LTK001 Thermocouple Cold Junction Compensator and Matched Amplifier thermocouple applications. It has low supply current to minimize warmup drift, very low offset voltage (<35µV), high gain, and extremely low input bias currents (<600pA) to allow high impedance input filters to be used without degrading offset voltage or drift. FEATURES ■ ■ ■ ■ ■ ■ 0.75°C Initial Accuracy (A Version) Extremely Low Warmup Drift Preset Outputs for Type E, J, K, R, S, T Single 5V to ± 20V Operation 480µA Typical Supply Current Available in 8-Pin DIP Package Matching of the kits is accomplished by separating the compensators and amplifiers according to the polarity of their initial (room temperature) errors. This eliminates the need to sum the errors of the two components to find the worst-case error. U APPLICATIO S ■ The LTK001 has direct thermocouple outputs of 60.9µV/°C (E), 51.7µV/°C (J), 40.6µV/°C (K, T), and 5.95µV/°C (R, S). It also has a 10mV/°C output which can be scaled to match any arbitrary thermocouple. Thermocouple Cold Junction Compensation U DESCRIPTIO The LTK001 is a thermocouple amplifier supplied with a matched cold junction compensator. By separating the amplifier and compensator functions, the problem of compensator temperature rise is virtually eliminated. The compensator is a selected version of the LT®1025 cold junction compensator. The amplifier, which is also available separately as LTKA0x has been specially selected for For multiple thermocouple applications using one compensator, amplifiers may be ordered separately (LTKA0x), still matched to the compensator. , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. For typical performance curves and applications circuits consult the LT1025 data sheet. U TYPICAL APPLICATIO Type K 10mV/°C Thermometer R2 100Ω FULL-SCALE TRIM R3** 255k 1% C2 0.1µF R1 1k 1% V+ V+ – LTKA0x VIN K – LT1025 GND * + C1 0.1µF + VOUT 10mV/°C V– TYPE K V0 R– R4* V– – *R4 ≤ V , R4 IS NOT REQUIRED (OPEN) FOR 30µA LT1025 TEMPERATURES ≥ 0°C. **SELECTED FOR 0°C–100°C RANGE LTK001 TA01 001fa 1 LTK001 W W W AXI U U ABSOLUTE RATI GS (Note 1) Amplifier (LTKA0x) Supply Voltage (Total V + to V –) ............................... 40V Differential Input Current (Note 2) ...................... ±10mA Common Mode Input Voltage ............. Equal to Supplies Output Short-Circuit Duration .......................... Indefinite Compensator (LT1025) Supply Voltage (VIN to Ground Pin) ......................... 36V Output Voltage (Forced) ............................................ 5V Output Short-Circuit Duration .......................... Indefinite Both Devices Operating Temperature Range LTK001AMJ8, LTK001MJ8 (OBSOLETE) ......................................................... – 55°C to 125°C LTK001ACN8, LTK001CN8 ...................... 0°C to 70°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature Range (Soldering, 10 sec.)...... 300°C U U W PACKAGE/ORDER I FOR ATIO TOP VIEW E 60.9µV/°C 1 VIN 2 VO 10mV/°C 3 8 7 6 GND 4 TOP VIEW VOS TRIM TOP VIEW 5 J 51.7µV/°C K,T 40.6µV/°C R,S 6µV/°C R– COMMON N8 PACKAGE 8-LEAD PDIP COMPENSATOR (LT1025) TJMAX = 100°C, θJA = 130°C/W (N8) VOS TRIM 1 8 VOS TRIM –IN 2 7 V+ +IN 3 V– 4 6 OUT 5 OVER COMP N8 PACKAGE 8-LEAD PDIP AMPLIFIER (LTKA0x) TJMAX = 100°C, θJA = 130°C/W 8 VOS TRIM 1 –IN 2 – + 7 V+ 6 OUT 5 OVER COMP +IN 3 4 V– H PACKAGE 8-LEAD TO-5 METAL CAN AMPLIFIER (LTKA0x) TJMAX = 150°C, θJA = 150°C/W, θJC = 45°C/W ORDER PART NUMBER ORDER PART NUMBER ORDER PART NUMBER KIT LTK001CN8 LTK001ACN8 AMPLIFIER ONLY (Note A) LTKA00CN8 LTKA01CN8 AMPLIFIER ONLY (Note A) LTKA00MH LTKA01MH J8 PACKAGE 8-LEAD CERDIP COMPENSATOR (LT1025) TJMAX = 150°C, θJA = 100°C/W (J8) LTK001MJ8 LTK001AMJ8 OBSOLETE PACKAGE OBSOLETE PACKAGE Consider the N8 Package for Alternate Source Note A: The polarity of the amplifier is indicated by the 0 or 1 in the part number. An LT1025 with a 0 identifier is properly matched with an LTKA00, while an LT1025 with a 1 identifier should be used with an LTKA01. Consult factory for parts specified with wider operating temperature ranges. 001fa 2 LTK001 ELECTRICAL CHARACTERISTICS (Matched Amplifier and Compensator) TA = 25°C, VS = ±15V (Amplifier), VS = 5V (Compensator) PARAMETER CONDITIONS Total Temperature Error at 25°C (Note 3) MIN Total Temperature Error at Temperature Extremes (Note 9) 0°C ≤ TJ ≤ 70°C 0°C ≤ TJ ≤ 70°C LTK001 TYP MAX UNITS 0.75 2.5 °C 0.75 2.5 °C Type K, T 0.86 2.5 °C 5.0 5.0 °C Type E (Note 12) 0.05 0.09 °C/°C Type J 0.06 0.09 °C/°C Type K, T 0.07 0.10 °C/°C Type R, S 0.28 0.32 °C/°C Type E 2.0 5 Type J 2.1 5 °C Type K, T 2.6 5.2 °C (Note 12) °C 16 16 °C Type E 6 8.5 °C Type J 6 8.5 °C 6.3 9 °C 30 30 °C 0.1 0.1 °C/V 900 µA Type K, T Type R, S (Note 12) Temperature Error Change with Supply Voltage (Note 5) Supply Current MIN Type J Type R, S – 55°C ≤ TJ ≤ 125°C MAX Type E Type R, S Slope Error (Notes 4 and 9) LTK001A TYP 480 900 480 001fa 3 LTK001 ELECTRICAL CHARACTERISTICS (Compensator LT1025) The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 5V unless otherwise noted. PARAMETER CONDITIONS Temperature Error at 10mV/°C Output (Note 9) TJ = 25°C, LTK001A TJ = 25°C, LTK001 Full Temperature Span Temperature Error at Individual Outputs (Note 10) 0.3 0.5 ● 0.5 2.0 UNITS °C °C See Curve on LT1025 Data Sheet LTK001A: E, J, K, T LTK001A: R, S 0.4 0.4 0.75 1.5 °C °C LTK001: E, J, K, T LTK001: R, S 0.8 1.2 2.4 3.5 °C °C Full Temperature Span Supply Current COMPENSATOR (LT1025) MIN TYP MAX ● 4V ≤ VIN ≤ 36V 80 0°C ≤ TJ ≤ 70°C ● – 55°C ≤ TJ ≤ 125°C ● Change in Supply Current 4V ≤ VIN ≤ 36V Line Regulation (Note 11) 4V ≤ VIN ≤ 36V 10mV/°C Output Load Regulation (Note 11) 0 ≤ IO ≤ 1mA 10mV/°C Output Divider Impedance E J K, T R, S See Curve on LT1025 Data Sheet 100 µA 150 µA 200 µA 0.01 0.05 µA/V ● 0.003 0.02 °C/V ● 0.04 0.2 °C 2.5 2.1 4.4 3.8 kΩ kΩ kΩ kΩ 001fa 4 LTK001 ELECTRICAL CHARACTERISTICS (Amplifier LTKA0x) The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = ±15V, VCM = 0V, TJ = 25°C unless otherwise noted. PARAMETER AMPLIFIER (LTKA0x) MIN TYP MAX CONDITIONS Input Offset Voltage UNITS 10 35 µV Input 0ffset Voltage Drift with Temperature (Note 6) ● 0.3 1.5 µV/°C Input Bias Current 0°C ≤ TA ≤ 70°C – 55°C ≤ TA ≤ 125°C ● ● ± 200 ± 300 ± 600 ± 1500 Input Bias Current Drift with Temperature (Note 6) 1 5 lnput 0ffset Current 0°C ≤ TA ≤ 70°C – 55°C ≤ TA ≤ 125°C ● ● ± 100 ± 200 ± 500 ± 700 lnput Offset Current Drift with Temperature (Note 6) ● 0.6 4 Large Signal Voltage Gain RL = 10kΩ ● 400 2000 V/mV Common Mode Rejection Ratio VCM = ± 13.5V ● 106 130 dB Power Supply Rejection Ratio ± 2.5V ≤ VS ≤ ± 20V (Note 5) ● 106 125 dB Common Mode Input Voltage Range Notes 6, 7 Above V– 0.75 Referred to Supplies Supply Voltage Range Total V + to V – Voltage Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The inputs of the LTKA0x amplifier are clamped with diodes, so a differential voltage rating does not apply. Note 3: Total temperature error is the overall error at 25°C taking into account the offset of the amplifier, the offset at the compensator 10mV/°C output, and the error in the compensator divider network. Warmup drift is not included. Note 4: Slope error is the increase in total temperature error as ambient temperature is increased. It is guaranteed by design and by other tests, but is not tested directly. Note 5: This is a worst-case limit assuming that any or all supply voltages change. Note 6: Guaranteed, but not tested. Note 7: By referring common mode range to the supplies, the range referred to ground can be quickly calculated for any given supply voltage. With a single 5V supply, for instance, which has a worst-case low value of 4.7V, the upper common mode limit is 4.7V – 1V = 3.7V. The lower common mode limit is 0V + 0.75V = 0.75V. With ±15V supplies, the limits would be 14V and –14.25V, respectively. Common mode range has a temperature sensitivity of ≈ 2mV/°C. Note 8: Absolute output voltage swing is calculated by subtracting the given limits from actual supply voltage. These limits indicate the point where offset voltage has changed suddenly by 5µV. pA pA pA/°C 1.0 V IOUT = 0.1mA 0.8 V IOUT = 1mA 1.1 V ● Supply Current pA/°C V Below V + Output Voltage Swing (Notes 6, 8) pA pA ● 400 4.5 800 µA 40 V Note 9: Temperature error is defined as the deviation from the following formula: VOUT = α(T) + αß(T – 25°C)2 α = Typical thermocouple Seebeck coefficient as follows, E = 60.9µV/°C, J = 51.7µV/°C, K, T = 40.6µV/°C, R, S = 5.95µV/°C. α = 10mV/°C at the 10mV output. ß = Nonlinearity coefficient built into the LT1025 to help compensate for the nonlinearities of thermocouples. ß = 5.5 x 10 –4, generating 0.34°C bow for 25°C temperature change, and 1.36°C bow for 50°C change. Note 10: Temperature error at the individual outputs is the sum of the 10mV/°C output error plus the resistor divider error. Note 11: Line and load regulation do not take into account the effects of self-heating. Output changes due to self-heating can be calculated as follows: ∆VOUT (Line) = ∆VIN(Iq + Iload)(150°C/W) ∆VOUT (Load) = (∆Iload)(VIN)(150°C/W) = LT1025 supply current Load regulation is 30µA ≤ IO ≤ 1mA for TA ≤ 0°C. Note 12: Larger errors with type R and S thermocouples are due mostly to 35µV offset of the amplifier. This error can be reduced to 5µV max with the LTC®1050 or LTC1052 operational amplifiers. 001fa 5 LTK001 U PACKAGE DESCRIPTIO H Package 8-Lead TO-5 Metal Can (.200 Inch PCD) (Reference LTC DWG # 05-08-1320) .335 – .370 (8.509 – 9.398) DIA .305 – .335 (7.747 – 8.509) .040 (1.016) MAX .050 (1.270) MAX SEATING PLANE .165 – .185 (4.191 – 4.699) GAUGE PLANE .010 – .045* (0.254 – 1.143) REFERENCE PLANE .500 – .750 (12.700 – 19.050) .016 – .021** (0.406 – 0.533) .027 – .045 (0.686 – 1.143) 45° PIN 1 .028 – .034 (0.711 – 0.864) .200 (5.080) TYP .110 – .160 (2.794 – 4.064) INSULATING STANDOFF *LEAD DIAMETER IS UNCONTROLLED BETWEEN THE REFERENCE PLANE AND THE SEATING PLANE .016 – .024 **FOR SOLDER DIP LEAD FINISH, LEAD DIAMETER IS (0.406 – 0.610) H8(TO-5) 0.200 PCD 0204 OBSOLETE PACKAGE 001fa 6 LTK001 U PACKAGE DESCRIPTIO 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 001fa 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. 7 LTK001 U PACKAGE DESCRIPTIO 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) .130 ± .005 (3.302 ± 0.127) .065 (1.651) TYP .100 (2.54) BSC .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) RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1012 Picoamp Input Current Amplifier VOS = 120µV MAX, IOS = 280pA MAX LT1025 Thermocouple Cold Junction Comparator Micropower, 0.5°C Initial Accuracy LTC1050 Zero Drift Amplifier VOS = 5µV MAX, AVOL = 1V/µV MAX LTC2050 SOT-23 Zero Drift Amplifier VOS = 3µV MAX 001fa 8 Linear Technology Corporation LT/LT 0305 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com © LINEAR TECHNOLOGY CORPORATION 2001