LINER LT2078AIS8 Micropower, dual and quad, single supply, precision op amp Datasheet

LT 2078/LT 2079
Micropower, Dual and
Quad, Single Supply,
Precision Op Amps
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FEATURES
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DESCRIPTION
SO Package with Standard Pinout
Supply Current per Amplifier: 50µA Max
Offset Voltage: 70µV Max
Offset Current: 250pA Max
Voltage Noise: 0.6µVP-P, 0.1Hz to 10Hz
Current Noise: 3pAP-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
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APPLICATIONS
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Battery or Solar-Powered Systems
Portable Instrumentation
Remote Sensor Amplifier
Satellite Circuitry
Micropower Sample-and-Hold
Thermocouple Amplifier
Micropower Filters
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 supply current without sacrificing other parameters. The
offset voltage achieved is the lowest on any dual or quad
nonchopper stabilized op amp––micropower or otherwise. 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 resistors are needed. For applications requiring DIP packages
refer to the LT1078/LT1079.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATION
Single Battery, Micropower, Gain = 100, Instrumentation Amplifier
1M
2
INVERTING 3
–INPUT
–
A
1/2 LT2078
1
10.1k
6
+
NONINVERTING 5
+INPUT
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
–
1M
3V
(Li-Ion)
8
700
B
1/2 LT2078
+
4
7
OUT
LT2078/79 • TA01
OUTPUT NOISE = 85 µVP-P 0.1Hz TO 10Hz
= 300 µVRMS OVER FULL BANDWIDTH
INPUT RANGE = 0.03V TO 1.8V
OUTPUT RANGE= 0.03V TO 2.3V
(0.3mV ≤ VIN+ – VIN– ≤ 23mV)
OUTPUTS SINK CURRENT—NO PULL-DOWN RESISTORS
NUMBER OF OP AMPS
10.1k
Distribution of Input Offset Voltage
800
VS = 5V, 0V
5000 OP AMPS
600
500
400
300
200
100
0
–120
–80
–40
40
80
0
INPUT OFFSET VOLTAGE (µV)
120
2078/79 • TA02
1
LT2078/LT 2079
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ABSOLUTE MAXIMUM RATINGS
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
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PACKAGE/ORDER INFORMATION
ORDER PART
NUMBER
TOP VIEW
OUT A 1
–IN A 2
A
+IN A 3
V– 4
B
8
V+
7
OUT B
6
–IN B
5
+IN B
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 150°C, θJA = 190°C/ W
LT2078ACS8
LT2078AIS8
LT2078CS8
LT2078IS8
PART MARKING
2078A 2078
2078AI 2078I
ORDER PART
NUMBER
TOP VIEW
14 OUT D
OUT A 1
–IN A 2
A
D
V+ 4
LT2079AC
LT2079AI
LT2079C
LT2079I
11 V –
10 +IN C
+IN B 5
–IN B 6
13 –IN D
12 +IN D
+IN A 3
B
C
OUT B 7
9
–IN C
8
OUT C
S PACKAGE
14-LEAD PLASTIC SO
TJMAX = 150°C, θJA = 150°C/ W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, TA = 25°C, unless otherwise noted.
CONDITIONS (NOTE 1)
LT2078AC/LT2078AI
LT2079AC/LT2079AI
MIN
TYP
MAX
LT2078C/LT2078I
LT2079C/LT2079I
MIN
TYP
MAX
30
35
40
40
70
110
120
150
µV
µV
VOS
Input Offset Voltage
∆VOS
∆Time
Long Term Input Offset
Voltage Stability
0.4
IOS
Input Offset Current
0.05
0.25
0.05
0.35
nA
IB
Input Bias Current
6
8
6
10
nA
en
Input Noise Voltage
0.1Hz to 10Hz (Note 2)
0.6
1.2
0.6
µVP-P
Input Noise Voltage Density
fO = 10Hz (Note 2)
fO = 1000Hz (Note 2)
29
28
45
37
29
28
nV√Hz
nV√Hz
Input Noise Current
0.1Hz to 10Hz (Note 2)
2.3
4.0
2.3
pAP-P
Input Noise Current Density
fO = 10Hz (Note 2)
fO = 1000Hz
0.06
0.02
0.10
0.06
0.02
pA√Hz
pA√Hz
Input Resistance
Differential Mode
Common Mode
(Note 3)
in
LT2078
LT2079
UNITS
µV/Mo
0.5
400
800
6
300
800
6
MΩ
GΩ
Input Voltage Range
3.5
0
3.8
– 0.3
3.5
0
3.8
– 0.3
V
V
CMRR
Common Mode Rejection Ratio VCM = 0V to 3.5V
95
110
92
108
dB
PSRR
Power Supply Rejection Ratio
100
114
98
114
dB
2
VS = 2.3V to 12V
LT 2078/LT 2079
ELECTRICAL CHARACTERISTICS
CONDITIONS (NOTE 1)
LT2078AC/LT2078AI
LT2079AC/LT2079AI
MIN
TYP
MAX
LT2078C/LT2078I
LT2079C/LT2079I
MIN
TYP
MAX
Large-Signal Voltage Gain
VO = 0.03V to 4V, No Load
VO = 0.03V to 3.5V, RL = 50k
200
150
150
120
Maximum Output Voltage
Swing
Output Low, No Load
Output Low, 2k to GND
Output Low, ISINK = 100µA
SYMBOL PARAMETER
AVOL
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, TA = 25°C, unless otherwise noted.
1000
600
3.5
0.55
95
6
1.0
130
1000
600
3.5
0.55
95
UNITS
V/mV
V/mV
6
1.0
130
mV
mV
mV
Output High, No Load
Output High, 2k to GND
4.2
3.5
4.4
3.9
4.2
3.5
4.4
3.9
V
V
0.04
0.07
0.04
0.07
V/µs
200
kHz
SR
Slew Rate
AV = 1, VS = ±2.5V
GBW
Gain Bandwidth Product
fO ≤ 20kHz
IS
Supply Current per Amplifier
200
38
Channel Separation
∆VIN = 3V, RL = 10k, f ≤ 10Hz
110
Minimum Supply Voltage
(Note 4)
2.2
50
39
55
110
2.3
2.2
µA
dB
2.3
V
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, – 40°C ≤ TA ≤ 85°C for I grades, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
LT2078AI/LT2079AI
MIN
TYP
MAX
LT2078I/LT2079I
MIN
TYP
MAX
UNITS
VOS
Input Offset Voltage
LT2078
LT2079
●
●
70
80
250
280
95
100
370
400
µV
µV
∆VOS
∆T
Input Offset Voltage Drift
(Note 5)
LT2078
LT2079
●
●
0.4
0.6
1.8
3.0
0.5
0.6
2.5
3.5
µV/°C
µV/°C
IOS
Input Offset Current
●
0.07
0.70
0.1
1.0
nA
IB
Input Bias Current
●
7
10
7
12
nA
CMRR
Common Mode Rejection Ratio VCM = 0.05V to 3.2V
●
90
106
86
104
dB
PSRR
Power Supply Rejection Ratio
VS = 3.1V to 12V
●
96
110
92
110
dB
AVOL
Large-Signal Voltage Gain
VO = 0.05V to 4V, No Load
VO = 0.05V to 3.5V, RL = 50k
●
●
110
80
600
400
80
60
600
400
V/mV
V/mV
Maximum Output Voltage
Swing
Output Low, No Load
Output Low, ISINK = 100µA
●
●
Output High, No Load
Output High, 2k to GND
●
●
IS
Supply Current per Amplifier
4.5
125
3.9
3.0
4.2
3.7
43
●
8
170
4.5
125
3.9
3.0
60
8
170
4.2
3.7
45
mV
mV
V
V
70
µA
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, 0°C ≤ TA ≤ 70°C, unless otherwise noted (Note 6).
LT2078AC/LT2079AC
MIN
TYP
MAX
LT2078C/LT2079C
MIN
TYP
MAX
●
●
50
60
150
180
60
70
240
270
µV
µV
●
●
0.4
0.5
1.8
3.0
0.5
0.6
2.5
3.5
µV/°C
µV/°C
Input Offset Current
●
0.06
0.35
0.06
0.50
nA
IB
Input Bias Current
●
6
9
6
11
nA
CMRR
Common Mode Rejection Ratio VCM = 0V to 3.4V
●
92
108
88
106
dB
PSRR
Power Supply Rejection Ratio
●
98
112
95
112
dB
SYMBOL PARAMETER
CONDITIONS
VOS
Input Offset Voltage
LT2078
LT2079
∆VOS
∆T
Input Offset Voltage Drift
(Note 5)
LT2078
LT2079
IOS
VS = 2.6V to 12V
UNITS
3
LT2078/LT 2079
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
AVOL
IS
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, 0°C ≤ TA ≤ 70°C, unless otherwise noted.
CONDITIONS
Large-Signal Voltage Gain
VO = 0.05V to 4V, No Load
VO = 0.05V to 3.5V, RL = 50k
●
●
Maximum Output Voltage
Swing
Output Low, No Load
Output Low, ISINK = 100µA
●
●
Output High, No Load
Output High, 2k to GND
●
●
Supply Current per Amplifier
LT2078AC/LT2079AC
MIN
TYP
MAX
LT2078C/LT2079C
MIN
TYP
MAX
150
110
110
80
750
500
4.0
105
4.1
3.3
4.3
3.8
40
●
7
150
750
500
4.0
105
4.1
3.3
55
V/mV
V/mV
7
150
4.3
3.8
42
UNITS
mV
mV
V
V
63
µA
VS = ±15V, TA = 25°C, unless otherwise noted.
SYMBOL PARAMETER
VOS
Input Offset Voltage
IOS
Input Offset Current
IB
Input Bias Current
CONDITIONS
LT2078AC/LT2078AI
LT2079AC/LT2079AI
MIN
TYP
MAX
LT2078C/LT2078I
LT2079C/LT2079I
MIN
TYP
MAX
50
60
250
350
70
80
350
450
µV
µV
0.05
0.25
0.05
0.35
nA
6
8
6
10
nA
LT2078
LT2079
Input Voltage Range
UNITS
13.5
–15.0
13.8
–15.3
13.5
–15.0
13.8
–15.3
V
V
98
114
95
114
dB
CMRR
Common Mode Rejection Ratio VCM = 13.5V, –15V
PSRR
Power Supply Rejection Ratio
VS = 5V, 0V to ±18V
100
114
98
114
dB
AVOL
Large-Signal Voltage Gain
VO = ±10V, RL = 50k
VO = ±10V, RL = 2k
1000
400
5000
1100
1000
300
5000
1100
V/mV
V/mV
VOUT
Maximum Output Voltage
Swing
RL = 50k
RL = 2k
±13.0
±11.0
±14.0
±13.2
±13.0
±11.0
±14.0
±13.2
V
V
SR
Slew Rate
0.06
0.10
0.06
0.10
V/µs
IS
Supply Current per Amplifier
46
65
47
75
µA
VS = ±15V, – 40°C ≤ TA ≤ 85°C for I grades, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
LT2078AI/LT2079AI
MIN
TYP
MAX
LT2078I/LT2079I
MIN
TYP
MAX
UNITS
VOS
Input Offset Voltage
LT2078
LT2079
●
●
90
100
430
500
120
130
600
700
µV
µV
∆VOS
∆T
Input Offset Voltage Drift
(Note 5)
LT2078
LT2079
●
●
0.5
0.6
1.8
3.0
0.6
0.7
2.5
3.8
µV/°C
µV/°C
IOS
Input Offset Current
●
0.07
0.70
0.1
1.0
nA
IB
Input Bias Current
●
7
10
7
12
nA
AVOL
Large-Signal Voltage Gain
VO = ±10V, RL = 5k
●
200
700
150
700
V/mV
CMRR
Common Mode Rejection Ratio VCM = 13V, –14.9V
●
92
110
88
110
dB
PSRR
Power Supply Rejection Ratio
●
96
110
92
110
dB
Maximum Output Voltage Swing RL = 5k
●
±11.0
±13.5
±11.0
±13.5
V
Supply Current per Amplifier
●
IS
4
VS = 5V, 0V to ±18V
52
80
54
95
µA
LT 2078/LT 2079
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
VS = ±15V, 0°C ≤ TA ≤ 70°C, unless otherwise noted (Note 6).
CONDITIONS
LT2078AC/LT2079AC
MIN
TYP
MAX
LT2078C/LT2079C
MIN
TYP
MAX
UNITS
VOS
Input Offset Voltage
LT2078
LT2079
●
●
70
80
330
410
90
100
460
540
µV
µV
∆VOS
∆T
Input Offset Voltage Drift
(Note 5)
LT2078
LT2079
●
●
0.5
0.6
1.8
3.0
0.6
0.7
2.5
3.8
µV/°C
µV/°C
IOS
Input Offset Current
●
0.06
0.35
0.06
0.50
nA
IB
Input Bias Current
●
6
9
6
11
nA
AVOL
Large-Signal Voltage Gain
VO = ±10V, RL = 5k
●
300
1200
250
1200
V/mV
CMRR
Common Mode Rejection Ratio
VCM = 13V, –15V
●
95
112
92
112
dB
PSRR
Power Supply Rejection Ratio
VS = 5V, 0V to ±18V
●
98
112
95
112
dB
Maximum Output Voltage Swing
RL = 5k
●
±11.0
±13.6
±11.0
±13.6
V
IS
Supply Current per Amplifier
49
●
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: 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 2: This parameter is tested on a sample basis only. All noise
parameters are tested with VS = ±2.5V, VO = 0V.
73
50
µA
85
Note 3: This parameter is guaranteed by design and is not tested.
Note 4: 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 5: This parameter is not 100% tested.
Note 6: 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.
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TYPICAL PERFORMANCE CHARACTERISTICS
15
10
5
0
–2
0
1
–1
2
OFFSET VOLTAGE DRIFT WITH TEMPERATURE (µV/°C)
LT2078/79 • TPC01
100
–5
Input Bias Current vs
Common Mode Voltage
0
VS = 5V, 0V TO ±15V
50
VS = 5V, 0V
–2
IOS
INPUT BIAS CURRENT (nA)
PERCENT OF UNITS (%)
20
VS = 5V, 0V
VCM = 0.1V
80 LT2078'S
25 LT2079'S
= 260 OP AMPS
OFFSET CURRENT (pA)
25
Input Bias and Offset Currents vs
Temperature
BIAS CURRENT (nA)
Distribution of Offset Voltage
Drift with Temperature
0
IB
–6
–7
–50 –25
TA = 125°C
TA = –55°C
–4
TA = 25°C
–6
–8
–10
50
25
0
75
TEMPERATURE (°C)
100
125
LT2078/79 • TPC02
–12
–1
0
1
2
3
COMMON MODE VOLTAGE (V)
4
LT2078/79 • TPC03
5
LT2078/LT 2079
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TYPICAL PERFORMANCE CHARACTERISTICS
0.01Hz to 10Hz Noise
0.1Hz to 10Hz Noise
Noise Spectrum
1000
CHANNEL B
VOLTAGE NOISE DENSITY (nV/√Hz)
CURRENT NOISE DENSITY (fA/√Hz)
TA = 25°C
VS = ±2.5V
CHANNEL A
NOISE VOLTAGE (0.4µV/DIV)
NOISE VOLTAGE (0.4µV/DIV)
TA = 25°C
VS = ±2.5V
CHANNEL A
0.4µV
300
CURRENT
NOISE
100
VOLTAGE
NOISE
30
1/f CORNER
0.7Hz
CHANNEL B
0
2
6
4
TIME (SEC)
8
0
10
20
60
40
TIME (SEC)
80
20
15
10
5
0
0.8
TA = 25°C, VS = 5V, 0V
VCM = 0.1V
10
CHANGE IN OFFSET VOLTAGE (µV)
OFFSET VOLTAGE CHANGE (µV)
1A
5
0
2B
–5
1B
–10
2A
–15
25
35
30
VOLTAGE NOISE DENSITY (nV/√Hz)
40
1
2
3
TIME (MONTHS)
4
0°C
25°C
–55°C
NONFUNCTIONAL
SATURATION VOLTAGE (mV)
INPUT OFFSET VOLTAGE (µV)
70°C
6
1
0
2
ISINK = 1mA
100
ISINK = 100µA
ISINK = 10µA
VS = 5V, 0V
10
ISINK = 1µA
NO LOAD
1
–50 –25
3
LT2078/79 • TPC09
Output Voltage Swing vs
Load Current
125°C
RL = 5k TO GND
LT2078/79 • TPC10
LT2078
0.1
V+
–400
2
3
1
POSITIVE SUPPLY VOLTAGE (V)
LT2079
0.2
ISINK = 2mA
–100
0
0.3
5
1000
125°C
–300
0.4
Output Saturation vs Temperature
vs Sink Current
V – = 0V
–0.1V ≤ VCM ≤ 0.4V
–200
0.5
LT2078/79 • TPC08
Minimum Supply Voltage
0
0.6
TIME AFTER POWER-ON (MINUTES)
LT2078/79 • TPC07
100
TA = 25°C
VS = ±15V
WARM UP DRIFT
AT VS = 5V, 0V IS
IMMEASURABLY LOW
0.7
0
0
0
25
50
75
TEMPERATURE (°C)
100
125
LT2078/79 • TPC11
OUTPUT VOLTAGE SWING (V)
PERCENT OF UNITS
25
1000
Warm-Up Drift
15
35
TA = 25°C
VS = ±2.5V
100
10
FREQUENCY (Hz)
LT2078/79 • TPC06
Long Term Stability of Two
Representative Units (LT2078)
10Hz Voltage Noise Distribution
30
1
LT2078/79 • TPC05
LT2078/79 • TPC04
–500
10
0.1
100
TA = 25°C
VS = ±2.5V
(AT VS = ±15V
VOLTAGE NOISE
IS 4% LESS
CURRENT NOISE
IS UNCHANGED)
V+ – 1
25°C
–55°C
V+ – 2
V– + 2
125°C
V– + 1
25°C
–55°C
V–
0.1
1
10
0.01
SOURCING OR SINKING LOAD CURRENT (mA)
LT2078/79 • TPC11.5
LT 2078/LT 2079
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TYPICAL PERFORMANCE CHARACTERISTICS
Gain, Phase vs Frequency
10M
5V, 0V
120
100
140
PHASE
MARGIN
46°
10
160
5V, 0V
180
±15V
200
0
PHASE SHIFT (DEG)
±15V
120
VS = ±15V
VS = 5V, 0V
TA = 25°C
VS = ±15V
80
VS = 5V, 0V
60
25°C
125°C
VOLTAGE GAIN (V/V)
20
100
VOLTAGE GAIN (dB)
PHASE
MARGIN
58°
VOLTAGE GAIN (dB)
Voltage Gain vs Load Resistance
Voltage Gain vs Frequency
140
30
40
–55°C
–55°C
1M
25°C
125°C
20
0
–20
0.01 0.1
–10
10
30
1000
100
300
FREQUENCY (kHz)
65
φM = ±15V
0.04
55
45
φM = 5V, 0V
GBW = ±15V
220
200
GBW = 5V, 0V
100
100
80
80
60
40
TA = 25°C
VS = ±2.5V
VIN = 3VP-P
RL = 10k
20
fO = 20kHz
160
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
1
10
100
1k
10k
FREQUENCY (Hz)
VS = ±15V
RL = 30k
3
10
2
TA = 25°C
LOAD RL,
TO GND
0
0.01
1
1
10
FREQUENCY (kHz)
100k
0
100
LT2078/79 • TPC18
AV = 10
100
1000
CAPACITIVE LOAD (pF)
10
1M
10000
LT2078/79 • TPC17
Power Supply Rejection Ratio
vs Frequency
120
120
COMMON MODE REJECTION RATIO (dB)
4
PEAK-TO-PEAK OUTPUT SWING, VS = 5V, 0V (V)
5
VS = 5V, 0V
RL ≥ 100k
VS = 5V, 0V
RL ≥ 1k
AV = 5
40
Common Mode Rejection Ratio
vs Frequency
VS = ±15V
RL ≥ 100k
20
60
LT2078/79 • TPC16
Undistorted Output Swing
vs Frequency
30
AV = 1
0
0
125
LT2078/79 • TPC15
PEAK-TO-PEAK OUTPUT SWING, VS = ±15V (V)
TA = 25°C
VS = 5V, 0V
20
TA = 25°C
POWER SUPPLY REJECTION RATIO (dB)
0.06
180
Capacitive Load Handling
120
OVERSHOOT (%)
75
SLEW = 5V, 0V
CHANNEL SEPARATION (dB)
SLEW RATE (V/ µs)
240
Channel Separation vs Frequency
SLEW = ±15V
0.08
1M
LT2078/79 • TPC14
120
PHASE MARGIN (DEG)
GAIN BANDWIDTH
PRODUCT (kHz)
Slew Rate, Gain Bandwidth Product
and Phase Margin vs Temperature
0.10
1k
10k
100k
LOAD RESISTANCE TO GROUND (Ω)
LT2078/79 • TPC13
LTC2078/79 TPC12
0.12
100k
100
10 100 1k 10k 100k 1M
FREQUENCY (Hz)
1
100
VS = ±15V
80
VS = 5V, 0V
60
40
20
0
10
100
1k
10k
FREQUENCY (Hz)
100k
1M
LT2078/79 • TPC19
100
80
NEGATIVE
SUPPLY
60
POSITIVE
SUPPLY
40
20
0
0.1
TA = 25°C
VS = ±2.5V + 1VP-P SINE WAVE
1
10
100 1k
10k
FREQUENCY (Hz)
100k
1M
LT2078/79 • TPC20
7
LT2078/LT 2079
U W
TYPICAL PERFORMANCE CHARACTERISTICS
Common Mode Range vs
Temperature
V+
50
V+ – 1
VS = ±15V
45
40
VS = 5V, 0V
35
30
Closed-Loop Output Impedance
V + = 2.5V TO 18V
V – = 0V TO –18V
1k
OUTPUT IMPEDANCE (Ω)
55
COMMON MODE RANGE (V)
V+ – 2
V– + 1
V–
AV = 100
100
AV = 10
10
AV = 1
1
0.1
25
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
V– – 1
–50 –25
0
25
50
75
TEMPERATURE (°C)
LT2078/79 • TPC21
100
1k
10k
FREQUENCY (Hz)
0V
Small-Signal Transient Response
VS = ± 15V
0V
AV = 1
CL = 15pF
LT2078/79 • TPC24
10µs/DIV
0V
AV = 1
CL = 15pF
10µs/DIV
LT2078/79 • TPC25
LT2078/79 • TPC26
Large-Signal Transient Response
VS = ± 15V
5V/DIV
1V/DIV
Large-Signal Transient Response
VS = 5V, 0V
0V
0V
AV = 1
NO LOAD
AV = 1, NO LOAD
50µs/DIV
INPUT PULSE 0V TO 3.8V
LT2078/79 • TPC27
8
100k
LT2078/79 • TPC23
Small-Signal Transient Response
VS = ± 2.5V
20mV/DIV
20mV/DIV
10
125
LT2078/79 • TPC22
Small-Signal Transient Response
VS = 5V, 0V
AV = 1
10µs/DIV
CL = 15pF
INPUT 50mV TO 150mV
100
20mV/DIV
SUPPLY CURRENT PER AMPLIFIER (µA)
Supply Current vs Temperature
100µs/DIV
LT2078/79 • TPC28
LT 2078/LT 2079
W
W
SI PLIFIED SCHEMATIC
1/2 LT2078, 1/4 LT2079
V+
10k
10k
2.2k
5.6k
11.5k
5k
3.6k
1.3k
Q54
1
Q16
Q6
Q5
Q14
Q15
Q53
2
1
Q32
Q52
Q47
Q4
Q46
Q37
Q29
Q3
Q30
Q24
1
V–
3
Q12
8.6k
4
Q11
C1
50pF
Q40
3k
Q25
Q35
V
1
2.9k
30Ω
Q44
C5
2.5pF
Q27
IN +
600Ω
600Ω
Q41
+
Q26
C4
4pF
OUT
IN –
12.5k
Q1
Q21
150k
Q18
Q28
Q2
Q22
V+
Q31
C3
40pF
J1
Q36
Q33
Q48
Q19
Q50
Q42
Q49
Q39
Q9
Q23
Q10 Q17
C2
175pF
Q7
Q8
V+
Q34
6.2k
6.2k
9.1k
Q45
Q20
1.35k
Q51
Q55
10k
Q38
30Ω
700k
Q43
4A
5.35k
700k
V–
LT2078/79 • SIMPLIFIED SCHEM
9
LT2078/LT 2079
U
W
U
U
APPLICATIONS INFORMATION
The LT2078/LT2079 devices are fully specified with
V + = 5V, V – = 0V, VCM = 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, VS = ±2.5V, VCM = 0V is equivalent
to a common mode voltage change of 2.4V or a VOS
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 completeness.
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, OP420) 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 applications 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 competing 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):
5V
5V
R
–
99R
–
100mV
1mV
+
LT2078/79 • F02a
Figure 1a. Gain 100 Amplifier
10
1mV
+
OUTPUT
SATURATION
≈ 3.5mV
LT2078/79 • F02b
Figure 1b. Voltage Follower
LT 2078/LT 2079
U
W
U
U
APPLICATIONS INFORMATION
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 circuitry, 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 operating inverting there is no common mode induced distortion. Crossover distortion will increase as the output load
resistance decreases. For the lowest distortion the LT2078/
LT2079 should be operated with the output always sourcing current, this is usually accomplished by putting a
resistor from the output to V –. In an inverting configuration with no load, the output will source and sink current
through the feedback resistor. High value feedback resistors will reduce crossover distortion and maintain
micropower operation.
Matching Specifications
In many applications the performance of a system depends on the matching between two op amps, rather than
Table 1
PARAMETER
VOS Match, ∆VOS
LT2078
LT2079
Temperature Coefficient ∆VOS
Average Noninverting IB
Match of Noninverting IB
CMRR Match
PSRR Match
LT2078AC/LT2079AC/LT2078AI/LT2079AI
50% YIELD
98% YIELD
30
110
40
150
0.5
1.2
6
8
0.12
0.4
120
100
117
105
LT2078C/LT2079C/LT2078I/LT2079I
50% YIELD
98% YIELD
50
190
50
250
0.6
1.8
6
10
0.15
0.5
117
97
117
102
4V
4V
4V
2V
2V
2V
0V
0V
0V
6VP-P INPUT
–1V TO 5V
1ms/DIV
1ms/DIV
OP-90 EXHIBITS OUTPUT PHASE REVERSAL
LT2078/79 • F01a
UNITS
µV
µV
µV/°C
nA
nA
dB
dB
1ms/DIV
LT2078/LT2079 NO PHASE REVERSAL
LT2078/79 • F01b
LT2078/79 • F01C
Figure 2. Voltage Follower with Input Exceeding the Negative Common Mode Range (VS = 5V, 0V)
11
LT2078/LT 2079
U
U
W
U
APPLICATIONS INFORMATION
the individual characteristics of the two devices, the two
and three op amp instrumentation amplifier configurations 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 mismatch 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 VS = 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.
4
OUTPUT (V)
2
2
0
0
0
100
–100
INPUT (mV)
INPUT (mV)
OUTPUT (V)
4
VS = 5V, 0V
200µs/DIV
0
VS = 5V, 0V
200µs/DIV
LT2078/79 • F03
LT2078/79 • F04
Figure 3. Comparator Rise Response
Time to 10mV, 5mV, 2mV Overdrives
Figure 4. Comparator Fall Response
Time to 10mV, 5mV, 2mV Overdrives
U
TYPICAL APPLICATIONS
Micropower, 10ppm/°C, ±5V Reference
2M
LT1034BC-1.2
10M
9V
220k
3V
5VOUT
120k
3
+
–
1
1M
510k
4
–9V
20k
1M
1M
–IN
8
1/2 LT2078
2
160k
1%
Gain of 10 Difference Amplifier
6
1M
1/2 LT2078
5
+IN
–
+
7
–5.000VOUT
LT2078/79 • TA03
510k
1%
SUPPLY CURRENT = 9V BATTERY = 115µA
–9V BATTERY = 85 µA
OUTPUT NOISE = 36µVP-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
12
–
1/2 LT2078
+
10M
OUTPUT
0.0035V TO 2.4V
LT2078/79 • TA04
BANDWIDTH= 20kHz
OUTPUT OFFSET= 0.7mV
OUTPUT NOISE= 80 µVP-P (0.1Hz TO 10Hz)
260 µVRMS 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
LT 2078/LT 2079
U
TYPICAL APPLICATIONS
Picoampere Input Current, Triple Op Amp
Instrumentation Amplifier with Bias Current Cancellation
3
–IN
+
2
R2
1M
1
1/4 LT2079
1M
9V
R1
1M
–
2R
20M
9
7
1/4 LT2079
5
+IN
R
10M
12
2R
20M
10
+
+
–
2
10M
3
OUTPUT
4mV TO 8.2V
+
+
(
4
1/2 LT2078
7
OUTPUT
8V TO –9V
+
LT2078/79 • TA06
Absolute Value Circuit (Full-Wave Rectifier)
200k
200k
–
INPUT
2
OUTPUT
1/2 LT2078
5V
3.5V
8
0V
–
1/2 LT2078
+
3
3.5V
1
5
1N4148
+
4
VOMIN = 6mV
NO DISTORTION TO 100Hz
+
1/2 LT2078
6
7
OUTPUT
–
–3.5V
1.8V
LT2078/79 • TA08
0V
–1.8V
5
INPUT BIAS CURRENT TYPICALLY < 150pA
INPUT RESISTANCE = 3R = 30M FOR VALUES SHOWN
NEGATIVE COMMON MODE LIMIT = (IB)(2R) + 20mV ≈ 140mV
GAIN BANDWIDTH PRODUCT = 1.8MHz
11
1.8V
100k
–
)
3V
1M
6
GAIN = 1 + 2R1 R3 = 100 FOR VALUES SHOWN
RG R2
14
2M
INPUT
100k
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)
INPUT RESISTANCE =10M
LT2078/79 • TA05
Half-Wave Rectifier
2M
1
–9V
1M
R3
9.1M
9V
4
–
–
8
10M
8
1/2 LT2078
–IN
1/4 LT2079
R2
1M
1/4 LT2079
13
R1
1M
–
10M
+IN
R3
9.1M
RG
200k
6
85V, –100V Common Mode Range
Instrumentation Amplifier (AV = 10)
VOMIN = 4mV
NO DISTORTION TO 100Hz
LT2078/79 • TA07
Programmable Gain Amplifier (Single Supply)
1.11k
10k
100k
1M
3V TO 18V
2
–
1/4 LT2079
3
+
3V TO 18V
11
4
11
1
1
6
2
–
1/4 LT2079
5
13
A
7
+
9
10
ERROR DUE TO SWITCH ON RESISTANCE,
LEAKAGE CURRENT, NOISE AND TRANSIENTS
ARE ELIMINATED
1/4 LT2079
12
+
9
–
1/4 LT2079
IN
4
3 B
–
+
C
8 8
7
CD4016B
13
5
6
GAIN PIN 13
1000 HIGH
100
LOW
10
LOW
14
OUT
LT2078/79 • TA09
CD4016B
PIN 5
LOW
HIGH
LOW
PIN 6
LOW
LOW
HIGH
13
LT2078/LT 2079
U
TYPICAL APPLICATIONS
Single Supply, Micropower, Second Order Lowpass Filter with 60Hz Notch
0.02µF
27.6k
0.1%
27.6k
0.1%
3
IN
+
0.01µF
6
5V
8
1
1/2 LT2078
2
–
2.64M
0.1%
2.64M
0.1%
–
5
OUTPUT
TYPICAL OFFSET
≈ 600µV
7
1/2 LT2078
+
2000pF
0.5%
4
5.1M
1%
120k
5%
1.35M
0.1%
100pF
1000pF
0.5%
1000pF
0.5%
fC = 40Hz
Q = 30
LT2078/79 • TA10
Micropower Multiplier/Divider
505k
0.1%
–
220pF
4
30k
5%
+
30k
5%
11
14
Q1,Q2, Q3, Q4 = MAT-04
TYPICAL LINEARITY = 0.01% OF FULL-SCALE OUTPUT
(X)(Y)
OUTPUT =
, POSITIVE INPUTS ONLY
(Z)
1/4 LT2079
10k
GAIN
499k
0.5%
13
12
X + Y+ Z + OUT
500k
OUT
POSITIVE SUPPLY CURRENT = 165µA +
500k
NEGATIVE SUPPLY CURRENT = 165µA +
–1.5V TO –9V
X INPUT
(5mV TO 50V)
505k
0.1%
2
–
3
+
9
–
10
+
220pF
Q2
Z INPUT
(5mV TO 50V)
220pF
Q3
7
1/4 LT2079
5
Q1
+
9V
6
–
Y INPUT
(5mV TO 50V)
505k
0.1%
1/4 LT2079
Q4
8
BANDWIDTH (< 3VP-P SIGNAL): X AND Y INPUTS = 10kHz
Z INPUT = 4kHz
OUTPUT
(5mV TO 8V)
1
1/4 LT2079
30k
5%
lt2078/79 • TA11
Micropower Dead Zone Generator
Q4
1M**
2
INPUT
VSET
DEAD ZONE
CONTROL INPUT
0.4V TO 5V
1M*
1M**
–
Q2
Q3
1
470k
1/4 LT2079
510k
3
+
1M*
Q1
2N4393
9
–
10
+
1M**
GAIN
200k
8
1M
1M**
13
–
510k
12
+
1/4 LT2079
1N914
1/4 LT2079
14
VOUT
LT2078/79 • TA12
9V
6
–
1M
+
1M
Q5
11
–9V
14
510k
Q6
2N4393
VSET
VOUT
1000pF
7
1/4 LT2079
5
680k
4
1N914
VIN
BIPOLAR SYMMETRY IS EXCELLENT
VSET
BECAUSE ONE DEVICE, Q2,
* 1% FILM
SETS BOTH LIMITS
** RATIO MATCH 0.05%
SUPPLY CURRENT ≈ 240µA
Q2, Q3, Q4, Q5 CA3096 TRANSISTOR ARRAY
BANDWIDTH = 150kHz
LT 2078/LT 2079
U
TYPICAL APPLICATIONS
Lead-Acid Low-Battery Detector with System Shutdown
BATTERY
OUTPUT
2M
1%
2M
1%
910k
5%
3
12V
+
1
1/2 LT2078
2
LO = BATTERY LOW
(IF VS < 10.90V)
–
5
8
+
7
1/2 LT2078
255k
1%
6
280k
1%
–
LO = SYSTEM SHUTDOWN
(IF VS < 10.05V)
4
LT1004-1.2
LT2078/79 • TA13
TOTAL SUPPLY CURRENT = 105µA
U
PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
0.189 – 0.197*
(4.801 – 5.004)
(LTC DWG # 05-08-1610)
7
8
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
0.053 – 0.069
(1.346 – 1.752)
0°– 8° TYP
0.016 – 0.050
0.406 – 1.270
0.014 – 0.019
(0.355 – 0.483)
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
5
6
0.228 – 0.244
(5.791 – 6.197)
0.150 – 0.157**
(3.810 – 3.988)
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
BSC
1
3
2
4
SO8 0695
S Package
14-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.337 – 0.344*
(8.560 – 8.738)
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
14
0.053 – 0.069
(1.346 – 1.752)
13
12
11
10
9
8
0.004 – 0.010
(0.101 – 0.254)
0° – 8° TYP
0.150 – 0.157**
(3.810 – 3.988)
0.016 – 0.050
0.406 – 1.270
0.014 – 0.019
(0.355 – 0.483)
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.050
(1.270)
TYP
0.228 – 0.244
(5.791 – 6.197)
S14 0695
1
2
3
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
4
5
6
7
15
LT2078/LT 2079
U
TYPICAL APPLICATION
Platinum RTD Signal Conditioner with Curvature Correction
3V (LITHIUM)
13k*
8
LT1004-1.2
1
+
–
12.3k*
3
10k*
1/2 LT2078
4
1µF
2
50k
5°C
TRIM
43.2k**
1k**
5k
220°C
TRIM
1k**
6
–
5
+
1/2 LT2078
RP = ROSEMOUNT 118MF
** = TRW MAR-6 0.1%
* = 1% METAL FILM
1k**
RP
1k AT
0°C
1µF
7
0.02V TO 2.2VOUT =
2°C TO 220°C ±0.1°C
1.21M*
(SELECT AT 110°C)
LT2078/79 • TA14
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16
Linear Technology Corporation
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LT/GP 1096 7K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977
 LINEAR TECHNOLOGY CORPORATION 1996