specification.
Note 3: This parameter is tested on a sample basis only. All noise
parameters are tested with V
S
= ±2.5V, V
O
= 0V.
Note 4: This parameter is guaranteed by design and is not tested.
Note 5: Power supply rejection ratio is measured at the minimum supply
voltage. The op amps actually work at 1.8V supply but with a typical offset
skew of –300µV.
Note 6: This parameter is not 100% tested.
Note 7: The LT2078C/LT2079C are designed, characterized and expected
to meet the industrial temperature limits, but are not tested at –40°C and
85°C. I-grade parts are guaranteed.
TYPICAL PERFORMANCE CHARACTERISTICS
UW
ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VS = ±15V, 0°C TA 70°C, unless otherwise noted (Note 7).
Input Bias Current vs
Common Mode Voltage
COMMON MODE VOLTAGE (V)
–1
INPUT BIAS CURRENT (nA)
0
–2
–4
–6
–8
–10
–12 0123
LT2078/79 • TPC03
4
T
A
= 125°C
T
A
= –55°C
V
S
= 5V, 0V
T
A
= 25°C
Input Bias and Offset Currents vs
Temperature
TEMPERATURE (°C)
–50
BIAS CURRENT (nA) OFFSET CURRENT (pA)
100
50
0
–5
–6
–7 050 75
LT2078/79 • TPC02
–25 25 100 125
I
OS
I
B
V
S
= 5V, 0V TO ±15V
Distribution of Offset Voltage
Drift with Temperature
OFFSET VOLTAGE DRIFT WITH TEMPERATURE (µV/°C)
PERCENT OF UNITS (%)
25
20
15
10
5
0
LT2078/79 • TPC01
–2 –1 0 1 2
V
S
= 5V, 0V
V
CM
= 0.1V
80 LT2078'S
25 LT2079'S
= 260 OP AMPS
6
LT2078/LT2079
20789fa
TIME (SEC)
0
NOISE VOLTAGE (0.4µV/DIV)
8
LT2078/79 • TPC04
24610
CHANNEL A
CHANNEL B
TA = 25°C
VS = ±2.5V
TYPICAL PERFORMANCE CHARACTERISTICS
UW
Noise Spectrum
0.01Hz to 10Hz Noise
TIME (SEC)
0
NOISE VOLTAGE (0.4µV/DIV)
80
LT2078/79 • TPC05
20 40 60 100
CHANNEL B
T
A
= 25°C
V
S
= ±2.5V
CHANNEL A
0.4µV
FREQUENCY (Hz)
0.1 1 100
10
VOLTAGE NOISE DENSITY (nV/Hz)
CURRENT NOISE DENSITY (fA/Hz)
100
30
1000
300
10 1000
LT2078/79 • TPC06
CURRENT
NOISE
VOLTAGE
NOISE
1/f CORNER
0.7Hz
TA = 25°C
VS = ±2.5V
(AT VS = ±15V
VOLTAGE NOISE
IS 4% LESS
CURRENT NOISE
IS UNCHANGED)
Warm-Up Drift
Long Term Stability of Two
Representative Units (LT2078)10Hz Voltage Noise Distribution
VOLTAGE NOISE DENSITY (nV/Hz)
25
LT2078/79 • TPC07
30 35 40
PERCENT OF UNITS
35
30
25
20
15
10
5
0
T
A
= 25°C
V
S
= ±2.5V
TIME AFTER POWER-ON (MINUTES)
0
CHANGE IN OFFSET VOLTAGE (µV)
LT2078/79 • TPC09
12
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
03
T
A
= 25°C
V
S
= ±15V
WARM UP DRIFT
AT V
S
= 5V, 0V IS
IMMEASURABLY LOW
LT2079
LT2078
TIME (MONTHS)
0
OFFSET VOLTAGE CHANGE (µV)
1234
LT2078/79 • TPC08
5
15
10
5
0
–5
–10
–15
T
A
= 25°C, V
S
= 5V, 0V
V
CM
= 0.1V
1A
2B
1B
2A
Output Voltage Swing vs
Load Current
Output Saturation vs Temperature
vs Sink CurrentMinimum Supply Voltage
POSITIVE SUPPLY VOLTAGE (V)
0
INPUT OFFSET VOLTAGE (µV)
100
0
100
200
300
400
500
LT2078/79 • TPC10
123
V
= 0V
0.1V VCM 0.4V
125°C
–55°C
0°C
25°C
70°C
NONFUNCTIONAL
TEMPERATURE (°C)
–50
SATURATION VOLTAGE (mV)
1000
100
10
125 125
LT2078/79 • TPC11
0 25 50 10075
I
SINK
= 2mA
I
SINK
= 1mA
I
SINK
= 100µA
I
SINK
= 1µA
NO LOAD
R
L
= 5k TO GND
I
SINK
= 10µA
V
S
= 5V, 0V
SOURCING OR SINKING LOAD CURRENT (mA)
0.01
OUTPUT VOLTAGE SWING (V)
V
+
V
+
– 1
V
+
– 2
V
+ 2
V
+ 1
V
10
LT2078/79 • TPC11.5
0.1 1
125°C25°C
–55°C
125°C
–55°C
25°C
0.1Hz to 10Hz Noise
7
LT2078/LT2079
20789fa
TYPICAL PERFORMANCE CHARACTERISTICS
UW
Voltage Gain vs Load Resistance
LOAD RESISTANCE TO GROUND ()
100
100k
VOLTAGE GAIN (V/V)
1M
10M
10k 100k1k 1M
LT2078/79 • TPC14
25°C
–55°C
125°C
25°C
–55°C
125°C
VS = ±15V
VS = 5V, 0V
Capacitive Load Handling
Gain, Phase vs Frequency
FREQUENCY (kHz)
30
30
20
10
0
–10 100 300
LTC2078/79 TPC12
VOLTAGE GAIN (dB)
100
120
140
160
180
200
PHASE SHIFT (DEG)
10 1000
PHASE
MARGIN
58°
PHASE
MARGIN
46°
5V, 0V ±15V
±15V
5V, 0V
Voltage Gain vs Frequency
FREQUENCY (Hz)
0.01
VOLTAGE GAIN (dB)
1M
LT2078/79 • TPC13
1100 10k
140
120
100
80
60
40
20
0
–20 0.1 10 1k 100k
V
S
= ±15V
V
S
= 5V, 0V
T
A
= 25°C
Slew Rate, Gain Bandwidth Product
and Phase Margin vs Temperature
TEMPERATURE (°C)
–50
GAIN BANDWIDTH
PRODUCT (kHz) SLEW RATE (V/µs)
PHASE MARGIN (DEG)
0.12
0.10
0.08
0.06
0.04
240
220
200
180
160
75
65
55
45
050 75
LT2078/79 • TPC15
–25 25 100 125
SLEW = ±15V
GBW = ±15V
GBW = 5V, 0V
SLEW = 5V, 0V
φ
M
= ±15V
φ
M
= 5V, 0V
f
O
= 20kHz
Channel Separation vs Frequency
FREQUENCY (Hz)
1
CHANNEL SEPARATION (dB)
120
100
80
60
40
20
010 100 1k 10k
LT2078/79 • TPC16
100k 1M
T
A
= 25°C
V
S
= ±2.5V
V
IN
= 3V
P-P
R
L
= 10k
CAPACITIVE LOAD (pF)
10
OVERSHOOT (%)
120
100
80
60
40
20
010000
LT2078/79 • TPC17
1000100
T
A
= 25°C
V
S
= 5V, 0V
A
V
= 1
A
V
= 10
A
V
= 5
Power Supply Rejection Ratio
vs Frequency
Undistorted Output Swing
vs Frequency Common Mode Rejection Ratio
vs Frequency
FREQUENCY (Hz)
10
COMMON MODE REJECTION RATIO (dB)
100 1k 10k 100k
LT2078/79 • TPC19
1M
T
A
= 25°C
120
100
80
60
40
20
0
V
S
= ±15V
V
S
= 5V, 0V
FREQUENCY (kHz)
0.01
PEAK-TO-PEAK OUTPUT SWING, V
S
= ±15V (V)
PEAK-TO-PEAK OUTPUT SWING, V
S
= 5V, 0V (V)
30
20
10
0
5
4
3
2
1
0
100
LT2078/79 • TPC18
110
V
S
= 5V, 0V
R
L
100k
V
S
= ±15V
R
L
100k
V
S
= ±15V
R
L
= 30k
V
S
= 5V, 0V
R
L
1k
T
A
= 25°C
LOAD R
L
,
TO GND
FREQUENCY (Hz)
0.1
POWER SUPPLY REJECTION RATIO (dB)
120
100
80
60
40
20
0100 10k
LT2078/79 • TPC20
110 1k 100k 1M
TA = 25°C
VS = ±2.5V + 1VP-P SINE WAVE
POSITIVE
SUPPLY
NEGATIVE
SUPPLY
8
LT2078/LT2079
20789fa
TYPICAL PERFORMANCE CHARACTERISTICS
UW
Supply Current vs Temperature
TEMPERATURE (°C)
–50
SUPPLY CURRENT PER AMPLIFIER (µA)
55
50
45
40
35
30
25 25 75
LT2078/79 • TPC21
–25 0 50 100 125
VS = ±15V
VS = 5V, 0V
Small-Signal Transient Response
VS = 5V, 0V
20mV/DIV
A
V
= 1 10µs/DIV
C
L
= 15pF
INPUT 50mV TO 150mV LT2078/79 • TPC24
0V
Closed-Loop Output Impedance
FREQUENCY (Hz)
OUTPUT IMPEDANCE ()
1k
100
10
1
0.1
LT2078/79 • TPC23
10 100 1k 10k 100k
A
V
= 100
A
V
= 10
A
V
= 1
Small-Signal Transient Response
VS = ±15V
20mV/DIV
A
V
= 1 10µs/DIV
C
L
= 15pF
LT2078/79 • TPC26
0V
Common Mode Range vs
Temperature
TEMPERATURE (°C)
–50
COMMON MODE RANGE (V)
25 0 25 50 75
LT2078/79 • TPC22
125
V
+
V
+
– 1
V
+
– 2
V
+ 1
V
V
– 1 100
V
+
= 2.5V TO 18V
V
= 0V TO –18V
Small-Signal Transient Response
VS = ±2.5V
20mV/DIV
A
V
= 1 10µs/DIV
C
L
= 15pF
LT2078/79 • TPC25
0V
Large-Signal Transient Response
VS = 5V, 0V
1V/DIV
A
V
= 1, NO LOAD 50µs/DIV
INPUT PULSE 0V TO 3.8V
LT2078/79 • TPC27
Large-Signal Transient Response
VS = ±15V
5V/DIV
A
V
= 1 100µs/DIV
NO LOAD
LT2078/79 • TPC28
0V
0V
9
LT2078/LT2079
20789fa
SCHEMATIC
WW
SI PLIFIED
1/2 LT2078, 1/4 LT2079
10k 10k 2.2k 5.6k
Q5 Q6
Q11
600
600
Q1
Q21
Q2
Q22
Q9
C2
175pF
6.2k
Q7
Q28
4
1
Q12
Q3
Q16 Q14
Q29
Q4 Q24
8.6k C1
50pF
C5
2.5pF
Q27
V+
Q10 Q17
Q8
6.2k
Q19
Q18
Q15 Q32
1.3k 3.6k
Q37
Q30
13
Q25
C4
4pF 2.9k
3k
Q31
C3
40pF
Q23
Q20
1.35k 30
Q34
Q36
OUT
Q26
30
Q35
5k
Q54
112
150k
Q33
10k
V+
Q38
5.35k
Q45 Q55
Q51
Q42
Q44
V+
V
Q46
Q47
11.5k
V+
12.5k
Q40
Q41
Q48
9.1k
Q43
V
700k
700k
LT2078/79 • SIMPLIFIED SCHEM
IN
IN+
Q50 Q49
J1
Q39
Q53
Q52
4A
10
LT2078/LT2079
20789fa
APPLICATIONS INFORMATION
WUU U
The LT2078/LT2079 devices are fully specified with
V
+
= 5V, V
= 0V, V
CM
= 0.1V. This set of operating
conditions appears to be the most representative for
battery powered micropower circuits. Offset voltage is
internally trimmed to a minimum value at these supply
voltages. When 9V or 3V batteries or ±2.5V dual supplies
are used, bias and offset current changes will be minimal.
Offset voltage changes will be just a few microvolts as
given by the PSRR and CMRR specifications. For example,
if PSRR = 114dB (=2µV/V), at 9V the offset voltage change
will be 8µV. Similarly, V
S
= ±2.5V, V
CM
= 0V is equivalent
to a common mode voltage change of 2.4V or a V
OS
change of 7µV if CMRR = 110dB (3µV/V).
A full set of specifications is also provided at ±15V supply
voltages for comparison with other devices and for com-
pleteness.
Single Supply Operation
The LT2078/LT2079 is quite tolerant of power supply
bypassing. In some applications requiring faster settling
time the positive supply pin of the LT2078/LT2079 should
be bypassed with a small capacitor (about 0.1µF). The
same is true for the negative supply pin when using split
supplies.
The LT2078/LT2079 are fully specified for single supply
operation, i.e., when the negative supply is 0V. Input
common mode range goes below ground and the output
swings within a few millivolts of ground while sinking
current. All competing micropower op amps either cannot
swing to within 600mV of ground (OP-20, OP-220, OP-
420) or need a pull-down resistor connected to the output
to swing to ground (OP-90, OP-290, OP-490, HA5141/42/
44). This difference is critical because in many applica-
tions these competing devices cannot be operated as
micropower op amps and swing to ground simultaneously.
As an example, consider the instrumentation amplifier
shown on the front page. When the common mode signal
is low and the output is high, amplifier A has to sink
current. When the common mode signal is high and the
output low, amplifier B has to sink current. The competing
devices require a 12k pull-down resistor at the output of
amplifier A and a 15k at the output of B to handle the
specified signals. (The LT2078 does not need pull-down
resistors.) When the common mode input is high and the
output is high these pull-down resistors draw 300µA (150µA
each), which is excessive for micropower applications.
The instrumentation amplifier is by no means the only
application requiring current sinking capability. In seven
of the nine single supply applications shown in this data
sheet the op amps have to be able to sink current. In two
of the applications the first amplifier has to sink only the
6nA input bias current of the second op amp. The compet-
ing devices, however, cannot even sink 6nA without a
pull-down resistor
Since the output of the LT2078/LT2079 cannot go exactly
to ground, but can only approach ground to within a few
millivolts, care should be exercised to ensure that the
output is not saturated. For example, a 1mV input signal
will cause the amplifier to set up in its linear region in the
gain 100 configuration shown in Figure 1, but is not
enough to make the amplifier function properly in the
voltage follower mode.
Single supply operation can also create difficulties at the
input. The driving signal can fall below 0V — inadvertently
or on a transient basis. If the input is more than a few
hundred millivolts below ground, two distinct problems
can occur on previous single supply designs, such as the
LM124, LM158, OP-20, OP-21, OP-220, OP-221, OP-420
(1 and 2), OP-90/290/490 (2 only):
Figure 1a. Gain 100 Amplifier Figure 1b. Voltage Follower
+
5V
1mV
R99R
100mV
LT2078/79 • F02a
+
5V
1mV
OUTPUT
SATURATION
3.5mV
LT2078/79 • F02b
11
LT2078/LT2079
20789fa
APPLICATIONS INFORMATION
WUU U
1. When the input is more than a diode drop below ground,
unlimited current will flow from the substrate (V
terminal) to the input. This can destroy the unit. On the
LT2078/LT2079, resistors in series with the input protect
the devices even when the input is 5V below ground.
2. When the input is more than 400mV below ground (at
25°C), the input stage saturates and phase reversal
occurs at the output. This can cause lockup in servo
systems. Due to a unique phase reversal protection cir-
cuitry, the LT2078/LT2079 output does not reverse, as
illustrated in Figure 2, even when the inputs are at –1V.
Distortion
There are two main contributors of distortion in op amps:
distortion caused by nonlinear common mode rejection
and output crossover distortion as the output transitions
from sourcing to sinking current. The common mode
rejection of the LT2078/LT2079 is very good, typically
108dB. Therefore, as long as the input operates in the
normal common mode range, there will be very little
common mode induced distortion. If the op amp is oper-
ating inverting there is no common mode induced distor-
tion. Crossover distortion will increase as the output load
resistance decreases. For the lowest distortion the LT2078/
LT2079 should be operated with the output always sourc-
ing current, this is usually accomplished by putting a
resistor from the output to V
. In an inverting configura-
tion with no load, the output will source and sink current
through the feedback resistor. High value feedback resis-
tors will reduce crossover distortion and maintain
micropower operation.
Matching Specifications
In many applications the performance of a system de-
pends on the matching between two op amps, rather than
Figure 2. Voltage Follower with Input Exceeding the Negative Common Mode Range (VS = 5V, 0V)
2V
0V
6V
P-P
INPUT 1ms/DIV
–1V TO 5V
LT2078/79 • F01a
1ms/DIV
LT2078/LT2079 NO PHASE REVERSAL
LT2078/79 • F01C
2V
0V
4V
1ms/DIV
OP-90 EXHIBITS OUTPUT PHASE REVERSAL
LT2078/79 • F01b
2V
0V
4V
4V
Table 1
LT2078AC/LT2079AC/LT2078AI/LT2079AI LT2078C/LT2079C/LT2078I/LT2079I
PARAMETER 50% YIELD 98% YIELD 50% YIELD 98% YIELD UNITS
V
OS
Match, V
OS
LT2078 30 110 50 190 µV
LT2079 40 150 50 250 µV
Temperature Coefficient V
OS
0.5 1.2 0.6 1.8 µV/°C
Average Noninverting I
B
68610 nA
Match of Noninverting I
B
0.12 0.4 0.15 0.5 nA
CMRR Match 120 100 117 97 dB
PSRR Match 117 105 117 102 dB
12
LT2078/LT2079
20789fa
APPLICATIONS INFORMATION
WUU U
4
V
S
= 5V, 0V 200µs/DIV
LT2078/79 • F03
2
0
0
–100
INPUT (mV) OUTPUT (V)
Figure 3. Comparator Rise Response
Time to 10mV, 5mV, 2mV Overdrives
V
S
= 5V, 0V 200µs/DIV
LT2078/79 • F04
0
100
0
INPUT (mV) OUTPUT (V)
4
2
Figure 4. Comparator Fall Response
Time to 10mV, 5mV, 2mV Overdrives
the individual characteristics of the two devices, the two
and three op amp instrumentation amplifier configura-
tions shown in this data sheet are examples. Matching
characteristics are not 100% tested on the LT2078/LT2079.
Some specifications are guaranteed by definition. For
example, 70µV maximum offset voltage implies that mis-
match cannot be more than 140µV. 95dB (= 17.5µV/V)
CMRR means that worst-case CMRR match is 89dB
(= 35µV/V). However, Table 1 can be used to estimate the
expected matching performance at V
S
= 5V, 0V between
the two sides of the LT2078, and between amplifiers A and
D, and between amplifiers B and C of the LT2079.
Comparator Applications
The single supply operation of the LT2078/LT2079 and its
ability to swing close to ground while sinking current
lends itself to use as a precision comparator with TTL
compatible output.
TYPICAL APPLICATIONS
U
Micropower, 10ppm/°C, ±5V Reference Gain of 10 Difference Amplifier
+
1M
1M
10M
OUTPUT
0.0035V TO 2.4V
1/2 LT2078
BANDWIDTH= 20kHz
OUTPUT OFFSET= 0.7mV
OUTPUT NOISE= 80µV
P-P
(0.1Hz TO 10Hz)
260µV
RMS
OVER FULL
BANDWIDTH
THE USEFULNESS OF DIFFERENCE AMPLIFIERS IS LIMITED BY THE FACT THAT
THE INPUT RESISTANCE IS EQUAL TO THE SOURCE RESISTANCE. THE PICOAMPERE
OFFSET CURRENT AND LOW CURRENT NOISE OF THE LT2078 ALLOWS THE USE OF
1M SOURCE RESISTORS WITHOUT DEGRADATION IN PERFORMANCE. IN ADDITION,
WITH MEGOHM RESISTORS MICROPOWER OPERATION CAN BE MAINTAINED
LT2078/79 • TA04
–IN
+IN
10M
3V
+
+
2M
220k
120k 3
2
1
8
4
1/2 LT2078
9V
5V
OUT
1M 6
5
7
LT1034BC-1.2
510k
1M
5.000V
OUT
–9V 510k
1%
20k
160k
1%
1/2 LT2078
SUPPLY CURRENT = 9V BATTERY = 115µA
9V BATTERY = 85µA
OUTPUT NOISE = 36µV
P-P
, 0.1Hz TO 10Hz
THE LT2078 CONTRIBUTES LESS THAN 3% OF THE TOTAL OUTPUT NOISE AND
DRIFT WITH TIME AND TEMPERATURE. THE ACCURACY OF THE –5V OUTPUT
DEPENDS ON THE MATCHING OF THE TWO 1M RESISTORS
LT2078/79 • TA03
13
LT2078/LT2079
20789fa
TYPICAL APPLICATIONS
U
+
9
10
8
1/4 LT2079
+
+
+
R2
1M
R2
1M
1/4 LT2079
1/4 LT2079
1/4 LT2079
3
2
1
R1
1M
R1
1M
R
G
200k
6
5
7
12
13
14
R3
9.1M
R3
9.1M
9V
4
11
2R
20M
OUTPUT
4mV TO 8.2V
R
10M
2R
20M
–IN
+IN
GAIN = 1 +
()
2R1
R
G
R3
R2 = 100 FOR VALUES SHOWN
LT2078/79 • TA05
INPUT BIAS CURRENT TYPICALLY < 150pA
INPUT RESISTANCE = 3R = 30M FOR VALUES SHOWN
NEGATIVE COMMON MODE LIMIT = (I
B
)(2R) + 20mV 140mV
GAIN BANDWIDTH PRODUCT = 1.8MHz
Picoampere Input Current, Triple Op Amp
Instrumentation Amplifier with Bias Current Cancellation 85V, –100V Common Mode Range
Instrumentation Amplifier (AV = 10)
+
+
6
5
7
1/2 LT2078
100k
100k
1/2 LT2078
2
3
1
OUTPUT
8V TO –9V
LT2078/79 • TA06
BANDWIDTH= 2kHz
OUTPUT OFFSET= 8mV
OUTPUT NOISE= 0.8mV
P-P
(0.1Hz TO 10Hz)
= 1.4mV
RMS
OVER FULL BANDWIDTH
(DOMINATED BY RESISTOR NOISE)
9V
–9V
8
4
1M
10M
1M
10M
10M
+IN
–IN
INPUT RESISTANCE = 10M
Absolute Value Circuit (Full-Wave Rectifier)
+
+
5
6
7
1/2 LT2078
1/2 LT2078
2
3
1
OUTPUT
LT2078/79 • TA08
VOMIN = 4mV
NO DISTORTION TO 100Hz
5V
8
4
200k
200k
INPUT
1N4148
3.5V
3.5V
0V
3.5V
Half-Wave Rectifier
+
1/2 LT2078 OUTPUT
LT2078/79 • TA07
V
OMIN
= 6mV
NO DISTORTION TO 100Hz
3V
2M
2M
1M
INPUT
1.8V
–1.8V
1.8V
0V
Programmable Gain Amplifier (Single Supply)
13
12
14 OUT
+
1/4 LT2079
9
10
+
1/4 LT2079
6
5
+
1/4 LT2079
2
3
88
3
1
2
7
4
9
A
C
B
+
1/4 LT2079
7
CD4016B
13 5 6
11
4
11
1
3V TO 18V 3V TO 18V
1M100k10k1.11k
IN
LT2078/79 • TA09
ERROR DUE TO SWITCH ON RESISTANCE,
LEAKAGE CURRENT, NOISE AND TRANSIENTS
ARE ELIMINATED
CD4016B
GAIN PIN 13 PIN 5 PIN 6
1000 HIGH LOW LOW
100 LOW HIGH LOW
10 LOW LOW HIGH
14
LT2078/LT2079
20789fa
TYPICAL APPLICATIONS
U
Single Supply, Micropower, Second Order Lowpass Filter with 60Hz Notch
+
+
6
5
7
1/2 LT2078
2.64M
0.1%
2.64M
0.1%
1/2 LT2078
3
2
1
OUTPUT
TYPICAL OFFSET
600µV
LT2078/79 • TA10
5V
8
4
1.35M
0.1%
IN
2000pF
0.5%
1000pF
0.5%
1000pF
0.5%
0.02µF
5.1M
1% 120k
5%
100pF
0.01µF
27.6k
0.1%
27.6k
0.1%
f
C
= 40Hz
Q = 30
Micropower Multiplier/Divider
+
6
5
13
12
1/4 LT2079
4
11
714
+
2
3
1/4 LT2079 1
+
9
10 1/4 LT2079 8
1.5V TO –9V
9V
505k
0.1% 505k
0.1%
505k
0.1%
220pF 220pF
30k
5%
30k
5%
Q1
+
220pF
30k
5%
Y INPUT
(5mV TO 50V)
X INPUT
(5mV TO 50V)
Q2 Q4
499k
0.5%
10k
GAIN
Z INPUT
(5mV TO 50V)
OUTPUT
(5mV TO 8V)
1/4 LT2079
Q1,Q2, Q3, Q4 = MAT-04
TYPICAL LINEARITY = 0.01% OF FULL-SCALE OUTPUT
Q3
OUTPUT = , POSITIVE INPUTS ONLY
(X)(Y)
(Z)
NEGATIVE SUPPLY CURRENT = 165µA + X + Y+ Z + OUT
500k
POSITIVE SUPPLY CURRENT = 165µA +
BANDWIDTH (< 3V
P-P
SIGNAL): X AND Y INPUTS = 10kHz
Z INPUT = 4kHz
OUT
500k
lt2078/79 • TA11
Micropower Dead Zone Generator
+
2
3
1
1/4 LT2079
510k
1M**
1M** 1M*
Q1
2N4393
+
6
5
7
1/4 LT2079
+
9
10
8
1/4 LT2079
+
13
12
14
1/4 LT2079
1M**
Q4
Q2 Q3
470k
1M*
GAIN
200k
510k
1M**
510k
4
11
9V
1M
1M 680k
1M
1N914
1N914
Q5
–9V
Q6
2N4393
1000pF
VSET
DEAD ZONE
CONTROL INPUT
0.4V TO 5V
VOUT
LT2078/79 • TA12
BIPOLAR SYMMETRY IS EXCELLENT
BECAUSE ONE DEVICE, Q2,
SETS BOTH LIMITS
SUPPLY CURRENT 240µA
BANDWIDTH = 150kHz
INPUT
*
**1% FILM
RATIO MATCH 0.05%
Q2, Q3, Q4, Q5 CA3096 TRANSISTOR ARRAY
VSET
VSET
VOUT
VIN
15
LT2078/LT2079
20789fa
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
TYPICAL APPLICATIONS
U
Lead-Acid Low-Battery Detector with System Shutdown
+
+
2
3
1
6
5
7
8
4
1/2 LT2078
1/2 LT2078
2M
1% 2M
1%
255k
1% 280k
1%
910k
5%
LT1004-1.2
LO = BATTERY LOW
(IF V
S
< 10.90V)
LO = SYSTEM SHUTDOWN
(IF V
S
< 10.05V)
BATTERY
OUTPUT
LT2078/79 • TA13
TOTAL SUPPLY CURRENT = 105µA
12V
PACKAGE DESCRIPTION
U
.016 – .050
(0.406 – 1.270)
.010 – .020
(0.254 – 0.508)× 45°
0°– 8° TYP
.008 – .010
(0.203 – 0.254)
SO8 0303
.053 – .069
(1.346 – 1.752)
.014 – .019
(0.355 – 0.483)
TYP
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
1234
.150 – .157
(3.810 – 3.988)
NOTE 3
8765
.189 – .197
(4.801 – 5.004)
NOTE 3
.228 – .244
(5.791 – 6.197)
.245
MIN .160 ±.005
RECOMMENDED SOLDER PAD LAYOUT
.045 ±.005
.050 BSC
.030 ±.005
TYP
INCHES
(MILLIMETERS)
NOTE:
1. DIMENSIONS IN
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)