LTC2996 Temperature Sensor with Alert Outputs Features Description Converts Remote or Internal Diode Temperature to Analog Voltage n Adjustable Overtemperature and Undertemperature Thresholds n Voltage Output Proportional to Temperature n ±1°C Remote Temperature Accuracy n ±2°C Internal Temperature Accuracy n Built-In Series Resistance Cancellation n Open Drain Alert Outputs n 2.25V to 5.5V Supply Voltage n 1.8V Reference Voltage Output n 200μA Quiescent Current n 10-Lead 3mm × 3mm DFN Package The LTC®2996 is a high accuracy temperature sensor with adjustable overtemperature and undertemperature thresholds and open drain alert outputs. It converts the temperature of an external diode sensor or its own die temperature to an analog output voltage while rejecting errors due to noise and series resistance. The measured temperature is compared against upper and lower limits set with resistive dividers. If a threshold is exceeded, the device communicates an alert by pulling low the correspondent open drain logic output. n Applications n n n n n The LTC2996 gives ±1°C accurate temperature results using commonly available NPN or PNP transistors or temperature diodes built into modern digital devices. A 1.8V reference output simplifies threshold programming and can be used as an ADC reference input. The LTC2996 provides an accurate, low power solution for temperature monitoring in a compact 3mm × 3mm DFN package. Temperature Monitoring and Measurement System Thermal Control Network Servers Desktop and Notebook Computers Environmental Monitoring 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 Remote Temperature Monitor with Overtemperature and Undertemperature Thresholds VPTAT vs Remote Diode Temperature 2.25V TO 5.5V 1.8 1.8V VREF 43k VCC OT LTC2996 VTH UT VTL VPTAT OT T > 70°C UT T < –20°C 36k 102k 4mV/K D+ 470pF GND D– 2996 TA01a 1.6 TEMPERATURE CONTROL SYSTEM VPTAT (V) 0.1µF MMBT3904 1.4 1.2 1.0 0.8 25 50 75 100 125 150 –50 –25 0 REMOTE DIODE TEMPERATURE (°C) 2996 TA01b 2996f 1 LTC2996 Absolute Maximum Ratings Pin Configuration (Notes 1, 2) VCC ............................................................... –0.3V to 6V D+, D–, VPTAT, VREF.............................. –0.3V to VCC + 0.3V OT, UT, VTH, VTL.......................................... –0.3V to 6V Operating Ambient Temperature Range LTC2996C................................................. 0°C to 70°C LTC2996I..............................................–40°C to 85°C LTC2996H........................................... –40°C to 125°C Storage Temperature Range................... –65°C to 150°C TOP VIEW 10 OT VTH 1 VTL 2 D+ 3 D– 4 7 GND VPTAT 5 6 VCC 9 UT 11 8 VREF DD PACKAGE 10-LEAD (3mm × 3mm) PLASTIC DFN TJMAX = 150°C, θJA = 43°C/W EXPOSED PAD PCB GROUND CONNECTION OPTIONAL Order Information LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2996CDD#PBF LTC2996CDD#TRPBF LFQX 10-Lead (3mm × 3mm) Plastic QFN 0°C to 70°C 10-Lead (3mm × 3mm) Plastic QFN –40°C to 85°C LTC2996IDD#PBF LTC2996IDD#TRPBF LFQX LTC2996HDD#PBF LTC2996HDD#TRPBF LFQX –40°C to 125°C 10-Lead (3mm × 3mm) Plastic QFN Consult LTC Marketing for parts specified with wider operating temperature ranges. *Temperature grades are identified by a label on the shipping container. 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/ 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 l 2.25 l 1.7 l TYP MAX UNITS 5.5 V 1.9 2.1 V 200 300 µA 1.8 1.8 1.8 1.803 1.805 1.808 V V V ±1.5 mV VCC – 100 mV –192 µA Temperature Measurement VREF Reference Voltage LTC2996 LTC2996C LTC2996I, LTC2996H l l VREF Load Regulation ILOAD = ±200μA, VCC = 3.3V l Diode Select Threshold (Note 3) l Remote Diode Sense Current 1.797 1.795 1.790 VCC – 600 –8 VCC – 300 2996f 2 LTC2996 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 TCONV Temperature Update Interval KT VPTAT Slope Ideality Factor η = 1.004 VPTAT Load Regulation ILOAD = ±200μA TINT TRMT Internal Temperature Accuracy Remote Temperature Error, η = 1.004 CONDITIONS MIN LTC2996C, LTC2996I LTC2996H Temperature Error vs Supply TRS Series Resistance Cancellation Error MAX 3.5 5 l l 0°C to 85°C (Notes 4, 5) –40°C to 0°C (Notes 4, 5) 85°C to 125°C (Notes 4, 5) ms mV/K ±1.5 mV ±0.5 ±0.5 ±0.5 ±1 ±2 ±3 °C °C °C ±0.25 ±0.25 ±0.25 ±1 ±1.5 ±1.5 °C °C °C 0.15 0.01 °CRMS °CRMS/√Hz ±0.5 l RSERIES = 100Ω UNITS 4 Temperature Noise TVCC TYP l °C/V ±0.25 ±1 °C Temperature Monitoring TOFF VTH, VTL Offset l –3 –1 1 °C ∆THYST OT, UT Temperature Hysteresis l 2 5 10 °C IIN VTH, VTL, Input Current l ±20 nA Digital Outputs VOH High Level Output Voltage, OT, UT I = –0.5μA l VOL Low Level Output Voltage, OT, UT I = 3mA l 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. VCC – 1.2 V 0.4 V Note 3: If voltage on pin D+ exceeds the diode select threshold the LTC2996 uses the internal diode sensor. Note 4: Remote diode temperature, not LTC2996 temperature. Note 5: Guaranteed by design and test correlation. 2996f 3 LTC2996 Typical Performance Characteristics Remote Temperature Error vs Ambient Temperature Temperature Error with LTC2996 at Same Temperature as Remote Diode 3 TINTERNAL = TREMOTE Internal Temperature Error vs Ambient Temperature 3 TREMOTE = 35°C 2 2 1 1 1 0 –1 TINT ERROR (°C) 2 TRMT ERROR (°C) TRMT ERROR (°C) 3 TA = 25°C, VCC = 3.3V unless otherwise noted. 0 –1 –2 –2 –3 –50 –25 0 25 50 TA (°C) 75 100 –1 –2 –3 –50 125 0 –25 0 25 50 TA (°C) 75 100 –3 –50 125 –25 0 25 50 TA (°C) 75 2996 G02 2996 G01 Temperature Error vs Supply Voltage 0.3 125 2996 G03 Remote Temperature Error vs CDECOUPLE (Between D+ and D–) Remote Temperature Error vs Series Resistance 0.4 100 6 6 4 4 2 2 0.0 –0.1 ERROR (°C) 0.1 ERROR (°C) ERROR (°C) 0.2 0 0 –2 –2 –4 –4 –0.2 –0.3 –0.4 1 2 3 4 –6 6 5 0 200 VCC (V) 400 600 800 1000 SERIES RESISTANCE (Ω) 2996 G04 0.15 2.1 Buffered Reference Voltage vs Temperature 1.810 VCC RISING VCC FALLING 1.805 1.800 2.0 1.795 1.9 0.1 10 100 1 AVERAGING TIME (ms) 1000 2996 G07 1.8 –50 –25 10 VREF (V) 2.2 UVLO (V) VPTAT NOISE (°C RMS) 0.20 0.05 6 8 2 4 DECOUPLE CAPACITOR (nF) 2996 G06 UVLO vs Temperature VCC Rising, Falling 0.10 0 2996 G05 VPTAT Noise vs Averaging Time 0 0.01 –6 1200 0 25 50 75 TA (°C) 100 125 150 2996 G08 1.790 –60 –40 –20 0 20 40 60 80 100 140 160 TA (°C) 2996 G09 2996f 4 LTC2996 Typical Performance Characteristics Load Regulation of VREF Voltage vs Current 1.22 VCC = 2.5V VCC = 3.5V VCC = 4.5V VCC = 5.5V 1.810 Single Wire Remote Temperature Error vs Ground Noise Load Regulation of VPTAT Voltage vs Current 10 VCC = 2.5V VCC = 3.5V VCC = 4.5V VCC = 5.5V 1.21 VPTAT (V) VREF (V) 1.20 1.800 1.19 1.18 1.790 1.17 1.780 –4 0 –2 2 LOAD CURRENT (mA) 4 1.16 –4 2 –2 0 LOAD CURRENT (mA) 2996 G10 UT, OT, vs Output Sink Current 0.1 0.01 0.1 1 100 10 FREQUENCY (kHz) 1000 2996 G12 Remote Temperature Error vs Leakage Current at D+ with Remote Diode at 25°C, TRMT Supply Current vs Temperature 6 220 4 0.6 0.4 0.2 210 TRMT ERROR (°C) SUPPLY CURRENT (µA) 0.8 VUV/OV/TO1/TO2 (V) 4 1 2996 G11 1 0 VAC = 50mVP-P ABSOLUTE TEMPERATURE ERROR (°C) 1.820 TA = 25°C, VCC = 3.3V unless otherwise noted. 200 2 0 –2 190 –4 0 10 20 I (mA) 30 40 2996 G14 180 –50 –25 0 25 50 75 TA (°C) 100 125 150 –6 –200 –100 0 ILEAKAGE (nA) 100 200 2996 G17 2996 G16 2996f 5 LTC2996 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 LTC2996 measures the internal sensor temperature. Tie D+ to VCC if unused. OT: Overtemperature Logic Output. Open drain logic output that pulls to GND when VPTAT is above the threshold voltage on pin VTH. When VPTAT falls below the threshold voltage on pin VTH, an additional hysteresis of 20mV is required to release OT high. OT has a weak 400kΩ pull-up to VCC and may be pulled above VCC using an external pull-up. Leave OT open if unused. D –: Diode Sense Current Sink. Connect D – to the cathode of the remote sensor device. Tie D – to GND for single wire remote temperature measurement (see Applications Information) or internal temperature sensing. VPTAT: Proportional to Absolute Temperature Voltage Output. The voltage on this pin is proportional to the sensor’s absolute temperature. VPTAT can drive up to ±200μA of load current and up to 1000pF of capacitive load. For larger load capacitances insert 1kΩ between VPTAT and the load to ensure stability. VPTAT is pulled low when the supply voltage goes below the under voltage lockout threshold. Exposed Pad: Exposed pad may be left open or soldered to GND for better thermal coupling. GND: Device Ground UT: Undertemperature Logic Output. Open drain logic output that pulls to GND when VPTAT is below the threshold voltage on pin VTL. When VPTAT rises above the threshold voltage on pin VTL, an additional hysteresis of 20mV is required to release UT high. UT has a weak 400kΩ pullup to VCC and may be pulled above VCC using an external pull-up. Leave UT open if unused. VREF: Voltage Reference Output. VREF provides a 1.8V reference voltage. VREF can drive up to ±200μA of load current and up to 1000pF of capacitive load. For larger load capacitances, insert 1kΩ between VREF and the load to ensure stability. Leave VREF open if unused. VTL: Temperature Threshold Low. When VPTAT is below the voltage on VTL, UT is pulled low. Tie VTL to GND if unused. VTH: Temperature Threshold High. When VPTAT is above the voltage on VTH, OT is pulled low. Tie VTH to VCC if unused. 2996f 6 LTC2996 Block Diagram 6 VCC 8 VREF 1.8V 200k + 1.2V – VCC 400k 1 VTH – 400k OT CT2 10 + UVLO – 2 5 VTL VPTAT OT/UT PULSE GENERATOR VCC 400k CT1 UT + 1 9 T TO V CONVERTER 4 D– 3 D+ 7 GND 2996 BD 2996f 7 LTC2996 Operation Overview The LTC2996 provides a buffered voltage proportional to the absolute temperature of either an internal or a remote diode (VPTAT) and compares this voltage to thresholds that can be set by external resistor dividers from the on-board reference (VREF). 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 device in a microprocessor or FPGA. Diode Temperature Sensor Temperature measurements are conducted by measuring the voltage of either an internal or an external diode with multiple test currents. The relationship between diode voltage VD and diode current ID can be solved for absolute Temperature in degrees Kelvin T: T= q VD • η • k ln ID I S where 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. This equation shows a relationship between temperature and voltage dependent on the process depended variable IS. Measuring the same diode (with the same value IS) at two different currents (ID1 and ID2) yields an expression independent of IS: T= q V – VD1 • D2 η •k ID2 ln ID1 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: VD + VERROR = η kT I • ln D + RS • ID I S q The LTC2996 removes this error term from the sensor signal by subtracting a cancellation voltage VCANCEL. A resistance extraction circuit uses one additional current measurement 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 input signal is free from errors due to series resistance. LTC2996 cancels series resistances up to several hundred ohms (see Typical Performance Characteristics curves). Higher series resistances cause the cancelation voltage to saturate. 2996f 8 LTC2996 Applications Information Temperature Measurements Before each conversion, a voltage comparator connected to D+ automatically sets the LTC2996 into external or internal mode. Tying D+ to VCC enables internal mode, where VPTAT represents the die temperature. For VD+ more than 300mV below VCC (typical), the LTC2996 assumes that an external sensor is connected. The LTC2996 continuously measures the sensor diode at different test currents and generates a voltage proportional to the absolute temperature of the sensor at the VPTAT pin. The voltage at VPTAT is updated every 3.5ms. The gain of VPTAT is calibrated to 4mV/K for the measurement of the internal diode as well as for remote diodes with an ideality factor of 1.004. TKELVIN = VPTAT 4mV/K (η = 1.004) If an external sensor with an ideality factor different from 1.004 is used, the gain of VPTAT will be scaled by the ratio of the actual ideality factor (ηACT) to 1.004. In these cases the temperature of the external sensor can be calculated from VPTAT by: TKELVIN = VPTAT 1.004 • 4mV/K ηACT Temperature in degrees Celsius can be deduced from degrees Kelvin by: TCELSIUS = TKELVIN – 273.15 Choosing an External Sensor The LTC2996 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 manufacturers with a temperature error of typically less than 0.5°C. Some recommended sources are listed in Table 2: Table 2. Recommended Transistors for Use as Temperature Sensors PART NUMBER PACKAGE Fairchild Semiconductor MANUFACTURER MMBT3904 SOT-23 Central Semiconductor CMBT3904 SOT-23 Diodes Inc. MMBT3904 SOT-23 MMBT3904LT1 SOT-23 NXP MMBT3904 SOT-23 Infineon MMBT3904 SOT-23 UMT3904 SC-70 On Semiconductor Rohm Discrete two terminal diodes are not recommended as remote sensing devices as their ideality factor is typically much higher than 1.004. Also, MOS transistors are not suitable as they don’t exhibit the required current to temperature relationship. Furthermore, gold doped transistors (low beta), high frequency and high voltage transistors should be avoided as remote sensing devices. Connecting an External Sensor The anode of the external sensor must be connected to pin D+. The cathode should be connected to D – for best external noise immunity. 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 LTC2996 to suppress external noise. Recommended shielding and PCB trace considerations for best noise immunity are illustrated in Figure 1. GND SHIELD TRACE 470pF NPN SENSOR D+ D– LTC2996 GND 2996 F01 Figure 1. Recommended PCB Layout Leakage currents at D+ affect the precision of the remote temperature measurements. 100nA leakage current leads to an additional error of 2°C (see Typical Performance Characteristics). 2996f 9 LTC2996 Applications Information Note that bypass capacitors greater than 1nF will cause settling time errors of the different measurement currents and therefore introduce an error in the temperature measurement (see Typical Performance Characteristics). The LTC2996 compensates series resistance in the measurement path and thereby allows accurate remote temperature measurements even with several meters of distance between the sensor and the device. The cable length between the sensor and the LTC2996 is only limited by the mutual capacitance introduced between D+ and D – which degrades measurement accuracy (see Typical Performance Characteristics). For example, a CAT6 cable with 50pF/m should be kept shorter than ~20m to keep the capacitance less than 1nF. To save wiring, the cathode of the remote sensor can also be connected to remote GND and D – to local GND as shown below. D+ 2N3904 470pF D– LTC2996 GND 2996 F02 Figure 2. Single Wire Remote Temperature Sensing The temperature measurement of LTC2996 relies only on differences between the diode voltage at multiple test circuits. Therefore DC offsets smaller than 300mV between remote and local GND do not impact the precision of the temperature measurement. The cathode of the sensor can accommodate modest ground shifts across a system which is beneficial in applications where a good thermal connectivity of the sensor to a device whose temperature is to be monitored (shunt resistor, coil, etc.) is required. Care must be taken if the potential difference between the cathode and D – does not only contain DC but also AC components. Noise around odd multiples of 6kHz (±20%) is amplified by the measurement algorithm and converted to a DC offset in the temperature measurement (see Typical Performance Characteristics). The LTC2996 can withstand up to ±4kV of electrostatic discharge (ESD, human body model). ESD beyond this voltage can damage or degrade the device including lowering the remote sensor measurement accuracy due to increased leakage currents on D+ or D –. To protect the sensing inputs against larger ESD strikes, external protection can be added using TVS diodes to ground (Figure 3). 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 curves). 10Ω MMBT3904 10Ω D+ LTC2996 220pF D– GND PESD5Z6.0 2996 F03 Figure 3. Increasing ESD Robustness with TVS Diodes To make the connection of the cable to the IC polarity insensitive during installation, two sensor transistors with opposite polarity at the end of a two wire cable can be used as shown on Figure 4. D+ MMBT3904 LTC2996 470pF D– GND 2995 F04 Figure 4. Polarity Insensitive Remote Diode Sensor Again, care must be taken that the leakage current of the second transistor does not degrade the measurement accuracy. 2996f 10 LTC2996 Applications Information Output Noise Filtering The VPTAT output typically exhibits 0.6mV 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: t AVG 2 [°C Hz ] 0.01 = TNOISE where t AVG is the averaging time and TNOISE the desired temperature noise in °C RMS. For example, if the desired noise performance is 0.01°C RMS, set the averaging time to one second. See Typical Performance Characteristics. The threshold voltages at VTL and VTH can be set with the 1.8V reference voltage (VREF) and a resistive divider as shown in Figure 5. VREF = 1.8V VPTAT SLOPE = η ACT 1.004 •4 mV K 1.8V VT2 The LTC2996 continuously compares the voltage at VPTAT to the voltages at the pins VTH and VTL to detect either an overtemperature (OT) or undertemperature (UT) condition. The VTH comparator output drives the open-drain logic output pin OT and the VTL comparator output drives the open-drain logic output pin UT. The voltage at VPTAT must exceed a threshold for five consecutive temperature update intervals (3.5ms each) before the respective output pin is pulled low. Once the VPTAT voltage crosses the threshold with an additional 20mV of hysteresis, the respective output pin is released after a single update interval. Temperature Monitor Design Example The LTC2996 can be configured to give an alert if the temperature of the internal sensor falls below 0°C or rises above 90°C. Tie the D+ pin to VCC to select the internal sensor. The voltages at VTL and VTH are set to: mV VTL =(0K + 273.15K) • 4 = 1.093V K Temperature Thresholds RTC Temperature Monitoring VTH =(90K + 273.15K) • 4 When VPTAT falls below 1.093V, UT is pulled low. Once the temperature rises again and VPTAT reaches 1.093V plus a hysteresis of 20mV, UT is released high again. Accordingly, OT is pulled low if temperature increases to 90°C as VPTAT reaches 1.453V and is released high if VPTAT drops again below 1.433V. RTB VT1 O.8V RTA O 200K T1 T2 450K T 2996 F05 Figure 5. Temperature Thresholds The following design procedure can be used to size the resistive divider. 1. Calculate Threshold Voltages: VTL = T1• 4 mV ηACT • K 1.004 VTH = T2 • 4 mV ηACT • K 1.004 mV = 1.453V K 2996f 11 LTC2996 Applications Information where ηACT denotes the actual ideality factor if an external sensor is used and T1 and T2 are the desired threshold temperatures in degrees Kelvin. In the Temperature Monitor example discussed earlier with thresholds at VTL = 0°C and VTH = 90°C and a desired reference current of 10μA, the required values for RTA, RTB and RTC can be calculated as : 2.Choose RTA to obtain the desired VTL threshold for a desired current through the resistive divider (IREF): R TA = VTL IREF 3.Choose RTB to obtain the desired VTH threshold: R TB = VTH – VTL IREF R TA = 1.093V = 109.3K 10µA R TB = 1.453V – 1.093V = 36K 10µA R TC = 1.8V – 1.453V = 34.7K 10µA 4.Finally RTC is determined by: R TC = 1.8V – VTH IREF 3.3V D+ VCC LTC2996 VCC + VREF 1.8V VCC 400k 1.2V OT – 200k RTC 400k VCC VTH – 400k + RTB – VTL RTA UVLO OT/UT PULSE GENERATOR UT + VPTAT T/V D– GND 2996 F06 Figure 6. Monitoring Internal Temperature 2996f 12 LTC2996 Applications Information Remote Temperature Monitor with Overtemperature and Undertemperature Thresholds 2.25V TO 5.5V 0.1µF 1.8V VREF 43k VCC OT T > 70°C OT LTC2996 UT VTH 36k UT T < –20°C 4mV/K VPTAT VTL 102k TEMPERATURE CONTROL SYSTEM D+ 470pF MMBT3904 D– GND 2996 TA02 ASIC/FPGA/Processor Temperature Monitor 2.25V TO 5.5V 0.1µF 1.8V VREF 20.5k VCC OT OT T > 125°C LTC2996 UT T < 30°C UT VTH 38.3k 121k INT2 CPU/ FPGA/ ASIC VPTAT VTL INT1 D+ 470pF GND INTERNAL DIODE D– 2996 TA03 Analog Heater Controller 5V 1.8V 30.9k 40.2k VREF 1.09V 1.49V VCC 0.1µF 10Ω RHEATER VPTAT LTC2996 VTH OT VTL D+ 110k HIGH IF T < 0°C MMBT3904 B6015L12F IRF3708 470pF D– GND UT HIGH IF T < 100°C 2N7000 2996 TA04 2996f 13 LTC2996 Typical Applications Battery Stack Temperature Supervisor 2.25V TO 5.5V 0.1µF VCC VREF LTC2996 D+ TALERT 43.2k VTH UT VTL VPTAT BATTERY SUPERVISOR 10k OT INT 28k 110k GND D– LOW IF TEMPERATURE OF ANY CELL TCELL > 70°C OR TCELL < 0°C 0.1µF VCC VREF LTC2996 D+ OT 43.2k VTH UT VTL VPTAT 28k 110k GND D– 2996 TA05 2996f 14 LTC2996 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1699 Rev C) 0.70 ±0.05 3.55 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC 2.38 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ±0.10 (4 SIDES) R = 0.125 TYP 6 0.40 ±0.10 10 1.65 ±0.10 (2 SIDES) PIN 1 NOTCH R = 0.20 OR 0.35 × 45° CHAMFER PIN 1 TOP MARK (SEE NOTE 6) 0.200 REF 0.75 ±0.05 0.00 – 0.05 5 1 (DD) DFN REV C 0310 0.25 ±0.05 0.50 BSC 2.38 ±0.10 (2 SIDES) BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2). CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT 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 2996f 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. 15 LTC2996 Typical Application Celsius Thermometer and 20°C to 25°C Thermostat 5V 220V AC 5LPCV24110 0.1µF VCC D+ MMBT3904 OT LTC2996 1.8V D– VPTAT GND 4mV/K VTL VTH VREF 118k 150k HEATER UT 470pF 0.1µF – 100k 1k + 62k 143k 1.8k 5V LTC1077 VOLTMETER 10mV/°C 0V AT 0°C 215mV CORRESPONDS TO 21.5°C 2996 TA06 1µF 63.4k Related Parts PART NUMBER DESCRIPTION COMMENTS LTC2990 Quad I2C Voltage, Current and Temperature Monitor Measures Voltage, Current, Internal Temperature and/or Two Remote Diode Temperatures, ±0.5°C (Typ) Accuracy, 0.06°C Resolution, I2C Interface LTC2991 Octal I2C Voltage, Current and Temperature Monitor Measures Voltage, Current, Internal Temperature and/or Four Remote Diode Temperatures, ±0.7°C (Typ), 0.06°C Resolution, I2C Interface, PWM Output LTC2995 Temperature Sensor and Voltage Monitor with Alert Outputs Monitors Temperature and Two Voltages, Adjustable Thresholds, Open Drain Alert Outputs, Temperature to Voltage Output with Integrated 1.8V Reference, ±1°C (Max) Accuracy LTC2997 Remote/Internal Temperature Sensor Converts Remote Sensor or Int. Diode Temperature to Analog Voltage, Integrated 1.8V Reference, ±1°C (Max) Accuracy LTC1077 Micropower, Single Supply, Precision Op Amp 60µA Supply Current, 40µV Offset, Low Noise 2996f 16 Linear Technology Corporation LT 0712 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2012