LTC2997 Remote/Internal Temperature Sensor FEATURES DESCRIPTION n The LTC®2997 is a high-accuracy analog output temperature sensor. It converts the temperature of an external sensor or its own temperature to an analog voltage output. A built-in algorithm eliminates errors due to series resistance between the LTC2997 and the sensor diode. n n n n n n n n n Converts Remote Sensor or Internal Diode Temperature to Analog Voltage ±1°C Remote Temperature Accuracy ±1.5°C Internal Temperature Accuracy Built-In Series Resistance Cancellation 2.5V to 5.5V Supply Voltage 1.8V Reference Voltage Output 3.5ms VPTAT Update Time 4mV/°K Output Gain 170μA Quiescent Current Available in 6-Pin 2mm × 3mm DFN Package The LTC2997 gives accurate results with low-cost diodeconnected NPN or PNP transistors or with integrated temperature transistors on microprocessors or FPGAs. Tying pin D+ to VCC configures the LTC2997 to measure its internal temperature. The LTC2997 provides an additional 1.8V reference voltage output which can be used as an ADC reference input or for generating temperature threshold voltages to compare against the VPTAT output. APPLICATIONS n n n n n n Temperature Measurement Remote Temperature Measurement Environmental Monitoring System Thermal Control Desktop and Notebook Computers Network Servers The LTC2997 provides a precise and versatile micropower solution for accurate temperature sensing. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION Single Remote Temperature Sensor VPTAT vs Remote Sensor Temperature 2.5V TO 5.5V 1.8 0.1μF 1.6 D+ VCC VREF 1.8V LTC2997 470pF D– GND VPTAT 4mV/K 2997 TA01a VPTAT (V) MMBT 3904 1.4 1.2 1.0 0.8 25 50 75 100 125 150 –50 –25 0 REMOTE SENSOR TEMPERATURE (°C) 2997 TA01b 2997fa 1 LTC2997 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) Terminal Voltages VCC........................................................... –0.3V to 6V D+, D –, VPTAT, VREF ......................–0.3V to VCC + 0.3V Operating Ambient Temperature Range LTC2997C ................................................ 0°C to 70°C LTC2997I .............................................–40°C to 85°C LTC2997H .......................................... –40°C to 125°C Storage Temperature Range .................. –65°C to 150°C PIN CONFIGURATION TOP VIEW D+ 1 D– 2 6 VREF 7 5 GND 4 VCC VPTAT 3 DCB PACKAGE 6-LEAD (2mm w 3mm) PLASTIC DFN TJMAX = 150°C, θJA = 64°C/W EXPOSED PAD PCB GROUND CONNECTION OPTIONAL ORDER INFORMATION Lead Free Finish TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2997CDCB#TRMPBF LTC2997CDCB#TRPBF LFQZ 6-Lead (2mm × 3mm) Plastic DFN 0°C to 70°C LTC2997IDCB#TRMPBF LTC2997IDCB#TRPBF LFQZ 6-Lead (2mm × 3mm) Plastic DFN –40°C to 85°C LTC2997HDCB#TRMPBF LTC2997HDCB#TRPBF LFQZ 6-Lead (2mm × 3mm) Plastic DFN TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container. Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ –40°C to 125°C 2997fa 2 LTC2997 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VCC = 3.3V, unless otherwise noted. SYMBOL PARAMETER VCC Supply Voltage UVLO Supply Undervoltage Lockout Threshold ICC Average Supply Current CONDITIONS VCC Falling MIN TYP l MAX UNITS 2.5 3.3 5.5 V l 1.7 1.9 2.1 V l 120 170 250 μA 1.797 1.793 1.790 1.787 1.8 1.8 1.8 1.8 1.803 1.804 1.807 1.808 V V V V ±1.5 mV Temperature Monitoring VREF Reference Voltage LTC2997 LTC2997C LTC2997I LTC2997H l l l VREF Load Regulation Error ILOAD = ±200μA; VCC = 3.3V l (Note 3) l Remote Sense Current Diode Select Threshold –8 TUPDATE Temperature Update Interval KT VPTAT Slope η = 1.004 (Note 4) VPTAT Load Regulation ILOAD = ±200μA; VCC = 3.3V (Note 7) TINT Internal Temperature Error LTC2997C, LTC2997I LTC2997H TRMT Remote Temperature Error, η = 1.004 0°C to 100°C (Notes 5, 7) –40°C to 0°C (Notes 5, 7) 100°C to 125°C (Notes 5, 7) TVCC Temperature Error vs Supply 2.5V ≤ VCC ≤ 5.5V TRS Series Resistance Cancellation Error RSERIES = 100Ω Temperature Noise (Note 6) 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: All currents into pins are positive; all voltages are referenced to GND unless otherwise noted. –192 μA VCC – 600 VCC – 300 VCC – 100 mV 3.5 ms 5 4 mV/°K ±1.5 mV ±0.5 ±1.5 ±2 °C °C ±0.25 ±0.25 ±1 ±1.5 ±1.5 °C °C °C l ±0.1 ±1 °C/V l ±0.25 ±1 °C l l 0.25 0.015 °C RMS °C/√Hz Note 3: If voltage on pin D+ exceeds the diode select threshold the LTC2997 uses the internal diode sensor. Note 4: η = ideality factor of remote diode Note 5: Remote diode temperature. Note 6: Guaranteed by design and not subject to test. Note 7: Guaranteed by design and test correlation. 2997fa 3 LTC2997 TYPICAL PERFORMANCE CHARACTERISTICS Remote Temperature Error vs TA with Remote Diode at 25°C 3 2 2 2 1 1 1 0 –1 TINT ERROR (°C) 3 0 –1 –2 –2 –3 –50 –25 0 25 50 75 TA (°C) –3 –50 –25 100 125 150 –1 0 25 50 75 TA (°C) –3 –50 –25 100 125 150 0 25 50 75 TA (°C) 100 125 150 2997 G02 Temperature Error vs VCC - Remote/Internal, T VCC 2997 G03 Remote Temperature Error vs CDECOUPLE (Between D+ and D –) Remote Temperature Error vs Series Resistance, TRS 0.4 1.5 0.2 1.0 0.8 0.4 0 –0.2 –0.4 ERROR (°C) 0.5 ERROR (°C) ERROR (°C) 0 –2 2997 G01 0 0 –0.5 –0.6 –0.4 –1.0 –0.8 –1.0 1 2 4 3 6 5 –1.5 0 200 VCC (V) 400 600 800 SERIES RESISTOR (Ω) 2997 G04 2.4 0.25 2.2 1.810 VCC RISING VCC FALLING 1.805 1.8 1.800 1.6 1.4 0.05 5 VRFE (V) UVLO (V) 0.10 3 4 1 2 DECOUPLE CAPACITOR (nF) Buffered Reference Voltage vs Temperature, VREF 2.0 0.20 0.15 0 2997 G06 UVLO vs Temperature VCC Rising, Falling 0.30 0 0.01 –0.8 1000 2997 G05 VPTAT Noise vs Averaging Time VPTAT NOISE (°C RMS) Internal Temperature Error vs TA, TINT 3 TRMT ERROR (°C) TRMT ERROR (°C) Temperature Error with LTC2997 at Same Temperature as Remote Diode TA = 25°C, VCC = 3.3V unless otherwise noted. 1.795 1.2 10 1 0.1 AVERAGING TIME (ms) 100 2997 G07 1.0 –50 –25 0 25 50 75 100 125 150 175 TA (°C) 2997 G08 1.790 –50 –25 0 25 50 75 TA (°C) 100 125 150 2997 G09 2997fa 4 LTC2997 TYPICAL PERFORMANCE CHARACTERISTICS Load Regulation of VPTAT – Voltage vs Current 1.28 VCC = 2.5V VCC = 3.5V VCC = 4.5V VCC = 5.5V 1.810 Supply Current vs Temperature 200 VCC = 2.5V VCC = 3.5V VCC = 4.5V VCC = 5.5V 1.27 190 SUPPLY CURRENT (μA) Load Regulation of VREF – Voltage vs Current 1.820 TA = 25°C, VCC = 3.3V unless otherwise noted. VPTAT (V) VREF (V) 1.26 1.800 1.25 1.24 1.790 0 –2 2 LOAD CURRENT (mA) –4 4 1.22 –4 2 –2 0 LOAD CURRENT (mA) 2997 G10 4 TRMT ERROR (°C) VPTAT (°C) 10 ABSOLUTE TEMPERATURE ERROR (°C) 100 50 25 0 AIR 0 1 BOILING WATER 3 2 TIME (s) LTC2997 CONNECTED VIA 5 INCH 30AWG WRAPPING WIRES 4 2 0 –2 –4 5 –6 –200 –100 0 100 200 ILEAKAGE (nA) 2997 G13 25 50 75 TA (°C) 100 125 150 Single Wire Remote Temperature Error vs Potential Difference Between Remote and Local Ground (VAC) 6 75 0 2997 G12 Remote Temperature Error vs Leakage Current at D+ with Remote Diode at 25°C, T RMT 125 –50 150 –50 –25 4 2997 G11 LTC2997 Internal Sensor Thermal Step Response ICE –25 WATER 170 160 1.23 1.780 180 2997 G14 VAC = 50mVP-P 1 0.1 0.01 0.1 1 100 10 FREQUENCY (kHz) 1000 2997 G15 2997fa 5 LTC2997 PIN FUNCTIONS D+: Diode Sense Current Source. D+ sources the remote diode sensing current. Connect D+ to the anode of the remote sensor device. It is recommended to connect a 470pF bypass capacitor between D+ and D–. Larger capacitors may cause settling time errors (see Typical Performance Characteristics). If D+ is tied to VCC, the LTC2997 measures the internal sensor temperature. Tie D+ to VCC if unused. VPTAT : VPTAT Voltage Output. The voltage on this pin is proportional to the sensor’s absolute temperature. VPTAT can drive a capacitive load of up to 1000pF. For larger load capacitance, insert 1kΩ between VPTAT and load to guarantee stability. VPTAT can drive up to ±200μA of load current. VPTAT is pulled low when the supply voltage goes below the under voltage lockout threshold. D–: Diode Sense Current Sink. Connect D– to the cathode of the remote sensor device. Tie D– to GND for single wire remote sensing (see Typical Applications) or internal temperature sensing. VREF : Voltage Reference Output. VREF provides a 1.8V reference voltage. VREF can drive a capacitive load of up to 1000pF. For larger load capacitance, insert 1kΩ between VREF and load to guarantee stability. VREF can drive up to ±200μA of load current. Leave VREF open if unused. GND: Device Ground. VCC : Supply Voltage. Bypass this pin to GND with a 0.1μF (or greater) capacitor. VCC operating range is 2.5V to 5.5V. Exposed Pad: Exposed pad may be left open or soldered to GND for better thermal coupling. 2997fa 6 LTC2997 BLOCK DIAGRAM VSUPPLY 4 VCC + – UVLO TEMPERATURE TO VOLTAGE CONVERTER + – 1 2 3 1.2V EXT/INT MUX + D+ 1.8V VREF – 6 600k INTERNAL SENSOR EXTERNAL SENSOR VPTAT MUX 300mV D– 1200k GND 5 2997 BD 2997fa 7 LTC2997 OPERATION The Block Diagram shows the main components of the LTC2997. The LTC2997 measures temperature using either a remote or internal diode and provides a buffered voltage proportional to absolute temperature (VPTAT) and a buffered 1.8V reference voltage. Remote temperature measurements usually use a diode connected transistor as a temperature sensor, allowing the remote sensor to be a discrete NPN (ex. MMBT3904) or an embedded PNP device in a microprocessor or FPGA. Temperature measurements are conducted by measuring the diode voltage at multiple test currents. The diode equation can be solved for T, where T is degrees Kelvin, IS is a process dependent factor on the order of 10–13A, η is the diode ideality factor, k is the Boltzmann constant and q is the electron charge: T= V q • DIODE ⎛I ⎞ η•k ln ⎜ D ⎟ ⎝IS ⎠ This equation has a relationship between temperature and voltage, dependent on the process-dependent variable IS. Measuring the same diode (with the same value IS) at two different currents yields an expression which is independent I1, I2 of IS. The value in the natural logarithm term becomes the ratio of the two currents, which is process independent. T= – V DIODE1 V • DIODE2 ⎛I ⎞ η•k ln ⎜ D2 ⎟ ⎝ I D1 ⎠ q Series Resistance Cancellation Resistance in series with the remote diode causes a positive temperature error by increasing the measured voltage at each test current. The composite voltage equals: VDIODE + VERROR = η ⎛I ⎞ kT • ln ⎜ D ⎟ +R S • I D q ⎝IS ⎠ where RS is the series resistance. The LTC2997 removes this error term from the sensor signal by subtracting a cancellation voltage (see Figure 1). A resistance extraction circuit uses one additional current (I3) to determine the series resistance in the measurement path. Once the correct value of the resistor is determined VCANCEL equals VERROR. Now the temperature to voltage converter's input signal is free from errors due to series resistance and the sensor temperature can be determined using currents I1 and I2. I3 D+ RSERIES RESISTANCE EXTRACTION CIRCUIT VERROR VBE D– + – VCANCEL = VERROR VBE TEMPERATURE TO VOLT CONVERTER VPTAT 2997 F01 Figure 1. Series Resistance Cancellation 2997fa 8 LTC2997 APPLICATIONS INFORMATION Power Up and UVLO The basic LTC2997 application using an external NPN transistor is shown in Figure 2. 2.5V TO 5.5V Input Noise Filtering 0.1μF D+ MMBT3904 VCC VREF 1.8V LTC2997 470pF D– GND VPTAT 4mV/K 2997 F02 Figure 2. Basic Application Circuit The VCC pin must exceed the undervoltage threshold of 1.9V (typical) for normal operation. For VCC below UVLO the LTC2997 enters power-on reset and VPTAT is pulled low. Temperature Measurements Before each conversion a voltage comparator connected to D+ automatically sets the LTC2997 into external or internal mode. Tying D+ to VCC enables internal mode and VPTAT represents the die temperature. The VPTAT gain, KT, is 4mV/K. The temperature in Kelvin is easily calculated: TKELVIN = of up to 100Ω to an error smaller than 1°C (see Typical Performance Characteristics). The LTC2997 continuously measures the sensor diode at different test currents and updates VPTAT every 3.5ms (typical). VPTAT KT For VD+ more than 300mV below VCC (typical) the LTC2997 assumes that an external sensor is connected and will start sending sensing currents to the remote sensor diode. The anode of the external sensor must be connected to pin D+. The cathode should be connected to D– for best external noise immunity. For single wire measurements the sensor cathode is connected to remote GND and D– must be connected to local GND (see Figure 7). Small ground DC voltages (<±200mV) between the two cathode potentials do not impact the measurement accuracy. AC voltages at odd multiples of 6kHz (±20%) cause temperature measurement errors (see Typical Performance Characteristics). The LTC2997 is calibrated to yield a VPTAT gain of 4mV/K for a remote diode with an ideality factor of 1.004. A built-in algorithm cancels errors due to series resistance The change in sensor voltage per °C is hundreds of microvolts, so electrical noise must be kept to a minimum. Bypass D+ and D– with a 470pF capacitor close to the LTC2997 to suppress external noise. Bypass capacitors greater 1nF cause settling time errors of the different measurement currents. See Typical Performance Characteristics. Long wires connecting external sensors add series resistance, mutual capacitance between D+ and D–, and cause leakage currents. A 10m CAT6 cable has ~500pF of mutual capacitance and adds negligible series resistance and leakage currents. Recommended shielding and PCB trace considerations for best noise immunity are illustrated in Figure 3. GND SHIELD TRACE 470pF D+ D– LTC2997 GND NPN SENSOR 2997 F03 Figure 3. Recommended PCB Layout Output Noise Filtering The VPTAT output typically exhibits 1mV RMS (0.25°C RMS) noise. For applications which require lower noise digital or analog averaging can be applied to the output. Choose the averaging time according to the following equation: ⎛ 0.015 [°C / Hz ] ⎞ 2 t AVG = ⎜ ⎟ TNOISE ⎠ ⎝ where tAVG is the averaging time and TNOISE the desired temperature noise in °C RMS. For example, if the desired noise performance is 0.015°C RMS, set the averaging time to one second. See Typical Performance Characteristics. 2997fa 9 LTC2997 APPLICATIONS INFORMATION Choosing a Sensor 10Ω The LTC2997 is factory calibrated for an ideality factor of 1.004, which is typical of the popular MMBT3904 NPN transistor. Semiconductor purity and wafer-level processing intrinsically limit device-to-device variation, making these devices interchangeable between most manufacturers with a temperature error of typically less than 0.5°C. Some recommended sources are listed in Table 1: Table 1. Recommended Transistors for Use as Temperature Sensors. MANUFACTURER PART NUMBER PACKAGE Fairchild Semiconductor MMBT3904 SOT-23 Central Semiconductor CMPT3904 SOT-23 Diodes, Inc. MMBT3904 SOT-23 On Semiconductor MMBT3904LT1 SOT-23 NXP MMBT3904 SOT-23 Infineon MMBT3904 SOT-23 UMT3904 SC-70 Rohm Discrete two terminal diodes usually have ideality factors significantly higher than 1.004 and are therefor not recommended as remote sensing devices. Protection The LTC2997 can withstand up to ±4kV of electrostatic discharge (ESD, human body). ESD beyond this voltage can damage or degrade the device including lowering the remote sensor measurement accuracy due to increased leakage currents on D+ and D–. To protect the sensing inputs against larger ESD strikes, external protection can be added using TVS diodes to ground (Figure 4). Care must be taken to choose diodes with low capacitance and low leakage currents in order not to degrade the external sensor measurement accuracy (see Typical Performance Characteristics). MMBT3904 D+ LTC2997 220pF 10Ω D– GND PESD5Z6.0 2997 F04 Figure 4. Increasing ESD Robustness with TVS Diodes Ideality Factor Scaling While an ideality factor value of 1.004 is typical of many sensor devices, small deviations can yield significant temperature errors. The ideality factor acts as a temperature scaling factor. The temperature error for a 1% deviation is 1% of the Kelvin temperature. Thus, at 25°C (298K) a +1% accurate ideality factor error yields a +2.98 degree error. At 85°C (358K) a +1% error yields a 3.58 degree error. It is possible to scale the PTAT voltage if an external sensor with an ideality factor other than 1.004 is used. The scaling equation for the compensated PTAT voltage is listed below. LTC2997 Ideality Calibration Value: ηCAL = 1.004 Actual Remote Sensor Ideality Value: ηACT Compensated PTAT Voltage: VPTAT _ COMP = η CAL • VPTAT _ MEAS η ACT Compensated Kelvin Temperature: TKELVIN _ COMP = η CAL • TKELVIN _ MEAS η ACT Compensated Celsius Temperature: TCELSIUS _ COMP = η CAL •(TKELVIN _ MEAS ) – 273.15 η ACT 2997fa 10 LTC2997 TYPICAL APPLICATIONS 2.5V TO 5.5V 0.1μF MMBT3904 VCC D+ VREF 1.8V LTC2997 470pF D– GND VPTAT 4mV/K 2997 F05 Figure 5. Single Remote Temperature Sensor 2.5V TO 5.5V 0.1μF D+ VCC VREF μC 1.8V LTC2997 D– GND VPTAT 4mV/K A/D 2997 F06 Figure 6. Internal Temperature Sensor 2.5V TO 5.5V 0.1μF D+ CPU/ FPGA/ ASIC VCC VREF 1.8V LTC2997 470pF D– GND VPTAT 4mV/K 2997 F07 Figure 7. Remote CPU Temperature Sensor 2997fa 11 LTC2997 TYPICAL APPLICATIONS 2.5V TO 5.5V 0.1μF D+ 2N3904 VCC 1.8V VREF LTC2997 470pF D– GND 4mV/K VPTAT 2997 F08 Figure 8. Single Wire Remote Temperature Sensor 0.30 2.5V TO 5.5V D+ VCC >1k VPTAT LTC2997 VPTAT(FILTER) CFILTER D– GND 2997 F09 VPTAT NOISE (°C RMS) 0.25 0.1μF 0.20 0.15 0.10 0.05 0 0.005 5 0.5 0.05 RC TIME CONSTANT (ms) 50 Figure 9. Output Noise Filter 2.5V TO 5.5V CAT6 STP CABLE 10m MAXIMUM 0.1μF D+ MMBT 3904 VCC VREF 1.8V LTC2997 470pF D– GND VPTAT 4mV/K 2997 F10 Figure 10. Long Distance Remote Temperature Sensor 2997fa 12 LTC2997 TYPICAL APPLICATIONS MEASURE TEMPERATURE AND SET TARGET TEMPERATURE WITH RESISTIVE DIVIDER INTEGRATE TEMPERATURE ERROR PWM OSCILLATOR 5V 100μF 10M 0.1μF 100pF 10M 200k ZXM64PO35 D + VCC 1k – VPTAT 100k LTC2997 470pF 5V LTC6079 – + D– GND VREF + LTC6079 CET 3904 22k VTARGET 75k VREF 100k 1M 10Ω RHEATER 2997 F11 Figure 11. Analog PWM Heater Controller CET 3904 5V 10Ω RHEATER 0.1μF D+ VCC VPTAT – 4mV/K LTC2997 470pF D– GND VREF + 1.8V LTC6079 IRF3708 22k VTARGET = 1.3917V 75k 2997 F12 Figure 12. 75°C Analog Heater Controller 2997fa 13 LTC2997 TYPICAL APPLICATIONS 2.5V TO 5.5V 0.1μF VCC D+ VREF LTC2997 470pF MMBT3904 1.8V D– GND VPTAT 4mV/K 2997 F13 Figure 13. Remote Diode Sensor Insensitive to Cable Connection Polarity 12V 5V 0.1μF 39k B6015L12F 68k FAN MMBT 3904 D+ VCC 10k VREF – LTC2997 470pF VPTAT D– GND VCC + IRF3708 OUT MOD LTC6078 LTC6692 DIV SET 390k GND 2997 F14 Figure 14. Temperature Proportional PWM Fan Speed Controller 2997fa 14 LTC2997 TYPICAL APPLICATIONS 0.1μF 150k 2.5V TO 5.5V 1.8k 0.1μF 5V D+ VCC VREF 1.8V LTC2997 D– VPTAT 4mV/K 100k 1k – 62k GND 143k 7 LTC1150 1 + 4 10mV/°C 0V AT 0°C 1μF –5V 2997 F15 Figure 15. Celsius Thermometer 0.1μF 255k 2.5V TO 5.5V 0.1μF D+ VREF 1.8V LTC2997 D– 5V 270k VCC VPTAT 4mV/K 100k – 7 LTC1150 1 + 4 62k 10mV/°F 0V AT 0°F 1μF GND 2997 F16 –5V Figure 16. Fahrenheit Thermometer 2997fa 15 LTC2997 PACKAGE DESCRIPTION Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. DCB Package 6-Lead Plastic DFN (2mm × 3mm) (Reference LTC DWG # 05-08-1715 Rev A) 0.70 ±0.05 3.55 ±0.05 1.65 ±0.05 (2 SIDES) 2.15 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 1.35 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115 TYP 2.00 ±0.10 (2 SIDES) R = 0.05 TYP 3.00 ±0.10 (2 SIDES) 0.40 ± 0.10 4 6 1.65 ± 0.10 (2 SIDES) PIN 1 NOTCH R0.20 OR 0.25 × 45° CHAMFER PIN 1 BAR TOP MARK (SEE NOTE 6) 3 0.200 REF 0.75 ±0.05 1 (DCB6) DFN 0405 0.25 ± 0.05 0.50 BSC 1.35 ±0.10 (2 SIDES) 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (TBD) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 2997fa 16 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. LTC2997 REVISION HISTORY REV DATE DESCRIPTION A 9/11 Changed 4mV/°C to 4mV/°K in Features 1 Updated Description 1 Updated Electrical Characteristics 3 Added Graph G15 5 Updated Pin Functions PAGE NUMBER 6 Updated Applications Information 9, 10 Updated Figures 9, 10, 13, 15, 16 12, 14, 15 Updated Related Parts 18 2997fa 17 LTC2997 TYPICAL APPLICATION 5V + OUT = 4mV/K LTC6078 TYPE K THERMOCOUPLE – 1.3k 5V 127k 10k 5.6pF 0.1μF D+ VCC VPTAT LTC2997 D– GND VREF 2997 F17 Figure 17. Thermocouple Thermometer with Cold Junction Compensation RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC2990 Remote/Internal Temperature, Voltage and Current Monitor Measures Two Remote Diode Temperatures, ±1°C Accuracy, 0.06°C Resolution, ±2°C Internal Temperature Sensor, I2C Interface, LTC2909 Precision Triple/Dual Input UV, OV and Negative Voltage Monitor Two Adjustable Inputs, ±1.5% Accuracy, 6.5V Shunt Regulator LTC2919 Precision Triple/Dual Input UV, OV and Negative Voltage Monitor Two Adjustable Inputs, ±1.5% Accuracy, 6.5V Shunt Regulator, Open-Drain/RST, OUT1 and OUT2 Outputs LTC6078 LTC6078 Micropower Precision, Dual/Quad CMOS Rail-to-Rail Input/Output Amplifiers Maximum Offset Voltage of 25μV (25°C), Maximum Offset Drift of 0.7μV/°C, Maximum Input Bias of 1pA (25°C) to 50pA (≤85°C) LTC6079 Micropower Precision, Dual/Quad CMOS Rail-to-Rail Input/Output Amplifiers Maximum Offset Voltage of 25μV (25°C), Maximum Offset Drift of 0.7μV/°C, Maximum Input Bias of 1pA (25°C) to 50pA (≤85°C) 2997fa 18 Linear Technology Corporation LT 0911 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2011