Low Cost, 2.7 V to 5.5 V, Pin-Selectable Temperature Switches in SOT-23 ADT6401/ADT6402 FEATURES FUNCTIONAL BLOCK DIAGRAM VCC GND 4 5 ADT6401 Σ-Δ TEMPERATURE-TODIGITAL CONVERTER COMPARATOR 6 S2 1 S1 2 S0 3 TRIP POINT AND HYSTERESIS DECODING TOVER/TUNDER 2ºC/10ºC 07415-001 ±0.5°C (typical) threshold accuracy Pin-selectable trip points from −45°C to +5°C in 10°C increments (undertemperature) 45°C to 115°C in 10°C increments (overtemperature) Maximum operating temperature of 125°C Open-drain output (ADT6401) Push-pull output (ADT6402) Pin-selectable hysteresis of 2°C and 10°C Supply current of 30 μA (typical) Space-saving, 6-lead SOT-23 package APPLICATIONS Figure 1. Medical equipment Automotive Cell phones Hard disk drives Personal computers Electronic test equipment Domestic appliances Process control GENERAL DESCRIPTION The ADT6401/ADT6402 are trip point temperature switches available in a 6-lead SOT-23 package. Each part contains an internal band gap temperature sensor for local temperature sensing. When the temperature crosses the trip point setting, the logic output is activated. The ADT6401 logic output is active low and open-drain. The ADT6402 logic output is active high and push-pull. The temperature is digitized to a resolution of 0.125°C (11-bit). The pin-selectable trip point settings are 10°C apart starting from −45°C to +5°C for undertemperature switching, and from 45°C to 115°C for overtemperature switching. When the ADT6401/ADT6402 are used for monitoring temperatures from −45°C to +5°C, the logic output pin becomes active when the temperature goes lower than the selected trip point temperature. These devices typically consume 30 μA of supply current. Hysteresis is pin selectable at 2°C and 10°C. The temperature switch is specified to operate over the supply range of 2.7 V to 5.5 V. 5. 6. 7. 8. 9. When the ADT6401/ADT6402 are used for monitoring temperatures from 45°C to 115°C, the logic output pin becomes active when the temperature goes higher than the selected trip point temperature. PRODUCT HIGHLIGHTS 1. 2. 3. 4. Σ-Δ based temperature measurement gives high accuracy and noise immunity. Wide operating temperature range from −55°C to +125°C. ±0.5°C typical accuracy from −45°C to +115°C. Pin-selectable threshold settings from −45°C to +115°C in 10°C increments. Supply voltage is 2.7 V to 5.5 V. Supply current of 30 μA. Space-saving, 6-lead SOT-23 package. Pin-selectable temperature hysteresis of 2°C or 10°C. Temperature resolution of 0.125°C. Rev. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2008 Analog Devices, Inc. All rights reserved. ADT6401/ADT6402 TABLE OF CONTENTS Features .............................................................................................. 1 Theory of Operation .........................................................................9 Applications ....................................................................................... 1 Circuit Information.......................................................................9 Functional Block Diagram .............................................................. 1 Converter Details ..........................................................................9 General Description ......................................................................... 1 Pin-Selectable Trip Point and Hysteresis ...................................9 Product Highlights ........................................................................... 1 Temperature Conversion ........................................................... 10 Revision History ............................................................................... 2 Applications Information .............................................................. 11 Specifications..................................................................................... 3 Thermal Response Time ........................................................... 11 Absolute Maximum Ratings............................................................ 4 Self-Heating Effects .................................................................... 11 ESD Caution .................................................................................. 4 Supply Decoupling ..................................................................... 11 Pin Configurations and Function Descriptions ........................... 5 Temperature Monitoring ........................................................... 11 Typical Performance Characteristics ............................................. 6 Outline Dimensions ....................................................................... 12 Typical Application Circuits............................................................ 8 Ordering Guide .......................................................................... 12 REVISION HISTORY 5/08—Revision 0: Initial Version Rev. 0 | Page 2 of 12 ADT6401/ADT6402 SPECIFICATIONS TA = −55°C to +125°C, VCC = 2.7 V to 5.5 V, open-drain RPULL-UP = 10 kΩ, unless otherwise noted. Table 1. Parameter TEMPERATURE SENSOR AND ADC Threshold Accuracy Min ADC Resolution Temperature Conversion Time Update Rate Temperature Threshold Hysteresis DIGITAL OUTPUT (OPEN-DRAIN) Output High Current, IOH Output Low Voltage, VOL Typ Max Unit Test Conditions/Comments ±0.5 ±0.5 ±0.5 ±0.5 11 30 600 2 10 ±6 ±4 ±4 ±6 °C °C °C °C Bits ms ms °C °C TA = −45°C to −25°C TA = −15°C to +15°C TA = 35°C to 65°C TA = 75°C to 115°C Time necessary to complete a conversion Conversion started every 600 ms Pin selectable, depends on S0, S1, S2 settings Pin selectable, depends on S0, S1, S2 settings nA V V pF Leakage current, VCC = 2.7 V and VOH = 5.5 V IOL = 1.2 mA, VCC = 2.7 V IOL = 3.2 mA, VCC = 4.5 V RPULL-UP = 10 kΩ IOL = 1.2 mA, VCC = 2.7 V IOL = 3.2 mA, VCC = 4.5 V ISOURCE = 500 μA, VCC = 2.7 V ISOURCE = 800 μA, VCC = 4.5 V 10 V V V V pF 5.5 50 V μA 10 0.3 0.4 10 Output Capacitance, COUT1 DIGITAL OUTPUT (PUSH-PULL) Output Low Voltage, VOL Output High Voltage, VOH Output Capacitance, COUT1 POWER REQUIREMENTS Supply Voltage Supply Current 1 0.3 0.4 0.8 × VCC VCC − 1.5 2.7 30 Guaranteed by design and characterization. Rev. 0 | Page 3 of 12 ADT6401/ADT6402 ABSOLUTE MAXIMUM RATINGS Rating −0.3 V to +7 V −0.3 V to VCC + 0.3 V −0.3 V to +7 V −0.3 V to VCC + 0.3 V 20 mA 20 mA 1.5 kV −55°C to +125°C −65°C to +160°C 150.7°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 0.9 WMAX = (TJMAX − TA2)/θJA 229.6°C/W 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 260°C (+0°C) 20 sec to 40 sec 3°C/sec maximum −6°C/sec maximum 8 minute maximum SOT-23 PD @ 125°C = 0.107W 0 –55 –40 –20 0 20 40 60 80 100 120 –50 –30 –10 10 30 50 70 90 110 125 TEMPERATURE (°C) Figure 2. SOT-23 Maximum Power Dissipation vs. Temperature 1 Values relate to package being used on a standard 2-layer PCB, which gives a worst-case θJA. Refer to Figure 2 for a plot of maximum power dissipation vs. ambient temperature (TA). 2 TA = ambient temperature. 3 Junction-to-case resistance is applicable to components featuring a preferential flow direction, for example, components mounted on a heat sink. Junction-to-ambient resistance is more useful for air-cooled, PCB-mounted components. ESD CAUTION Rev. 0 | Page 4 of 12 07415-002 Parameter VCC to GND S0, S1, S2 Input Voltage to GND Open-Drain Output Voltage to GND Push-Pull Output Voltage to GND Input Current on All Pins Output Current on All Pins ESD rating (HBM) Operating Temperature Range Storage Temperature Range Maximum Junction Temperature, TJMAX 6-Lead SOT-23 (RJ-6) Power Dissipation1 Thermal Impedance3 θJA, Junction-to-Ambient (Still Air) IR Reflow Soldering (RoHS-Compliant Package) Peak Temperature Time at Peak Temperature Ramp-Up Rate Ramp-Down Rate Time 25°C to Peak Temperature MAXIMUM POWER DISSIPATION (W) Table 2. ADT6401/ADT6402 PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS 6 TOVER/TUNDER S2 1 ADT6401 TOP VIEW (Not to Scale) S0 3 5 GND 4 VCC S1 2 07415-003 S1 2 6 TOVER/TUNDER 5 GND 4 VCC ADT6402 S0 3 Figure 3. ADT6401 Pin Configuration TOP VIEW (Not to Scale) 07415-004 S2 1 Figure 4. ADT6402 Pin Configuration Table 3. Pin Function Descriptions Pin Number ADT6401 ADT6402 1 1 2 2 3 3 4 4 5 5 6 N/A Mnemonic S2 S1 S0 VCC GND TOVER/TUNDER N/A TOVER/TUNDER 6 Description Select Pin for Trip Point and Hysteresis Values. Select Pin for Trip Point and Hysteresis Values. Select Pin for Trip Point and Hysteresis Values. Supply Input (2.7 V to 5.5 V). Ground. Open-Drain, Active Low Output. Pull-up resistor required. This pin goes low when the temperature of the part exceeds the pin-selectable threshold. Push-Pull, Active High Output. This pin goes high when the temperature of the part exceeds the pin-selectable threshold. Rev. 0 | Page 5 of 12 ADT6401/ADT6402 TYPICAL PERFORMANCE CHARACTERISTICS 80 SAMPLE SIZE = 300 70 OUTPUT SINK RESISTANCE (Ω) 30 25 20 15 10 5 2.7V –0.5 –0.4 –0.3 –0.2 –0.1 0.1 0.2 0.3 0.4 0.5 TEMPERATURE ACCURACY (°C) 40 5.5V 30 20 0 –80 –60 –40 –20 0 20 40 60 80 100 120 140 TEMPERATURE (°C) Figure 5. Trip Threshold Accuracy Figure 8. Output Sink Resistance vs. Temperature 45 120 40 5V 100 35 TEMPERATURE (°C) 3.3V 30 ICC (µA) 3.3V 50 07415-018 0 60 10 07415-015 PERCENTAGE OF PARTS SAMPLED (%) 35 25 20 15 80 60 40 10 20 –40 –20 0 20 40 60 80 100 120 140 TEMPERATURE (°C) 0 07415-016 0 –60 Figure 6. Operating Supply Current vs. Temperature 1.6 0.8 2.4 3.2 4.0 4.8 12.8 6.4 8.0 9.6 11.2 5.6 7.2 8.8 10.4 12.0 TIME (s) Figure 9. Thermal Step Response in Perfluorinated Fluid 180 140 160 120 140 TEMPERATURE (°C) 2.7V 120 3.3V 100 5.5V 80 60 100 80 60 40 40 0 –80 –60 –40 –20 0 20 40 60 80 100 120 140 TEMPERATURE (°C) 0 0 3.6 7.2 10.8 18.0 25.2 32.4 39.6 46.8 54.0 61.2 14.4 21.6 28.8 36.0 43.2 50.4 57.6 TIME (s) Figure 10. Thermal Step Response in Still Air Figure 7. ADT6402 Output Source Resistance vs. Temperature Rev. 0 | Page 6 of 12 07415-020 20 20 07415-017 OUTPUT SOURCE RESISTANCE (Ω) 0 07415-019 5 ADT6401/ADT6402 11 10°C 10 9 HYSTERESIS (°C) 8 VCC 7 1 VDD = 3.3V 6 5 4 TOVER 3 2 2°C 2 CH1 2.0V CH2 2.0V M 10.0ms 50.0kS/s A CH1 1.68V 20.0µs/pt 07415-023 130 TEMPERATURE (°C) 07415-021 120 110 90 100 80 70 60 50 40 30 20 0 10 –10 –20 –30 –40 –60 0 –50 1 Figure 13. ADT6401 Start-Up Delay Figure 11. Hysteresis vs. Trip Temperature 45 40 35 VCC 30 ICC (µA) 1 25 20 15 TOVER –40ºC –10ºC +25ºC +75ºC +120ºC 10 5 CH2 2.0V M 10.0µs 50.0MS/s A CH1 1.68V 20.0ns/pt 0 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 07415-022 CH1 2.0V VCC (V) Figure 14. Operating Supply Current vs. Voltage Over Temperature Figure 12. ADT6401 Start-Up and Power-Down Delay Rev. 0 | Page 7 of 12 07415-024 2 ADT6401/ADT6402 TYPICAL APPLICATION CIRCUITS 3.3V 12V 3.3V 0.1µF 0.1µF 100kΩ VCC VCC ADT6401 S2 MICROPROCESSOR S2 TOVER S1 VCC ADT6402 S1 INT S0 S0 TOVER 07415-011 07415-012 GND GND GND TRIP POINT = 95°C HYSTERESIS = 2°C TRIP POINT = 65°C HYSTERESIS = 10°C Figure 15. Microprocessor Alarm Figure 16. Overtemperature Fan Control 3.3V 0.1µF VCC S2 ADT6402 S1 TOVER OVER TEMPERATURE S0 GND TRIP POINT = +105°C HYSTERESIS = +2°C OUT OF RANGE 0.1µF VCC ADT6402 S2 TUNDER S1 UNDER TEMPERATURE GND TRIP POINT = –35°C HYSTERESIS = +2°C Figure 17. Temperature Window Alarms Rev. 0 | Page 8 of 12 07415-013 S0 ADT6401/ADT6402 THEORY OF OPERATION CIRCUIT INFORMATION PIN-SELECTABLE TRIP POINT AND HYSTERESIS The ADT6401/ADT6402 are 11-bit digital temperature sensors with a 12th bit acting as the sign bit. An on-board temperature sensor generates a voltage precisely proportional to absolute temperature, which is compared to an internal voltage reference and input to a precision digital modulator. The 12-bit output from the modulator is input into a digital comparator, where it is compared with a pin-selectable trip level. The output trip pin is activated if the temperature measured is greater than, or less than, the pin-selectable trip level. Overall accuracy for the ADT6401/ ADT6402 is ±6°C (maximum) from −45°C to +115°C. The temperature trip point and hysteresis values for the ADT6401/ADT6402 are selected using Pin S0, Pin S1, and Pin S2. These three pins can be connected to VCC, tied to GND, or left floating. The ADT6401/ADT6402 decode the inputs on S0, S1, and S2 to determine the temperature trip point and hysteresis value, as outlined in Table 4. The on-board temperature sensor has excellent accuracy and linearity over the entire rated temperature range without needing correction or calibration by the user. The ADT6401 has active low, open-drain output structures that can sink current. The ADT6402 has active high, push-pull output structures that can sink and source current. On power-up, the output becomes active when the first conversion is completed, which typically takes 30 ms. Table 4. Selecting Trip Points and Hysteresis1 The sensor output is digitized by a first-order, ∑-Δ modulator, also known as the charge balance type analog-to-digital converter (ADC). This type of converter utilizes time domain oversampling and a high accuracy comparator to deliver 11 bits of effective accuracy in an extremely compact circuit. CONVERTER DETAILS The Σ-Δ modulator consists of an input sampler, a summing network, an integrator, a comparator, and a 1-bit digital-toanalog converter (DAC). Similar to the voltage-to-frequency converter, this architecture creates a negative feedback loop and minimizes the integrator output by changing the duty cycle of the comparator output in response to input voltage changes. The comparator samples the output of the integrator at a much higher rate than the input sampling frequency; this is called oversampling. Oversampling spreads the quantization noise over a much wider band than that of the input signal, improving overall noise performance and increasing accuracy. The ADT6401 overtemperature/undertemperature output is intended to interface to reset inputs of microprocessors. The ADT6402 is intended for driving circuits of applications, such as fan control circuits. S2 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 Float Float Float Float Float Float Float Float Float 1 S1 0 0 0 1 1 0 Float Float Float 0 0 0 1 1 1 Float Float Float 0 0 0 1 1 1 Float Float Float S0 0 1 Float 0 1 Float 0 1 Float 0 1 Float 0 1 Float 0 1 Float 0 1 Float 0 1 Float 0 1 Float Temperature Trip Point +45°C +55°C +65°C +75°C +85°C +95°C +105°C +115°C +55°C +65°C +75°C +85°C +95°C +105°C +115°C +5°C −5°C −15°C −25°C −35°C −45°C +5°C −5°C −15°C −25°C −35°C −45°C 0 = pin tied to GND, 1 = pin tied to VCC, Float = pin left floating. Rev. 0 | Page 9 of 12 Hysteresis 2°C 2°C 2°C 2°C 2°C 2°C 2°C 2°C 10°C 10°C 10°C 10°C 10°C 10°C 10°C 2°C 2°C 2°C 2°C 2°C 2°C 10°C 10°C 10°C 10°C 10°C 10°C ADT6401/ADT6402 Hysteresis A hysteresis value of 2°C or 10°C can be selected. The digital comparator ensures excellent accuracy for the hysteresis value. Hysteresis prevents oscillation on the output pin when the temperature is approaching the trip point and after the output pin is activated. For example, if the temperature trip is 45°C and the hysteresis selected is 10°C, the temperature must go as low as 35°C before the output deactivates. TEMPERATURE CONVERSION The conversion clock for the part is generated internally. No external clock is required. The internal clock oscillator runs an automatic conversion sequence. During this automatic conversion sequence, a conversion is initiated every 600 ms. At this time, the part powers up its analog circuitry and performs a temperature conversion. This temperature conversion typically takes 30 ms, after which the analog circuitry of the part automatically shuts down. The analog circuitry powers up again 570 ms later, when the 600 ms timer times out and the next conversion begins. The result of the most recent temperature conversion is compared with the factory-set trip point value. If the temperature measured is greater than the trip point value, the output is activated. The output is deactivated once the temperature crosses back over the trip point threshold, plus whatever temperature hysteresis is selected. Figure 18 to Figure 21 show the transfer function for the output trip pin of each generic model. V V TUNDER TOVER HOT TEMP 2°C HYSTERESIS TEMP TTH 10°C HYSTERESIS 2°C HYSTERESIS 07415-006 TTH HOT COLD Figure 18. ADT6401 TOVER Transfer Function 07415-008 COLD 10°C HYSTERESIS Figure 20. ADT6401 TUNDER Transfer Function V V TOVER TUNDER TTH HOT COLD TEMP 2°C HYSTERESIS TTH 10°C HYSTERESIS 2°C HYSTERESIS Figure 19. ADT6402 TOVER Transfer Function Figure 21. ADT6402 TUNDER Transfer Function Rev. 0 | Page 10 of 12 TEMP 07415-009 10°C HYSTERESIS HOT 07415-007 COLD ADT6401/ADT6402 APPLICATIONS INFORMATION The time required for a temperature sensor to settle to a specified accuracy is a function of the thermal mass of the sensor and the thermal conductivity between the sensor and the object being sensed. Thermal mass is often considered equivalent to capacitance. Thermal conductivity is commonly specified using the symbol Q and can be thought of as thermal resistance. It is commonly specified in units of degrees per watt of power transferred across the thermal joint. Thus, the time required for the ADT6401/ADT6402 to settle to the desired accuracy is dependent on the characteristics of the SOT-23 package, the thermal contact established in that particular application, and the equivalent power of the heat source. In most applications, the settling time is best determined empirically. If possible, the ADT6401/ADT6402 should be powered directly from the system power supply. This arrangement, shown in Figure 22, isolates the analog section from the logic-switching transients. Even if a separate power supply trace is not available, generous supply bypassing reduces supply line induced errors. Local supply bypassing consisting of a 0.1 μF ceramic capacitor is advisable to achieve the temperature accuracy specifications. This decoupling capacitor must be placed as close as possible to the ADT6401/ADT6402 VCC pin. TTL/CMOS LOGIC CIRCUITS SELF-HEATING EFFECTS The temperature measurement accuracy of the ADT6401/ ADT6402 can be degraded in some applications due to selfheating. Errors can be introduced from the quiescent dissipation and power dissipated when converting. The magnitude of these temperature errors depends on the thermal conductivity of the ADT6401/ADT6402 package, the mounting technique, and the effects of airflow. At 25°C, static dissipation in the ADT6401/ ADT6402 is typically 99 μW operating at 3.3 V. In the 6-lead SOT-23 package mounted in free air, this accounts for a temperature increase due to self-heating of ΔT = PDISS × θJA = 99 μW × 240°C/W = 0.024°C It is recommended that current dissipated through the device be kept to a minimum because it has a proportional effect on the temperature error. SUPPLY DECOUPLING The ADT6401/ADT6402 should be decoupled with a 0.1 μF ceramic capacitor between VCC and GND. This is particularly important when the ADT6401/ADT6402 are mounted remotely from the power supply. Precision analog products such as the ADT6401/ADT6402 require well-filtered power sources. Because the ADT6401/ADT6402 operate from a single supply, it may seem convenient to tap into the digital logic power supply. Unfortunately, the logic supply is often a switch-mode design, which generates noise in the 20 kHz to 1 MHz range. In addition, fast logic gates can generate glitches that are hundreds of millivolts in amplitude due to wiring resistance and inductance. 0.1µF ADT6401/ ADT6402 POWER SUPPLY 07415-010 THERMAL RESPONSE TIME Figure 22. Separate Traces Used to Reduce Power Supply Noise TEMPERATURE MONITORING The ADT6401/ADT6402 are ideal for monitoring the thermal environment within electronic equipment. For example, the surface-mount package accurately reflects the exact thermal conditions that affect nearby integrated circuits. The ADT6401/ADT6402 measure and convert the temperature at the surface of its own semiconductor chip. When the ADT6401/ ADT6402 are used to measure the temperature of a nearby heat source, the thermal impedance between the heat source and the ADT6401/ADT6402 must be as low as possible. As much as 60% of the heat transferred from the heat source to the thermal sensor on the ADT6401/ADT6402 die is discharged via the copper tracks, package pins, and bond pads. Of the pins on the ADT6401/ADT6402, the GND pin transfers most of the heat. Therefore, to monitor the temperature of a heat source, it is recommended that the thermal resistance between the ADT6401/ ADT6402 GND pin and the GND of the heat source be reduced as much as possible. For example, the unique properties of the ADT6401/ADT6402 can be used to monitor a high power dissipation microprocessor. The ADT6401/ADT6402 device in its SOT-23 package is mounted directly beneath the pin grid array (PGA) package of the microprocessor. The ADT6401/ADT6402 require no external characterization. Rev. 0 | Page 11 of 12 ADT6401/ADT6402 OUTLINE DIMENSIONS 2.90 BSC 6 5 4 2.80 BSC 1.60 BSC 1 2 3 PIN 1 INDICATOR 0.95 BSC 1.90 BSC 1.30 1.15 0.90 1.45 MAX 0.50 0.30 0.15 MAX 0.22 0.08 SEATING PLANE 10° 4° 0° 0.60 0.45 0.30 COMPLIANT TO JEDEC STANDARDS MO-178-AB Figure 23. 6-Lead Small Outline Transistor Package [SOT-23] (RJ-6) Dimensions shown in millimeters ORDERING GUIDE Model ADT6401SRJZ-RL71 ADT6402SRJZ-RL71 1 Temperature Range −55°C to +125°C −55°C to +125°C Package Description 6-Lead SOT-23 6-Lead SOT-23 Z = RoHS Compliant Part. ©2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D07415-0-5/08(0) Rev. 0 | Page 12 of 12 Package Option RJ-6 RJ-6 Ordering Quantity 3,000 3,000 Branding T30 T32