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LT 2078/LT 2079 Micropower, Dual and Quad, Single Supply, Precision Op Amps
FEATURES
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DESCRIPTION
The LT (R) 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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SO Package with Standard Pinout Supply Current per Amplifier: 50A Max Offset Voltage: 70V Max Offset Current: 250pA Max Voltage Noise: 0.6VP-P, 0.1Hz to 10Hz Current Noise: 3pAP-P, 0.1Hz to 10Hz Offset Voltage Drift: 0.4V/C Gain Bandwidth Product: 200kHz Slew Rate: 0.07V/s 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
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
TYPICAL APPLICATION
Single Battery, Micropower, Gain = 100, Instrumentation Amplifier
10.1k 1M 1M 3V (Li-Ion) 8 7 OUT
Distribution of Input Offset Voltage
800 700 VS = 5V, 0V 5000 OP AMPS
TYPICAL PERFORMANCE INPUT OFFSET VOLTAGE = 40V INPUT OFFSET CURRENT = 0.2nA TOTAL POWER DISSIPATION = 240W COMMON MODE REJECTION = 110dB (AMPLIFIER LIMITED) GAIN BANDWIDTH PRODUCT = 200kHz
OUTPUT NOISE = 85 VP-P 0.1Hz TO 10Hz = 300 VRMS 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
+
+
INVERTING 3 -INPUT
NONINVERTING 5 +INPUT
-
A 1/2 LT2078
1
10.1k
6
NUMBER OF OP AMPS
-
2
600 500 400 300 200 100 0 -120 -80 -40 40 80 0 INPUT OFFSET VOLTAGE (V) 120
2078/79 * TA02
B 1/2 LT2078 4
LT2078/79 * TA01
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LT2078/LT 2079
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 ............................................. 0C to 70C Industrial ............................................ - 40C to 85C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
PACKAGE/ORDER INFORMATION
TOP VIEW OUT A 1 -IN A 2 +IN A 3 V- 4 A B 8 7 6 5 V+ OUT B -IN B +IN B
ORDER PART NUMBER LT2078ACS8 LT2078AIS8 LT2078CS8 LT2078IS8 PART MARKING 2078A 2078 2078AI 2078I
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 150C, JA = 190C/ W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER VOS VOS Time IOS IB en Input Offset Voltage Long Term Input Offset Voltage Stability Input Offset Current Input Bias Current Input Noise Voltage Input Noise Voltage Density in Input Noise Current Input Noise Current Density Input Resistance Differential Mode Common Mode Input Voltage Range CMRR PSRR Common Mode Rejection Ratio VCM = 0V to 3.5V Power Supply Rejection Ratio VS = 2.3V to 12V LT2078 LT2079
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, TA = 25C, unless otherwise noted.
LT2078AC/LT2078AI LT2079AC/LT2079AI MIN TYP MAX 30 35 0.4 0.05 6 0.25 8 1.2 45 37 4.0 0.10 70 110 LT2078C/LT2078I LT2079C/LT2079I MIN TYP MAX 40 40 0.5 0.05 6 0.6 29 28 2.3 0.06 0.02 300 3.5 0 92 98 800 6 3.8 - 0.3 108 114 0.35 10 120 150
CONDITIONS (NOTE 1)
0.1Hz to 10Hz (Note 2) fO = 10Hz (Note 2) fO = 1000Hz (Note 2) 0.1Hz to 10Hz (Note 2) fO = 10Hz (Note 2) fO = 1000Hz (Note 3) 400 3.5 0 95 100
2
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TOP VIEW OUT A 1 -IN A 2 +IN A 3 V+ 4 +IN B 5 -IN B 6 OUT B 7 B C A D 14 OUT D 13 -IN D 12 +IN D 11 V - 10 +IN C 9 8 -IN C OUT C
ORDER PART NUMBER LT2079AC LT2079AI LT2079C LT2079I
S PACKAGE 14-LEAD PLASTIC SO
TJMAX = 150C, JA = 150C/ W
UNITS V V V/Mo nA nA VP-P nVHz nVHz pAP-P pAHz pAHz M G V V dB dB
0.6 29 28 2.3 0.06 0.02 800 6 3.8 - 0.3 110 114
LT 2078/LT 2079
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER AVOL Large-Signal Voltage Gain Maximum Output Voltage Swing
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, TA = 25C, unless otherwise noted.
LT2078AC/LT2078AI LT2079AC/LT2079AI MIN TYP MAX 200 150 1000 600 3.5 0.55 95 4.2 3.5 0.04 4.4 3.9 0.07 200 38 50 6 1.0 130 4.2 3.5 0.04 LT2078C/LT2078I LT2079C/LT2079I MIN TYP MAX 150 120 1000 600 3.5 0.55 95 4.4 3.9 0.07 200 39 110 2.3 2.2 2.3 55 6 1.0 130
CONDITIONS (NOTE 1) VO = 0.03V to 4V, No Load VO = 0.03V to 3.5V, RL = 50k Output Low, No Load Output Low, 2k to GND Output Low, ISINK = 100A Output High, No Load Output High, 2k to GND
UNITS V/mV V/mV mV mV mV V V V/s kHz A dB V
SR GBW IS
Slew Rate Gain Bandwidth Product Supply Current per Amplifier Channel Separation Minimum Supply Voltage
AV = 1, VS = 2.5V fO 20kHz VIN = 3V, RL = 10k, f 10Hz (Note 4)
110 2.2
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, - 40C TA 85C for I grades, unless otherwise noted.
SYMBOL PARAMETER VOS VOS T IOS IB CMRR PSRR AVOL Input Offset Voltage Input Offset Voltage Drift (Note 5) Input Offset Current Input Bias Current Common Mode Rejection Ratio VCM = 0.05V to 3.2V Power Supply Rejection Ratio Large-Signal Voltage Gain Maximum Output Voltage Swing VS = 3.1V to 12V VO = 0.05V to 4V, No Load VO = 0.05V to 3.5V, RL = 50k Output Low, No Load Output Low, ISINK = 100A Output High, No Load Output High, 2k to GND IS Supply Current per Amplifier CONDITIONS LT2078 LT2079 LT2078 LT2079
q q q q q q q q q q q q q q q
LT2078AI/LT2079AI MIN TYP MAX 70 80 0.4 0.6 0.07 7 90 96 110 80 106 110 600 400 4.5 125 3.9 3.0 4.2 3.7 43 60 8 170 250 280 1.8 3.0 0.70 10
LT2078I/LT2079I MIN TYP MAX 95 100 0.5 0.6 0.1 7 86 92 80 60 104 110 600 400 4.5 125 3.9 3.0 4.2 3.7 45 70 8 170 370 400 2.5 3.5 1.0 12
UNITS V V V/C V/C nA nA dB dB V/mV V/mV mV mV V V A
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, 0C TA 70C, unless otherwise noted (Note 6).
SYMBOL PARAMETER VOS VOS T IOS IB CMRR PSRR Input Offset Voltage Input Offset Voltage Drift (Note 5) Input Offset Current Input Bias Current Common Mode Rejection Ratio VCM = 0V to 3.4V Power Supply Rejection Ratio VS = 2.6V to 12V CONDITIONS LT2078 LT2079 LT2078 LT2079
q q q q q q q q
LT2078AC/LT2079AC MIN TYP MAX 50 60 0.4 0.5 0.06 6 92 98 108 112 150 180 1.8 3.0 0.35 9
LT2078C/LT2079C MIN TYP MAX 60 70 0.5 0.6 0.06 6 88 95 106 112 240 270 2.5 3.5 0.50 11
UNITS V V V/C V/C nA nA dB dB
3
LT2078/LT 2079
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER AVOL Large-Signal Voltage Gain Maximum Output Voltage Swing CONDITIONS
VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, 0C TA 70C, unless otherwise noted.
LT2078AC/LT2079AC MIN TYP MAX
q q q q q q q
LT2078C/LT2079C MIN TYP MAX 110 80 750 500 4.0 105 4.1 3.3 4.3 3.8 42 63 7 150
UNITS V/mV V/mV mV mV V V A
VO = 0.05V to 4V, No Load VO = 0.05V to 3.5V, RL = 50k Output Low, No Load Output Low, ISINK = 100A Output High, No Load Output High, 2k to GND
150 110
750 500 4.0 105 7 150
4.1 3.3
4.3 3.8 40 55
IS
Supply Current per Amplifier
VS = 15V, TA = 25C, unless otherwise noted.
LT2078AC/LT2078AI LT2079AC/LT2079AI MIN TYP MAX 50 60 0.05 6 13.5 -15.0 98 100 1000 400 13.0 11.0 0.06 VS = 5V, 0V to 18V VO = 10V, RL = 50k VO = 10V, RL = 2k RL = 50k RL = 2k 13.8 -15.3 114 114 5000 1100 14.0 13.2 0.10 46 65 250 350 0.25 8 13.5 -15.0 95 98 1000 300 13.0 11.0 0.06 LT2078C/LT2078I LT2079C/LT2079I MIN TYP MAX 70 80 0.05 6 13.8 -15.3 114 114 5000 1100 14.0 13.2 0.10 47 75 350 450 0.35 10
SYMBOL PARAMETER VOS IOS IB Input Offset Voltage Input Offset Current Input Bias Current Input Voltage Range CMRR PSRR AVOL VOUT SR IS
CONDITIONS LT2078 LT2079
UNITS V V nA nA V V dB dB V/mV V/mV V V V/s A
Common Mode Rejection Ratio VCM = 13.5V, -15V Power Supply Rejection Ratio Large-Signal Voltage Gain Maximum Output Voltage Swing Slew Rate Supply Current per Amplifier
VS = 15V, - 40C TA 85C for I grades, unless otherwise noted.
SYMBOL PARAMETER VOS VOS T IOS IB AVOL CMRR PSRR Input Offset Voltage Input Offset Voltage Drift (Note 5) Input Offset Current Input Bias Current Large-Signal Voltage Gain VO = 10V, RL = 5k VS = 5V, 0V to 18V CONDITIONS LT2078 LT2079 LT2078 LT2079
q q q q q q q q q q q
LT2078AI/LT2079AI MIN TYP MAX 90 100 0.5 0.6 0.07 7 200 92 96 11.0 700 110 110 13.5 52 80 430 500 1.8 3.0 0.70 10
LT2078I/LT2079I MIN TYP MAX 120 130 0.6 0.7 0.1 7 150 88 92 11.0 700 110 110 13.5 54 95 600 700 2.5 3.8 1.0 12
UNITS V V V/C V/C nA nA V/mV dB dB V A
Common Mode Rejection Ratio VCM = 13V, -14.9V Power Supply Rejection Ratio Maximum Output Voltage Swing RL = 5k
IS
Supply Current per Amplifier
4
LT 2078/LT 2079
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER VOS VOS T IOS IB AVOL CMRR PSRR Input Offset Voltage Input Offset Voltage Drift (Note 5) Input Offset Current Input Bias Current Large-Signal Voltage Gain Common Mode Rejection Ratio Power Supply Rejection Ratio Maximum Output Voltage Swing IS Supply Current per Amplifier VO = 10V, RL = 5k VCM = 13V, -15V VS = 5V, 0V to 18V RL = 5k CONDITIONS LT2078 LT2079 LT2078 LT2079
VS = 15V, 0C TA 70C, unless otherwise noted (Note 6).
LT2078AC/LT2079AC MIN TYP MAX
q q q q q q q q q q q
LT2078C/LT2079C MIN TYP MAX 90 100 0.6 0.7 0.06 6 250 92 95 11.0 1200 112 112 13.6 50 85 460 540 2.5 3.8 0.50 11
UNITS V V V/C V/C nA nA V/mV dB dB V A
70 80 0.5 0.6 0.06 6 300 95 98 11.0 1200 112 112 13.6 49
330 410 1.8 3.0 0.35 9
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The q 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.
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 -300V. 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 - 40C and 85C. I-grade parts are guaranteed.
TYPICAL PERFORMANCE CHARACTERISTICS
Distribution of Offset Voltage Drift with Temperature
25 VS = 5V, 0V VCM = 0.1V 80 LT2078'S 25 LT2079'S = 260 OP AMPS
OFFSET CURRENT (pA)
INPUT BIAS CURRENT (nA)
20
PERCENT OF UNITS (%)
15
BIAS CURRENT (nA)
10
5
0 -2 0 1 -1 2 OFFSET VOLTAGE DRIFT WITH TEMPERATURE (V/C)
LT2078/79 * TPC01
UW
Input Bias and Offset Currents vs Temperature
100 VS = 5V, 0V TO 15V IOS
Input Bias Current vs Common Mode Voltage
0 VS = 5V, 0V -2 -4 -6 -8 -10 -12 -1 0 1 2 3 COMMON MODE VOLTAGE (V) 4 TA = 125C TA = -55C TA = 25C
50
0
-5 IB -6
-7 -50 -25
50 25 0 75 TEMPERATURE (C)
100
125
LT2078/79 * TPC02
LT2078/79 * TPC03
5
LT2078/LT 2079 TYPICAL PERFORMANCE CHARACTERISTICS
0.1Hz to 10Hz Noise
TA = 25C VS = 2.5V
NOISE VOLTAGE (0.4V/DIV)
NOISE VOLTAGE (0.4V/DIV)
CHANNEL A
VOLTAGE NOISE DENSITY (nV/Hz) CURRENT NOISE DENSITY (fA/Hz)
CHANNEL B
0
2
6 4 TIME (SEC)
10Hz Voltage Noise Distribution
35 OFFSET VOLTAGE CHANGE (V) 30 TA = 25C VS = 2.5V
10 5 0 -5
CHANGE IN OFFSET VOLTAGE (V)
PERCENT OF UNITS
25 20 15 10 5 0 25 35 30 VOLTAGE NOISE DENSITY (nV/Hz) 40
Minimum Supply Voltage
100 0 -100 -200 -300 -400 70C 0C 25C NONFUNCTIONAL -55C V - = 0V -0.1V VCM 0.4V 125C 1000
INPUT OFFSET VOLTAGE (V)
100
ISINK = 100A ISINK = 10A VS = 5V, 0V
OUTPUT VOLTAGE SWING (V)
SATURATION VOLTAGE (mV)
-500
0
2 3 1 POSITIVE SUPPLY VOLTAGE (V)
LT2078/79 * TPC10
6
UW
8
LT2078/79 * TPC04 LT2078/79 * TPC07
0.01Hz to 10Hz Noise
1000
Noise Spectrum
TA = 25C VS = 2.5V (AT VS = 15V VOLTAGE NOISE IS 4% LESS CURRENT NOISE IS UNCHANGED)
TA = 25C VS = 2.5V
300
CURRENT NOISE
CHANNEL A 0.4V
100 VOLTAGE NOISE 30 1/f CORNER 0.7Hz 10 0.1 1 100 10 FREQUENCY (Hz) 1000
CHANNEL B
10
0
20
60 40 TIME (SEC)
80
100
LT2078/79 * TPC05
LT2078/79 * TPC06
Long Term Stability of Two Representative Units (LT2078)
15 TA = 25C, VS = 5V, 0V VCM = 0.1V 1A 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 1 2 3 TIME (MONTHS) 4 5
Warm-Up Drift
TA = 25C VS = 15V WARM UP DRIFT AT VS = 5V, 0V IS IMMEASURABLY LOW
2B
1B -10 -15 2A
LT2079 LT2078
0
1
2
3
LT2078/79 * TPC09
TIME AFTER POWER-ON (MINUTES)
LT2078/79 * TPC08
Output Saturation vs Temperature vs Sink Current
V+
ISINK = 2mA ISINK = 1mA
Output Voltage Swing vs Load Current
125C V+ - 1 V+ - 2 -55C 25C
10
ISINK = 1A NO LOAD RL = 5k TO GND
V- + 2 125C V- + 1 25C
1 -50 -25
0 25 50 75 TEMPERATURE (C)
100
125
-55C V- 0.1 1 10 0.01 SOURCING OR SINKING LOAD CURRENT (mA)
LT2078/79 * TPC11.5
LT2078/79 * TPC11
LT 2078/LT 2079 TYPICAL PERFORMANCE CHARACTERISTICS
Gain, Phase vs Frequency
30 PHASE MARGIN 58 20 100
5V, 0V 10 PHASE MARGIN 46
140 160 5V, 0V 15V 180 200
80 60 40 20 0 VS = 5V, 0V
VOLTAGE GAIN (V/V)
VOLTAGE GAIN (dB)
VOLTAGE GAIN (dB)
0
-10 10 30 100 300 FREQUENCY (kHz) 1000
Slew Rate, Gain Bandwidth Product and Phase Margin vs Temperature
SLEW RATE (V/ s)
0.12 0.10 0.08 0.06 0.04 SLEW = 15V
80 60 40 20 0 1 10 100 1k 10k FREQUENCY (Hz) 100k 1M TA = 25C VS = 2.5V VIN = 3VP-P RL = 10k
OVERSHOOT (%)
M = 15V M = 5V, 0V
65 55 45
CHANNEL SEPARATION (dB)
SLEW = 5V, 0V
GAIN BANDWIDTH PRODUCT (kHz)
240 220 200 180
GBW = 15V
GBW = 5V, 0V fO = 20kHz 50 25 0 75 TEMPERATURE (C) 100 125
160 -50 -25
Undistorted Output Swing vs Frequency
PEAK-TO-PEAK OUTPUT SWING, VS = 15V (V)
30
COMMON MODE REJECTION RATIO (dB)
POWER SUPPLY REJECTION RATIO (dB)
VS = 15V RL 100k VS = 5V, 0V RL 100k VS = 5V, 0V RL 1k
20
10 TA = 25C LOAD RL, TO GND 0 0.01 1 10 FREQUENCY (kHz)
UW
15V VS = 15V RL = 30k
Voltage Gain vs Frequency
140 120 100 VS = 15V TA = 25C
10M
Voltage Gain vs Load Resistance
VS = 15V VS = 5V, 0V 125C 25C -55C
120
PHASE SHIFT (DEG)
1M
-55C 25C 125C
-20 0.01 0.1
1
10 100 1k 10k 100k 1M FREQUENCY (Hz)
LT2078/79 * TPC13
100k 100
1k 10k 100k LOAD RESISTANCE TO GROUND ()
1M
LTC2078/79 TPC12
LT2078/79 * TPC14
Channel Separation vs Frequency
120 100
120 100 80 60
Capacitive Load Handling
TA = 25C VS = 5V, 0V
75
PHASE MARGIN (DEG)
PEAK-TO-PEAK OUTPUT SWING, VS = 5V, 0V (V)
AV = 1
AV = 5 40 20 0 10 100 1000 CAPACITIVE LOAD (pF) 10000
LT2078/79 * TPC17
AV = 10
LT2078/79 * TPC15
LT2078/79 * TPC16
Common Mode Rejection Ratio vs Frequency
120 TA = 25C 100 VS = 15V 80 VS = 5V, 0V 60 40 20 0 10 100 1k 10k FREQUENCY (Hz) 100k 1M
Power Supply Rejection Ratio vs Frequency
120 100 80 60 40 20 0 0.1 NEGATIVE SUPPLY
5 4 3 2 1 0 100
LT2078/79 * TPC18
POSITIVE SUPPLY
TA = 25C VS = 2.5V + 1VP-P SINE WAVE 1 10 100 1k 10k FREQUENCY (Hz) 100k 1M
LT2078/79 * TPC19
LT2078/79 * TPC20
7
LT2078/LT 2079 TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs Temperature
55
SUPPLY CURRENT PER AMPLIFIER (A)
50
COMMON MODE RANGE (V)
OUTPUT IMPEDANCE ()
VS = 15V 45 40 35 30 25 -50 -25 VS = 5V, 0V
50 25 75 0 TEMPERATURE (C)
Small-Signal Transient Response VS = 5V, 0V
20mV/DIV
20mV/DIV
0V
0V
20mV/DIV
AV = 1 10s/DIV CL = 15pF INPUT 50mV TO 150mV
Large-Signal Transient Response VS = 5V, 0V
1V/DIV
5V/DIV
AV = 1, NO LOAD 50s/DIV INPUT PULSE 0V TO 3.8V
LT2078/79 * TPC27
8
UW
100
LT2078/79 * TPC21 LT2078/79 * TPC24
Common Mode Range vs Temperature
V+ V+ - 1 V+ - 2 V- + 1 V- V- - 1 -50 -25 V + = 2.5V TO 18V V - = 0V TO -18V
Closed-Loop Output Impedance
1k AV = 100 AV = 10 10 AV = 1 1
100
0.1
125
0 25 50 75 TEMPERATURE (C) 100 125
10
100 1k 10k FREQUENCY (Hz)
100k
LT2078/79 * TPC23
LT2078/79 * TPC22
Small-Signal Transient Response VS = 2.5V
Small-Signal Transient Response VS = 15V
0V
AV = 1 CL = 15pF
10s/DIV
LT2078/79 * TPC25
AV = 1 CL = 15pF
10s/DIV
LT2078/79 * TPC26
Large-Signal Transient Response VS = 15V
0V
0V
AV = 1 NO LOAD
100s/DIV
LT2078/79 * TPC28
LT 2078/LT 2079
SI PLIFIED SCHEMATIC W
2.2k Q16 Q39 Q9 C2 175pF Q7 Q8 Q10 Q17 Q20 Q34 6.2k 6.2k 1.35k 10k Q38 30 4A 5.35k Q23 V+ Q45 Q51 Q55 Q43 700k V-
LT2078/79 * SIMPLIFIED SCHEM
IN -
IN +
W
1/2 LT2078, 1/4 LT2079
V+
10k
10k
5.6k
1.3k
3.6k Q54 1 1
5k Q53 2 Q47
11.5k
12.5k
Q5
Q6
Q14
Q15
Q32
Q52 Q46
Q3 Q4 Q24
Q29
Q37 Q30 1 3 Q25 3k Q35 Q26 C4 4pF 2.9k 30 OUT Q44 V
+
V- Q40 Q41
Q12 4 Q11 1
8.6k
C1 50pF
Q27 600 Q1 Q21 Q2 Q22 Q28 V+
C5 2.5pF 150k C3 40pF Q19 Q50 Q31 Q36 J1 Q33 Q42 Q48 Q49
Q18
600
9.1k
700k
9
LT2078/LT 2079
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 (=2V/V), at 9V the offset voltage change will be 8V. Similarly, VS = 2.5V, VCM = 0V is equivalent to a common mode voltage change of 2.4V or a VOS change of 7V if CMRR = 110dB (3V/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 0.1F). 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.
5V R
-
1mV
99R 100mV
+
LT2078/79 * F02a
Figure 1a. Gain 100 Amplifier
10
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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 300A (150A 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
-
1mV
+
OUTPUT SATURATION 3.5mV
LT2078/79 * F02b
Figure 1b. Voltage Follower
LT 2078/LT 2079
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 25C), 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 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 UNITS V V V/C nA nA dB dB
LT2078 LT2079 Temperature Coefficient VOS Average Noninverting IB Match of Noninverting IB CMRR Match PSRR Match
4V
4V
2V
2V
0V
0V
6VP-P INPUT -1V TO 5V
1ms/DIV
LT2078/79 * F01a
1ms/DIV OP-90 EXHIBITS OUTPUT PHASE REVERSAL
LT2078/79 * F01b
Figure 2. Voltage Follower with Input Exceeding the Negative Common Mode Range (VS = 5V, 0V)
U
W
U
U
4V
2V
0V
1ms/DIV LT2078/LT2079 NO PHASE REVERSAL
LT2078/79 * F01C
11
LT2078/LT 2079
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, 70V maximum offset voltage implies that mismatch cannot be more than 140V. 95dB (= 17.5V/V) CMRR means that worst-case CMRR match is 89dB (= 35V/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) OUTPUT (V) INPUT (mV) VS = 5V, 0V 200s/DIV
LT2078/79 * F03
2 0
INPUT (mV)
0
-100
Figure 3. Comparator Rise Response Time to 10mV, 5mV, 2mV Overdrives
TYPICAL APPLICATIONS
Micropower, 10ppm/C, 5V Reference
2M LT1034BC-1.2 220k 5VOUT 120k 3 1M 9V
+ -
8 1 1M 6
1/2 LT2078 2 4 -9V 510k 1%
-
1/2 LT2078 7 -5.000VOUT
LT2078/79 * TA03
510k
5
+
160k 1%
20k
SUPPLY CURRENT = 9V BATTERY = 115A -9V BATTERY = 85 A OUTPUT NOISE = 36VP-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
U
W
U
U
U
4
2
0 100
0
VS = 5V, 0V
200s/DIV
LT2078/79 * F04
Figure 4. Comparator Fall Response Time to 10mV, 5mV, 2mV Overdrives
Gain of 10 Difference Amplifier
10M 3V 1M -IN 1M +IN
-
1/2 LT2078 OUTPUT 0.0035V TO 2.4V
LT2078/79 * TA04
+
10M
BANDWIDTH= 20kHz OUTPUT OFFSET= 0.7mV OUTPUT NOISE= 80 VP-P (0.1Hz TO 10Hz) 260 VRMS 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
TYPICAL APPLICATIONS
Picoampere Input Current, Triple Op Amp Instrumentation Amplifier with Bias Current Cancellation
-IN 3
+
1/4 LT2079 1
R2 1M R1 1M RG 200k 9 R3 9.1M
+IN 10M -IN
2
-
2R 20M 6
-
1/4 LT2079 7
R1 1M 10 R2 1M
+IN
5
+
9V 4 14
R 10M 2R 20M
12
+ -
1/4 LT2079 13 11
GAIN = 1 + 2R1 R3 = 100 FOR VALUES SHOWN RG R2 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
Half-Wave Rectifier
2M 3V 2M INPUT 1M
-
1/2 LT2078 OUTPUT
+
VOMIN = 6mV NO DISTORTION TO 100Hz
1.8V -1.8V
1.8V 0V
LT2078/79 * TA07
1.11k
10k 3V TO 18V 2
- +
4 1 6 1
1/4 LT2079 3 11
IN ERROR DUE TO SWITCH ON RESISTANCE, LEAKAGE CURRENT, NOISE AND TRANSIENTS ARE ELIMINATED
U
85V, -100V Common Mode Range Instrumentation Amplifier (AV = 10)
1M 9V 10M 2 10M
- +
8 1 100k 6
1/2 LT2078 3 4 -9V
-
1/2 LT2078 7 OUTPUT 8V TO -9V
LT2078/79 * TA06
-
1/4 LT2079 8 OUTPUT 4mV TO 8.2V
LT2078/79 * TA05
100k
5
+
1M
+
R3 9.1M
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
(
)
Absolute Value Circuit (Full-Wave Rectifier)
200k 5V 200k INPUT 2 3.5V 0V 1 1N4148 4 6 5
- +
8
1/2 LT2078 3.5V 3
+
1/2 LT2078 7 OUTPUT
-
LT2078/79 * TA08
-3.5V VOMIN = 4mV NO DISTORTION TO 100Hz
Programmable Gain Amplifier (Single Supply)
100k 1M
3V TO 18V 11 13 A 2 4 9 12
-
1/4 LT2079 14 OUT
-
1/4 LT2079 7 9 3B
+
5
LT2078/79 * TA09
+
-
1/4 LT2079 88
C CD4016B 13 5 6
7 GAIN PIN 13 1000 HIGH 100 LOW 10 LOW
10
+
CD4016B PIN 5 LOW HIGH LOW
PIN 6 LOW LOW HIGH
13
LT2078/LT 2079
TYPICAL APPLICATIONS
Single Supply, Micropower, Second Order Lowpass Filter with 60Hz Notch
0.02F 27.6k 0.1% IN 27.6k 0.1% 5V 8 1 6 2.64M 0.1% 2.64M 0.1% 2000pF 0.5% 120k 5% 100pF fC = 40Hz Q = 30 1000pF 0.5% 1000pF 0.5%
LT2078/79 * TA10
Y INPUT (5mV TO 50V)
505k 0.1% 9V
1/4 LT2079
7 30k 5%
30k 5%
14
1/4 LT2079 12 10k GAIN
11 -1.5V TO -9V X INPUT (5mV TO 50V) 505k 0.1% 220pF
499k 0.5%
1/4 LT2079
1 30k 5%
INPUT 510k
9V
1M
680k
1N914 1000pF
510k Q6 2N4393 VSET VOUT VIN
14
+
5
-
6
4 7 1M Q5
1/4 LT2079 11
-9V
BIPOLAR SYMMETRY IS EXCELLENT VSET BECAUSE ONE DEVICE, Q2, * 1% FILM SETS BOTH LIMITS ** RATIO MATCH 0.05% SUPPLY CURRENT 240A Q2, Q3, Q4, Q5 CA3096 TRANSISTOR ARRAY BANDWIDTH = 150kHz
+
+
1M
1N914
1/4 LT2079 10 510k
12
-
-
Q1 2N4393
+
3
-
+
3
Micropower Dead Zone Generator
Q4 1M** 1M** 2 1M* Q2 1 1/4 LT2079 1M* GAIN 200k 8 1M** 13 1M** Q3 470k VSET DEAD ZONE CONTROL INPUT 0.4V TO 5V
9
+
-
2
Q2
Q4
10
-
9
1/4 LT2079
8
+
+
5
-
-
6
4
U
-
1/2 LT2078 7
3 0.01F 2
+ -
5.1M 1%
1/2 LT2078 4
5
+
OUTPUT TYPICAL OFFSET 600V
1.35M 0.1%
Micropower Multiplier/Divider
505k 0.1% Z INPUT (5mV TO 50V)
220pF
Q1
Q3
220pF 13 Q1,Q2, Q3, Q4 = MAT-04 TYPICAL LINEARITY = 0.01% OF FULL-SCALE OUTPUT (X)(Y) OUTPUT = , POSITIVE INPUTS ONLY (Z) X + Y+ Z + OUT 500k OUT POSITIVE SUPPLY CURRENT = 165A + 500k NEGATIVE SUPPLY CURRENT = 165A + BANDWIDTH (< 3VP-P SIGNAL): X AND Y INPUTS = 10kHz Z INPUT = 4kHz OUTPUT (5mV TO 8V)
lt2078/79 * TA11
1/4 LT2079
14
VOUT
LT2078/79 * TA12
LT 2078/LT 2079
TYPICAL APPLICATIONS
Lead-Acid Low-Battery Detector with System Shutdown
BATTERY OUTPUT 2M 1% 2M 1% 910k 5% 3 12V
PACKAGE DESCRIPTION
0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254)
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
0.016 - 0.050 0.406 - 1.270
0.010 - 0.020 x 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
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.
U
U
+
1/2 LT2078 1 LO = BATTERY LOW (IF VS < 10.90V)
2
-
5
+ -
8 7 LO = SYSTEM SHUTDOWN (IF VS < 10.05V)
1/2 LT2078 255k 1% 280k 1% LT1004-1.2
LT2078/79 * TA13
6
4
TOTAL SUPPLY CURRENT = 105A
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
8 0.189 - 0.197* (4.801 - 5.004) 7 6 5
0.053 - 0.069 (1.346 - 1.752) 0- 8 TYP
0.228 - 0.244 (5.791 - 6.197) 0.004 - 0.010 (0.101 - 0.254) 0.150 - 0.157** (3.810 - 3.988)
0.050 (1.270) BSC
1
2
3
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) 14 13 12 11 10 9 8
0.004 - 0.010 (0.101 - 0.254) 0.150 - 0.157** (3.810 - 3.988) 0.050 (1.270) TYP 0.228 - 0.244 (5.791 - 6.197)
S14 0695
1
2
3
4
5
6
7
15
LT2078/LT 2079
TYPICAL APPLICATION
Platinum RTD Signal Conditioner with Curvature Correction
3V (LITHIUM) 13k* 12.3k* 10k* 2 50k 5C TRIM 1k** 1k** 43.2k**
LT1004-1.2 1
RP 1k AT 0C
1F
1.21M* (SELECT AT 110C)
LT2078/79 * TA14
RELATED PARTS
PART NUMBER DESCRIPTION LT1178/LT1179 Dual/Quad 17A Max, Single Supply Precision Op Amps LT1211/LT1212 14MHz, 7V/s Single Supply Dual and Quad Precision Op Amps COMMENTS 70V VOS Max and 2.5V/C Drift Max, 85kHz GBW, 0.04V/s Slew Rate, Input/Output Common Mode Includes Ground 275V VOS Max, 6V/C Drift Max Input Voltage Range Includes Ground
LT1490/LT1491 Dual/ Quad Micropower Rail-to-Rail Input and Output Op Amps Single Supply Input Range: -0.4V to 44V, Micropower 50A Amplifier, Rail-to-Rail Input and Output, 200kHz GBW LT2178/LT2179 Dual/Quad 17A Max, Single Supply Precision Op Amps SO-8 and 14-Lead Standard Pinout, 70V VOS Max, 85kHz GBW
16
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977
+
RP = ROSEMOUNT 118MF ** = TRW MAR-6 0.1% * = 1% METAL FILM
1k**
5
-
U
1F 5k 220C TRIM
8
+ -
3
1/2 LT2078 4
6
1/2 LT2078
7
0.02V TO 2.2VOUT = 2C TO 220C 0.1C
LT/GP 1096 7K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1996

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