LINER LTC1151C

LTC1151
Dual ±15V Zero-Drift
Operational Amplifier
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DESCRIPTIO
FEATURES
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Maximum Offset Voltage Drift: 0.05µV/°C
High Voltage Operation: ±18V
No External Components Required
Maximum Offset Voltage: 5µV
Low Noise: 1.5µVP-P (0.1Hz to 10Hz)
Minimum Voltage Gain: 125dB
Minimum CMRR: 106dB
Minimum PSRR: 110dB
Low Supply Current: 0.9mA/Amplifier
Single Supply Operation: 4.75V to 36V
Input Common-Mode Range Includes Ground
Typical Overload Recovery Time: 20ms
The LTC1151 is a high voltage, high performance dual
zero-drift operational amplifier. The two sample-and-hold
capacitors per amplifier required externally by other chopper amplifiers are integrated on-chip. The LTC1151 also
incorporates proprietary high voltage CMOS structures
which allow operation at up to 36V total supply voltage.
The LTC1151 has a typical offset voltage of 0.5µV,
drift of 0.01µV/°C, 0.1Hz to 10Hz input noise voltage of
1.5µVP-P, and a typical voltage gain of 140dB. It has a slew
rate of 3V/µs and a gain-bandwidth product of 2.5MHz
with a supply current of 0.9mA per amplifier. Overload
recovery times from positive and negative saturation are
3ms and 20ms, respectively.
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APPLICATI
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The LTC1151 is available in a standard 8-lead plastic DIP
package as well as a 16-lead wide body SO. The LTC1151
is pin compatible with industry-standard dual op amps
and runs from standard ±15V supplies, allowing it to plug
in to most standard bipolar op amp sockets while offering
significant improvement in DC performance.
Strain Gauge Amplifiers
Instrumentation Amplifiers
Electronic Scales
Medical Instrumentation
Thermocouple Amplifiers
High Resolution Data Acquisition
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TYPICAL APPLICATI
±15V Dual Thermocouple Amplifier
51Ω 100Ω*
240k
Noise Spectrum
15V
60
–
VIN K 7
+
LT1025
3
VO
GND
4
R–
5
2k
5
–
8
1/2
LTC1151
7
OUTPUT A
100mV/°C
+
240k
51Ω 100Ω*
TYPE K
470k
2
+
40
30
20
10
–15V
–
NOISE VOLTAGE (nV/√Hz)
6
15V
50
0.1µF
0.1µF
2k
3
1/2
LTC1151
+
0
0.1µF
–
OUTPUT B
100mV/°C
1
1
10
100
1k
FREQUENCY (Hz)
10k
1151 TA02
4
0.1µF
TYPE K
* FULL SCALE TRIM: TRIM FOR 10.0V OUTPUT
WITH THERMOCOUPLE AT 100°C
–15V
1151 TA01
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LTC1151
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ABSOLUTE
RATI GS
(Note 1)
Total Supply Voltage (V + to V –) ............................. 36V
Input Voltage (Note 2) .......... (V + + 0.3V) to (V – – 0.3V)
Output Short Circuit Duration ......................... Indefinite
Burn-In Voltage ...................................................... 36V
Operating Temperature Range
LTC1151C............................................... 0°C to 70°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
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PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
TOP VIEW
OUT A 1
8
V+
–IN A 2
7
OUT B
+IN A 3
6
–IN B
V– 4
5
+IN B
LTC1151CN8
ORDER PART
NUMBER
TOP VIEW
NC
1
16
NC
NC
2
15
NC
OUT A
3
14
V+
–IN A
4
13
OUT B
+IN A
5
12
–IN B
V–
6
11
+IN B
NC
7
10
NC
NC
8
9
NC
N8 PACKAGE
8-LEAD PLASTIC DIP
LTC1151CS
S PACKAGE
16-LEAD PLASTIC SOL
TJMAX = 110°C, θJA = 130°C/ W
TJMAX = 110°C, θJA = 200°C/ W
ELECTRICAL CHARACTERISTICS
VS = ±15V, TA = Operating Temperature Range, unless otherwise specified.
PARAMETER
CONDITIONS
Input Offset Voltage
TA = 25°C (Note 3)
Average Input Offset Drift
(Note 3)
MIN
●
Long Term Offset Voltage Drift
Input Offset Current
LTC1151C
TYP
MAX
±0.5
±5
±0.01
±0.05
50
TA = 25°C
TA = 25°C
µV
µV/°C
nV/√mo
±20
±200
±0.5
pA
nA
±15
±100
±0.5
pA
nA
●
Input Bias Current
UNITS
●
Input Noise Voltage
RS = 100Ω, 0.1Hz to 10Hz
RS = 100Ω, 0.1Hz to 1Hz
1.5
0.5
µVP-P
µVP-P
Input Noise Current
f = 10Hz (Note 4)
2.2
fA/√Hz
Input Voltage Range
Positive
Negative
●
●
12
–15
13.2
–15.3
V
V
Common-Mode Rejection Ratio
VCM = V – to 12V
●
106
130
dB
Power Supply Rejection Ratio
VS = ±2.375V to ±16V
●
110
130
dB
Large-Signal Voltage Gain
RL = 10k, VOUT = ±10V
●
125
140
dB
2
LTC1151
ELECTRICAL CHARACTERISTICS
VS = ±15V, TA = Operating Temperature Range, unless otherwise specified.
PARAMETER
CONDITIONS
Maximum Output Voltage Swing
RL = 10k, TA = 25°C
RL = 10k
RL = 100k
Slew Rate
MIN
●
RL = 10k, CL = 50pF
No Load, TA = 25°C
No Load
MAX
UNITS
±13.5
±14.50
+10.5/–13.5
±14.95
Gain-Bandwidth Product
Supply Current per Amplifier
LTC1151C
TYP
2.5
V/µs
2
MHz
0.9
●
Internal Sampling Frequency
V
V
V
1.5
2.0
mA
mA
1000
Hz
VS = 5V, TA = Operating Temperature Range, unless otherwise specified.
Input Offset Voltage
TA = 25°C (Note 3)
Average Input Offset Drift
(Note 3)
●
Long Term Offset Voltage Drift
Input Offset Current
±0.05
±5
±0.01
±0.05
50
TA = 25°C
µV
µV/°C
nV/√mo
±10
100
50
pA
Input Bias Current
TA = 25°C
±5
Input Noise Voltage
RS = 100Ω, 0.1Hz to 10Hz
RS = 100Ω, 0.1Hz to 1Hz
2.0
0.7
µVP-P
µVP-P
Input Noise Current
f = 10Hz (Note 4)
1.3
fA/√Hz
Input Voltage Range
Positive
Negative
2.7
0
3.2
– 0.3
V
V
Common-Mode Rejection Ratio
VCM = 0V to 2.7V
110
Power Supply Rejection Ratio
VS = ±2.375V to ±16V
●
110
130
dB
Large-Signal Voltage Gain
RL = 10k, VOUT = 0.3V to 4.5V
●
115
140
dB
Maximum Output Voltage Swing
RL = 10k to GND
RL = 100k to GND
4.85
4.97
V
V
Slew Rate
RL = 10k, CL = 50pF
1.5
V/µs
1.5
MHz
Gain Bandwidth Product
Supply Current per Amplifier
No Load, TA = 25°C
dB
0.5
●
Internal Sampling Frequency
The • denotes the specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which life of
the device may be impaired.
Note 2: Connecting any terminal to voltages greater than V + or less than
V – may cause destructive latch-up. It is recommended that no sources
operating from external supplies be applied prior to power-up of the
LTC1151.
pA
1.0
1.5
750
mA
mA
Hz
Note 3: These parameters are guaranteed by design. Thermocouple
effects preclude measurement of these voltage levels in high speed
automatic test systems. VOS is measured to a limit determined by test
equipment capability.
Note 4: Current Noise is calculated from the formula:
IN = √(2q • Ib)
where q = 1.6 × 10 –19 Coulomb.
3
LTC1151
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TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Supply Voltage
2.5
15
2.00
VS = ±15V
2.0
1.5
1.0
0.5
0
4
8
12 16 20 24 28 32
TOTAL SUPPLY VOLTAGE (V)
TA = 25°C
10
COMMON-MODE RANGE (V)
TOTAL SUPPLY CURRENT (mA)
TOTAL SUPPLY CURRENT (mA)
TA = 25°C
1.75
1.50
10
0
20
30
60
40
50
TEMPERATURE (˚C)
0
70
–3
VOUT = V +
ISINK
120
20
15
10
–15
VS = ±15V
RL = 10k
80
60
20
0
0
100
12 16 20 24 28 32 36
8
TOTAL SUPPLY VOLTAGE, V + TO V – (V)
100
40
5
–12
VS = ±15V
140
CMRR (dB)
OUTPUT VOLTAGE (VP-P)
VOUT = V –
ISOURCE
4
±10.0 ±12.5 ±15.0
CMRR vs Frequency
25
–9
±7.5
160
TA = 25°C
–6
±5.0
1151 G03
30
0
±2.5
SUPPLY VOLTAGE (V)
Undistorted Output Swing vs
Frequency
6
2
–5
1151 G02
Output Short-Circuit Current vs
Supply Voltage
4
0
–15
1.25
36
5
–10
1151 G01
SHORT-CIRCUIT OUTPUT CURRENT (mA)
Common-Mode Input Voltage
Range vs Supply Voltage
Supply Current vs Temperature
1k
10k
100k
FREQUENCY (Hz)
1M
1
10
100
1k
FREQUENCY (Hz)
10k
1151 G05
1151 G04
Gain and Phase vs Frequency
100k
1151 G06
PSRR vs Frequency
Gain and Phase vs Frequency
160
135
80
PHASE
45
40
0
60
GAIN
45
40
0
20
20
100
80
NEGATIVE
SUPPLY
60
40
–45
–45
20
0
0
POSITIVE
SUPPLY
120
90
PHASE (DEG)
GAIN
PHASE (DEG)
60
VS = ±15V
140
135
PHASE
90
GAIN (dB)
80
GAIN (dB)
VS = ±2.5V
CL = 100pF
100
PSRR (dB)
VS = ±15V
CL = 100pF
100
0
10
100
1k
10k 100k
FREQUENCY (Hz)
1M
10M
1151 G07
4
10
100
1k
10k 100k
FREQUENCY (Hz)
1M
10M
1151 G08
1
10
100
1k
FREQUENCY (Hz)
10k
100k
1151 G09
LTC1151
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TYPICAL PERFOR A CE CHARACTERISTICS
Input Bias Current Magnitude vs
Supply Voltage
Input Bias Current Magnitude vs
Temperature
18
1000
VCM = 0
VS = ±15V
60
TA = 25°C
VCM = 0V
100
10
12
9
6
3
1
–50
25
50
75
0
TEMPERATURE (°C)
0
100 125
30
–IB
15
0
–15
+IB
–30
–45
0
–25
VS = 15V
TA = 25°C
45
INPUT BIAS CURRENT (pA)
INPUT BIAS CURRENT (pA)
15
±2
±4 ±6 ±8 ±10 ±12 ±14 ±16
SUPPLY VOLTAGE (V)
–60
–15
–5
5
10
–10
0
INPUT COMMON-MODE VOLTAGE (V)
1151 G11
1151 G10
15
1151 G12
0.1Hz to 10Hz Noise
VS = ±15V
TA = 25°C
1µV
10s
1s
1151 G13
Large-Signal Transient Response
Negative Overload Recovery
5V/DIV
Small-Signal Transient Response
5
0
2V/DIV
50mV/DIV
0
2V/DIV
INPUT BIAS CURRENT (pA)
Input Bias Current vs
Input Common-Mode Voltage
2ms/DIV
VS = ±15V, AV = 1
CL = 100pF, RL = 10k
1151 G14
VS = ±15V, AV = 1
CL = 100pF, RL = 10k
2ms/DIV
1151 G15
2ms/DIV
VS = ±15V, AV = –100
NOTE: POSITIVE OVERLOAD RECOVERY IS
TYPICALLY 3ms.
1151 G16
5
LTC1151
TEST CIRCUITS
Offset Voltage Test Circuit
DC-10Hz Noise Test Circuit
100pF
1M
100k
1k
2
–
V+
7
2
6
LTC1151
3
OUTPUT
10Ω
7
–
LTC1151
+
5V
5V
RL
4
3
+
2
6
4
V–
–5V
1151 TC01
800k
0.02µF
3
–
8
1/2
LT1057
+4
–5V
0.04µF
6
800k
5
–
1/2
LT1057
1
800k
7
OUTPUT
+
0.01µF
1151 TC02
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APPLICATI
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ACHIEVING PICOAMPERE/MICROVOLT PERFORMANCE
Picoamperes
In order to realize the picoampere level of accuracy of the
LTC1151 proper care must be exercised. Leakage currents
in circuitry external to the amplifier can significantly degrade performance. High quality insulation should be used
(e.g., Teflon); cleaning of all insulating surfaces to remove
fluxes and other residues will probably be necessary,
particularly for high temperature performance. Surface
coating may be necessary to provide a moisture barrier in
high humidity environments.
Board leakage can be minimized by encircling the input
connections with a guard ring operated at a potential close
to that of the inputs: in inverting configurations the guard
ring should be tied to ground; in noninverting connections
to the inverting input. Guarding both sides of the printed
circuit board is required. Bulk leakage reduction depends
on the guard ring width.
Microvolts
Thermocouple effects must be considered if the LTC1151’s
ultra low drift is to be fully utilized. Any connection of
dissimilar metals forms a thermoelectric junction producing an electric potential which varies with temperature
(Seebeck effect). As temperature sensors, thermocouples
exploit this phenomenon to produce useful information. In
low drift amplifier circuits the effect is a primary source of
error.
6
Connectors, switches, relay contacts, sockets, resistors,
solder, and even copper wire are all candidates for thermal
EMF generation. Junctions of copper wire from different
manufacturers can generate thermal EMFs of 200nV/°C;
four times the maximum drift specification of the LTC1151.
Minimizing thermal EMF-induced errors is possible if
judicious attention is given to circuit board layout and
component selection. It is good practice to minimize the
number of junctions in the amplifier’s input signal path.
Avoid connectors, sockets, switches, and relays where
possible. In instances where this is not possible, attempt
to balance the number and type of junctions so that
differential cancellation occurs. Doing this may involve
deliberately introducing junctions to offset unavoidable
junctions.
Figure 1 is an example of the introduction of an unnecessary resistor to promote differential thermal balance.
Maintaining compensating junctions in close physical
proximity will keep them at the same temperature and
reduce thermal EMF errors.
When connectors, switches, relays and/or sockets are
necessary they should be selected for low thermal EMF
activity. The same techniques of thermally balancing and
coupling the matching junctions are effective in reducing
the thermal EMF errors of these components.
LTC1151
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APPLICATI
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NOMINALLY UNNECESSARY
RESISTOR USED TO
THERMALLY BALANCE
OTHER INPUT RESISTOR
LEAD WIRE/SOLDER
COPPER TRACE JUNCTION
PACKAGE-INDUCED OFFSET VOLTAGE
Package-induced thermal EMF effects are another important source of errors. They arise at the junctions formed
when wire or printed circuit traces contact a package lead.
Like all the previously mentioned thermal EMF effects,
they are outside the LTC1151’s offset nulling loop and
cannot be cancelled. The input offset voltage specification
of the LTC1151 is actually set by the package-induced
warm-up drift rather than by the circuit itself. The thermal
time constant ranges from 0.5 to 3 minutes, depending on
package type.
+
LTC1151
OUTPUT
–
RESISTOR LEAD, SOLDER,
COPPER TRACE JUNCTION
1151 F01
ALIASING
Figure 1. Extra Resistors Cancel Thermal EMF
Resistors are another source of thermal EMF errors. Table
1 shows the thermal EMF generated for different resistors.
The temperature gradient across the resistor is important,
not the ambient temperature. There are two junctions
formed at each end of the resistor and if these junctions are
at the same temperature, their thermal EMFs will cancel
each other. The thermal EMF numbers are approximate
and vary with resistor value. High values give higher
thermal EMF.
Table 1. Resistor Thermal EMF
RESISTOR TYPE
>1mV/°C
Carbon Composition
∼450µV/°C
Metal Film
∼20µV/°C
Wire Wound
Evenohm, Manganin
∼2µV/°C
For a complete discussion of the correction circuitry and
aliasing behavior, please refer to the LTC1051/LTC1053
data sheet.
LOW SUPPLY OPERATION
The minimum supply for proper operation of the LTC1151
is typically 4.0V (±2.0V). In single supply applications,
PSRR is guaranteed down to 4.7V (±2.35V) to ensure
proper operation at minimum TTL supply voltage of 4.75V.
THERMAL EMF/°C GRADIENT
Tin Oxide
Like all sampled data systems, the LTC1151 exhibits
aliasing behavior at input frequencies near the sampling
frequency. The LTC1151 includes a high frequency correction loop which minimizes this effect. As a result,
aliasing is not a problem for many applications.
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TYPICAL APPLICATI
S
High Voltage Instrumentation Amplifier
1k
V+
1M
1M
2
–
8
1/2
LTC1151
–IN
3
0.1µF
1
1k
6
+
+IN
5
–
1/2
LTC1151
+
4
7
VOUT
GAIN = 1000V/V
OUTPUT OFFSET < 5mA
0.1µF
V–
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 circuits as described herein will not infringe on existing patent rights.
1151 TA03
7
LTC1151
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TYPICAL APPLICATI
S
Bridge Amplifier with Active Common-Mode Suppression
15V
15V
49.9k
350Ω TRIM TO SET
BRIDGE OPERATING
CURRENT
0.1µF
–
1/2
LTC1151
350Ω
STRAIN
GAUGE
–
1/2
LTC1151
VOUT
AV = 100
+
499Ω
+
0.1µF
–15V
1151 TA04
390Ω
–15V
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PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
N8 Package, 8-Lead Plastic DIP
0.300 – 0.320
(7.620 – 8.128)
0.009 – 0.015
(0.229 – 0.381)
(
+0.025
0.325 –0.015
8.255
+0.635
–0.381
)
0.045 – 0.065
(1.143 – 1.651)
0.400
(10.160)
MAX
0.130 ± 0.005
(3.302 ± 0.127)
8
7
0.250 ± 0.010
(6.350 ± 0.254)
0.125
(3.175)
MIN
0.045 ± 0.015
(1.143 ± 0.381)
0.020
(0.508)
MIN
1
2
0.398 – 0.413
(10.109 – 10.490)
16
0.093 – 0.104
(2.362 – 2.642)
SEE NOTE
0.016 – 0.050
(0.406 – 1.270)
14
13
12
11
10
9
0.394 – 0.419
(10.007 – 10.643)
SEE NOTE
0.050
(1.270)
TYP
0.004 – 0.012
(0.102 – 0.305)
0.014 – 0.019
(0.356 – 0.482)
TYP
NOTE:
PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS.
THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS.
8
15
0.037 – 0.045
(0.940 – 1.143)
0° – 8° TYP
0.009 – 0.013
(0.229 – 0.330)
4
3
0.018 ± 0.003
(0.457 ± 0.076)
0.100 ± 0.010
(2.540 ± 0.254)
0.291 – 0.299
(7.391 – 7.595)
0.010 – 0.029 × 45°
(0.254 – 0.737)
5
0.065
(1.651)
TYP
S Package, 16-Lead SOL
0.005
(0.127)
RAD MIN
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Linear Technology Corporation
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LT/GP 0193 10K REV 0
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977
 LINEAR TECHNOLOGY CORPORATION 1993