LTC1049 Low Power Zero-Drift Operational Amplifier with Internal Capacitors Description Features n n n n n n n n n Low Supply Current: 200µA No External Components Required Maximum Offset Voltage: 10µV Maximum Offset Voltage Drift: 0.1µV/°C Single Supply Operation: 4.75V to 16V Input Common Mode Range Includes Ground Output Swings to Ground Typical Overload Recovery Time: 6ms Available in 8-Pin SO and PDIP Packages The LTC®1049 is a high performance, low power zero-drift operational amplifier. The two sample-and-hold capacitors usually required externally by other chopper stabilized amplifiers are integrated on the chip. Further, the LTC1049 offers superior DC and AC performance with a nominal supply current of only 200µA. The LTC1049 has a typical offset voltage of 2µV, drift of 0.02µV/°C, 0.1Hz to 10Hz input noise voltage of 3µVP-P and typical voltage gain of 160dB. The slew rate is 0.8V/µs with a gain bandwidth product of 0.8MHz. Applications n n n n n n Overload recovery time from a saturation condition is 6ms, a significant improvement over chopper amplifiers using external capacitors. 4mA to 20mA Current Loops Thermocouple Amplifiers Electronic Scales Medical Instrumentation Strain Gauge Amplifiers High Resolution Data Acquisition The LTC1049 is available in a standard 8-pin plastic dual in line, as well as an 8-pin SO package. The LTC1049 can be a plug-in replacement for most standard op amps with improved DC performance and substantial power savings. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical Application Single Supply Thermocouple Amplifier 0.068µF VIN = 5V 246k 1k 2 2 K LT ®1025A GND 4 R– 5 7 – + TYPE K 3 – 7 LTC1049 + 6 VOUT = 0V TO 4V FOR 0°C TO 400°C 4 0.1µF SUPPLY CURRENT = 280µA LTC1049 • TA01 1049fb 1 LTC1049 Absolute Maximum Ratings (Note 1) Total Supply Voltage (V + to V –).................................18V Input Voltage (Note 2).............(V+ + 0.3V) to (V – – 0.3V) Output Short-Circuit Duration........................... Indefinite Operating Temperature Range..................–40°C to 85°C Storage Temperature Range...................–65°C to 150°C Lead Temperature (Soldering, 10 sec).................... 300°C Package/order information TOP VIEW NC 1 8 NC –IN 2 7 V+ +IN 3 6 OUT V– 4 5 NC ORDER PART NUMBER LTC1049CN8 NC 1 –IN 2 +IN 3 V– N8 PACKAGE 8-LEAD PDIP TJMAX = 110°C, θJA = 130°C/W LTC1049CJ8 J8 PACKAGE 8-LEAD CERDIP TJMAX = 150°C, θJA = 100°C/W OBSOLETE PACKAGE ORDER PART NUMBER TOP VIEW 4 – + 8 NC 7 V+ 6 OUT 5 NC LTC1049CS8 S8 PART MARKING S8 PACKAGE 8-LEAD PLASTIC SO 1049 TJMAX = 110°C, θJA = 200°C/W Consider the N8 Package as an Alternate Source Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges. Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = ±5V, unless noted. PARAMETER CONDITIONS Input Offset Voltage Average Input Offset Drift Long Term Offset Voltage Drift Input Offset Current (Note 3) (Note 3) MIN l TYP MAX UNITS ±2 ±0.02 50 ±30 ±10 ±0.1 µV µV/°C nV√mo pA pA pA pA µVP-P µVP-P fA√Hz dB dB dB V V V V/µs MHz µA µA Hz l ±15 Input Bias Current l Input Noise Voltage Input Noise Current Common Mode Rejection Ratio Power Supply Rejection Ratio Large-Signal Voltage Gain Maximum Output Voltage Swing 0.1Hz to 10Hz 0.1Hz to 1Hz f = 10Hz (Note 4) VCM = V – to 2.7V VS = ±2.375V to ±8V RL = 100kΩ, VOUT = ±4.75V RL = 10kΩ l l l l Slew Rate Gain Bandwidth Product Supply Current RL = 100kΩ RL = 10kΩ, CL = 50pF l No Load 110 110 130 –4.6/3.2 ±4.9 3 1 2 130 130 160 –4.9/4.2 ±4.97 0.8 0.8 200 l Internal Sampling Frequency ±100 ±150 ±50 ±150 700 330 495 1049fb 2 LTC1049 Electrical Characteristics Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. 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 LTC1049. 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. Typical Performance Characteristics Common Mode Input Range vs Supply Voltage Voltage Noise vs Frequency 140 8 60 40 100 10 1k 10k 2 0 –2 60 40 –6 –20 200 0 1 4 5 2 3 6 SUPPLY VOLTAGE (±V) 7 8 –40 100 SHORT-CIRCUIT OUTPUT CURRENT (mA) SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) 300 200 100 6 7 8 9 10 11 12 13 14 15 TOTAL SUPPLY VOLTAGE (V) LTC1049 • TPC04 0 –50 –25 220 10M 1.2 400 5 1M Output Short-Circuit Current vs Supply Voltage 500 100 10k 100k FREQUENCY (Hz) LTC1049 • TPC03 Supply Current vs Temperature 400 160 1k LTC1049 • TPC02 Supply Current vs Supply Voltage 220 160 180 LTC1049 • TP01 280 140 GAIN 20 120 0 FREQUENCY (Hz) 340 100 PHASE –4 –8 100k 80 80 4 VOLTAGE GAIN (dB) COMMON MODE VOLTAGE (V) VOLTAGE NOISE (nV/√Hz) 80 60 VS = ±5V 100 NO LOAD PHASE SHIFT (DEGREES) 100 20 VCM = V – 6 120 Gain/Phase vs Frequency 120 50 25 0 75 TEMPERATURE (°C) 100 125 LTC1049 • TPC05 0.8 0.4 0 ≈ ≈ –3 –6 –9 4 8 10 12 14 6 TOTAL SUPPLY VOLTAGE, V+ TO V–(V) 16 LTC1049 • TPC06 1049fb 3 LTC1049 Typical Performance Characteristics Sampling Frequency vs Supply Voltage Sampling Frequency vs Temperature 5 3000 CMRR vs Frequency 160 VS = ±5V VS = ±5V 2500 2000 1500 4 120 3 CMRR (dB) SAMPLING FREQUENCY (kHz) SAMPLING FREQUENCY (Hz) 140 2 100 80 60 40 1 20 1000 4 0 50 25 0 75 100 –50 –25 AMBIENT TEMPERATURE (°C) 14 16 6 8 10 12 TOTAL SUPPLY VOLTAGE, V + TO V – (V) 125 0 1 10 100 1k FREQUENCY (Hz) 10k LTC1049 • TPC09 LTC1049 • TPC08 LTC1049 • TPC07 Small-Signal Transient Response Overload Recovery 100k Large-Signal Transient Response 400mV INPUT 100mV STEP 6V STEP OUTPUT 0.2V/DIV 1µs/DIV 5µs/DIV 0V 0V 2V/DIV –5V AV = –100 VS = ±5V 0.5ms/DIV LTC1049 • TPC10 AV = 1 RL = 10k CL = 50pF VS = ±5V LTC1049 • TPC11 AV = 1 RL = 10k CL = 50pF VS = ±5V LTC1049 • TPC12 LTC1049 DC to 1Hz Noise VS = ±5V 1Hz NOISE 1µV/DIV NOISE VOLTAGE 1µV/DIV 10s/DIV LTC1049 • TPC13 1049fb 4 LTC1049 Typical Performance Characteristics LTC1049 DC to 10Hz Noise VS = ±5V NOISE VOLTAGE 1µV/DIV 10Hz NOISE 1µV/DIV 1s/DIV LTC1049•TPC14 Test Circuits Electrical Characteristics Test Circuit DC to 10Hz and DC to 1Hz Noise Test Circuit 140 8 COMMON MODE VOLTAGE (V) VOLTAGE NOISE (nV/√Hz) 120 100 80 60 40 20 VCM = V – 6 4 2 0 –2 –4 –6 10 100 1k 10k 100k FREQUENCY (Hz) LTC1049 • TP01 –8 0 1 4 5 2 3 6 SUPPLY VOLTAGE (±V) 7 8 LTC1049 • TPC02 1049fb 5 LTC1049 Applications Information ACHIEVING PICOAMPERE/MICROVOLT PERFORMANCE Picoamperes In order to realize the picoampere level of accuracy of the LTC1049, 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™, Kel-F); cleaning of all insulating surfaces to remove fluxes and other residues will probably be necessary—particularly for high temperature perfor mance. 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 LTC1049’s ultralow 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. 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 — twice the maximum drift specification of the LTC1049. The copper/kovar junction, formed when wire or printed circuit traces contact a package lead, has a thermal EMF of approximately 35µV/°C—300 times the maximum drift specification of the LTC1049. 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. PACKAGE-INDUCED OFFSET VOLTAGE Package-induced thermal EMF effects are another important source of errors. It arises at the copper/kovar junctions formed when wire or printed circuit traces contact a package lead. Like all the previously mentioned thermal EMF effects, it is outside the LTC1049’s offset nulling loop and cannot be cancelled. The input offset voltage specification of the LTC1049 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. LOW SUPPLY OPERATION The minimum supply for proper operation of the LTC1049 is typically below 4.0V (±2.0V). In single supply applica tions, PSRR is guaranteed down to 4.7V (±2.35V) to ensure proper operation down to the minimum TTL specified voltage of 4.75V. PIN COMPATIBILITY The LTC1049 is pin compatible with the 8-pin versions of 7650, 7652 and other chopper-stabilized amplifiers. The 7650 and 7652 require the use of two external capacitors connected to Pins 1 and 8 which are not needed for the LTC1049. Pins 1, 5, and 8 of the LTC1049 are not connected internally; thus, the LTC1049 can be a direct plug- in for the 7650 and 7652, even if the two capacitors are left on the circuit board. 1049fb 6 LTC1049 Typical Applications Low Power, Low Hold Step Sample-and-Hold 5V 13 2 4.5 LTC201 VIN S/H 3 2 1 3 – 5V 7 LTC1049 + 0.47µF MYLAR 4 6 VOUT DROOP ≤1mV/s HOLD STEP ≤20µV IS = 250µA TYP LTC1049 • TA02 1049fb 7 LTC1049 Typical Applications Low Power, Single Supply, Low Offset Instrumentation Amp 5V 198k 2k 2 – – VIN + 198k 2 7 LTC1049 3 2k 6 – 7 LTC1049 3 4 + 6 VOUT 4 + VIN GAIN = 100 IS = 400µA CMRR ≥ 60dB, WITH 0.1% RESISTORS (RESISTORS LIMITED) LTC1049 • TA03 1049fb 8 LTC1049 Package Description J8 Package 8-Lead CERDIP (Narrow .300 Inch, Hermetic) (Reference LTC DWG # 05-08-1110) CORNER LEADS OPTION (4 PLCS) .023 – .045 (0.584 – 1.143) HALF LEAD OPTION .045 – .068 (1.143 – 1.650) FULL LEAD OPTION .005 (0.127) MIN .405 (10.287) MAX 8 7 6 5 .025 (0.635) RAD TYP .220 – .310 (5.588 – 7.874) 1 .300 BSC (7.62 BSC) 2 3 4 .200 (5.080) MAX .015 – .060 (0.381 – 1.524) .008 – .018 (0.203 – 0.457) 0° – 15° NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS .045 – .065 (1.143 – 1.651) .014 – .026 (0.360 – 0.660) .100 (2.54) BSC .125 3.175 MIN J8 0801 OBSOLETE PACKAGE 1049fb 9 LTC1049 Package Description N8 Package 8-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510) .400* (10.160) MAX 8 7 6 5 1 2 3 4 .255 ± .015* (6.477 ± 0.381) .300 – .325 (7.620 – 8.255) .008 – .015 (0.203 – 0.381) ( +.035 .325 –.015 8.255 +0.889 –0.381 ) .045 – .065 (1.143 – 1.651) .065 (1.651) TYP .100 (2.54) BSC .130 ± .005 (3.302 ± 0.127) .120 (3.048) .020 MIN (0.508) MIN .018 ± .003 (0.457 ± 0.076) N8 1002 NOTE: 1. DIMENSIONS ARE INCHES MILLIMETERS *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm) 1049fb 10 LTC1049 Package Description S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .050 BSC .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 8 .245 MIN .160 ±.005 5 .150 – .157 (3.810 – 3.988) NOTE 3 1 RECOMMENDED SOLDER PAD LAYOUT .010 – .020 × 45° (0.254 – 0.508) 2 3 4 .053 – .069 (1.346 – 1.752) .004 – .010 (0.101 – 0.254) 0°– 8° TYP .016 – .050 (0.406 – 1.270) NOTE: 1. DIMENSIONS IN 6 .228 – .244 (5.791 – 6.197) .030 ±.005 TYP .008 – .010 (0.203 – 0.254) 7 .014 – .019 (0.355 – 0.483) TYP INCHES (MILLIMETERS) 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) .050 (1.270) BSC SO8 0303 1049fb 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. 11 LTC1049 Typical Application Thermocouple-Based Temperature to Frequency Converter 6V V+ GND – – + 1M LTC1049 R– Q2 2N3906 + 6.81k* Q1 2N3904 NC 10k 100k K LT1025 6V 0.02µF TYPE K THERMOCOUPLE l1 l2 100k C1 100pF C3 0.47µF 1.5k 240k + 100°C TRIM C4 300pF 6V 9 11 14 C2 390pF † S1 10 S4 IS = 360µA SUPPLY RANGE = 4.5V to 10V S2 3 *IRC/TRW–MTR–5/+120ppm †POLYSTYRENE = 74C14 S3 2 OUTPUT 0 – 100°C = 0 – 1kHz LT1004 – 1.2 6.8µF 16 15 l3 6 7 LTC201 1 8 LTC1049 • TA04 1049fb 12 Linear Technology Corporation LT 0406 REV B • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 1991