AD22105AR

FEATURES FUNCTIONAL BLOCK DIAGRAM User-programmable temperature setpoint ±2.0°C maximum ambient setpoint accuracy 4.1°C typical hysteresis Wide supply range: 2.7 V to 7.0 V Wide temperature range: −40°C to +150°C Low power dissipation AD22105 APPLICATIONS Industrial process control Thermal control systems CPU monitoring Computer thermal management circuits Fan control Handheld/portable electronic equipment RPULL–UP 1 OUT 2 GND 3 NC 4 200kΩ SETPOINT TEMPERATURE SENSOR 8 NC 7 VS 6 RSET 5 NC 02099-001 Data Sheet Low Voltage, Resistor-Programmable, Thermostatic Switch AD22105 Figure 1. GENERAL DESCRIPTION The AD22105 is a solid state thermostatic switch. Requiring only one external programming resistor, the AD22105 can be set to switch accurately at any temperature in the −40°C to +150°C wide operating range. Using a novel circuit architecture, the AD22105 asserts an open-collector output when the ambient temperature exceeds the user-programmed setpoint temperature. The AD22105 has approximately 4°C of hysteresis, which prevents rapid thermal on and off cycling. The AD22105 operates on a single power supply voltage from 2.7 V to 7.0 V, facilitating operation in battery-powered applications as well as in industrial control systems. Because of low power dissipation (230 µW at 3.3 V), self heating errors are minimized, and battery life is maximized. An optional internal 200 kΩ pull-up resistor is included to facilitate driving light loads such as complementary metal–oxide semiconductor (CMOS) inputs. Alternatively, a low power light emitting diode (LED) indicator can be driven directly. Rev. A Document Feedback 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 ©1996–2018 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com AD22105 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Applications ....................................................................................... 1 Effect of Resistor Tolerance and Thermal Drift on Setpoint Accuracy .........................................................................................8 General Description ......................................................................... 1 Hysteresis and Self Heating ..........................................................9 Functional Block Diagram .............................................................. 1 Output Section ...............................................................................9 Revision History ............................................................................... 2 Mounting Considerations ............................................................9 Specifications..................................................................................... 3 Thermal Environment Effects .....................................................9 Absolute Maximum Ratings ............................................................ 4 Using the AD22105 as a Cooling Setpoint Detector ................9 Thermal Resistance ...................................................................... 4 Applications Information .............................................................. 10 ESD Caution .................................................................................. 4 Electromagnetic Interference (EMI) Suppression ................. 10 Pin Configuration and Function Descriptions ............................. 5 Leakage at the RSET Pin............................................................... 10 Typical Performance Characteristics ............................................. 6 Outline Dimensions ....................................................................... 11 Theory of Operation ........................................................................ 8 Ordering Guide .......................................................................... 11 The Setpoint Resistor ................................................................... 8 REVISION HISTORY 10/2018—Rev. 0 to Rev. A Update Format .................................................................... Universal Changes to Features Section............................................................ 1 Changed Product Description Section to Theory of Operation Section ................................................................................................ 8 Changed Application Hint Section to Applications Information Section .............................................................................................. 10 Updated Outline Dimensions ....................................................... 11 Changes to Ordering Guide .......................................................... 11 1/1996—Revision 0: Initial Version Rev. A | Page 2 of 11 Data Sheet AD22105 SPECIFICATIONS Supply voltage (VS) = 3.3 V, TA = 25°C, and load resistor (RLOAD) = internal 200 kΩ, unless otherwise noted. Table 1. Parameter TEMPERATURE ACCURACY Ambient Setpoint Accuracy Temperature Setpoint Accuracy Power Supply Rejection HYSTERESIS OPEN-COLLECTOR OUTPUT Output Low Voltage POWER SUPPLY Supply Voltage Range Supply Current Output Low Output High INTERNAL PULL-UP RESISTOR TURN-ON SETTLING TIME Test Conditions/Comments ACC ACCT PSR HYS −40°C ≤ TA ≤ +125°C 2.7 V 1 < VS < 7.0 V VOL Sink current (ISINK) = 5 mA Min Typ Max Unit ±0.5 ±2.0 ±3.0 ±0.15 °C °C °C/V °C 400 mV 2.7 7.0 V 140 120 90 260 µA µA kΩ µs ±0.05 4.1 250 VS ISON ISOFF RPULL-UP tON The AD22105 operates at voltages as low as 2.2 V. RSET = 39MΩ °C –90.3kΩ TSET (°C) + 281.6°C 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 –50 –25 25 50 75 100 0 SETPOINT TEMPERATURE (°C) Figure 2. Setpoint Resistor Values Rev. A | Page 3 of 11 125 150 02099-003 RSET (kΩ) 1 Symbol 200 5 AD22105 Data Sheet ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE Table 2. Parameter Maximum Supply Voltage Maximum Output Voltage (RPULL-UP) Maximum Output Current (OUT) Operating Temperature Range Dice Junction Temperature Storage Temperature Range Lead Temperature (Soldering, 10 sec) Thermal performance is directly linked to PCB design and operating environment. Careful attention to PCB thermal design is required. Ratings 11 V 11 V 10 mA −40°C to +150°C 160°C −65°C to +160°C 300°C Table 3. Thermal Resistance Stresses at or above those listed under Absolute Maximum Ratings may cause permanent damage to the product. This is a stress rating only; functional operation of the product at these or any other conditions above those indicated in the operational section of this specification is not implied. Operation beyond the maximum operating conditions for extended periods may affect product reliability. Package SOIC_N (R-8) Moving Air Without Heat Sink2 Still Air Without Heat Sink θJA (°C/W) τ (sec)1 100 190 3.5 15 The time constant is defined as the time to reach 63.2% of the final temperature change. 2 1200 cubic feet per minute (CFM) 1 ESD CAUTION Rev. A | Page 4 of 11 Data Sheet AD22105 RPULL-UP 1 8 NC OUT 2 AD22105 7 VS GND 3 TOP VIEW (Not to Scale) 6 RSET NC 4 5 NC NC = NO CONNECT 02099-004 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Figure 3. Pin Configuration Table 4. Pin Function Descriptions Pin No. 1 2 3 4, 5, 8 6 7 Mnemonic RPULL-UP OUT GND NC RSET VS Description Internal 200 kΩ Pull-Up Resistor (Optional). Device Output. Ground. No Connect. Temperature Setpoint Resistor. Supply Voltage. VS must be between 2.7 V and 7.0 V. Rev. A | Page 5 of 11 AD22105 Data Sheet TYPICAL PERFORMANCE CHARACTERISTICS 4.4 4 GUARANTEED LIMIT (+) 3 4.2 HYSTERESIS (°C) ERROR (°C) 2 1 0 –1 4.0 3.8 3.6 –2 3.4 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 3.2 –50 02099-005 –4 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 02099-008 GUARANTEED LIMIT (–) –3 Figure 7. Hysteresis vs. Temperature, Setpoint Figure 4. Error vs. Temperature, Setpoint 2.0 ±0.1 ±0.3 SETPOINT ERROR (°C) SETPOINT ERROR (°C/%) 1.5 ±0.5 ±0.7 +125°C 1.0 0.5 +25°C 0 –40°C –0.5 –1.0 ±0.9 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) –2.0 02099-006 ±1.1 –50 3 4 5 6 7 SUPPLY VOLTAGE (V) Figure 5. Setpoint Error vs. Temperature Due to RSET Tolerance 02099-009 –1.5 Figure 8. Setpoint Error vs. Supply Voltage for Various Temperatures 90 120 VS = 7V 110 SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) 80 VS = 7V 70 VS = 5V 60 VS = 3V 100 VS = 5V 90 80 VS = 3V 50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 150 Figure 6. Supply Current (VS) vs. Temperature, Output Voltage (VOUT) = High Rev. A | Page 6 of 11 60 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) Figure 9. Supply Current vs. Temperature, VOUT = Low 150 02099-010 40 –50 02099-007 70 Data Sheet AD22105 0.4 TA = +125°C 0.2 TA = +25°C 0.1 TA = –40°C 0 10µ 100µ 1m 10m IOUT (A) 150 100 50 02099-011 1µ 200 0 800 1200 FLOW RATE (CFM) Figure 10. VOUT vs. Output Current (IOUT), VOUT = Low Figure 12. Thermal Resistance (θJA) vs. Flow Rate 16 100 90 PERCENTAGE OF FINAL VALUE (%) 14 12 10 8 6 4 80 MOVING AIR (1200cfm) 70 60 STILL AIR 50 40 30 20 10 0 2 0 400 800 FLOW RATE (CFM) Figure 11. Time vs. Flow Rate, Thermal Response 1200 02099-012 TIME (Seconds) 400 0 10 20 30 40 TIME (Seconds) 50 60 02099-014 VOUT (V) 0.3 02099-013 THERMAL RESISTANCE (°C/W) 200 Figure 13. Percentage of Final Value vs. Time, Thermal Response Time Rev. A | Page 7 of 11 AD22105 Data Sheet THEORY OF OPERATION The AD22105 is a single-supply semiconductor thermostat switch that uses a circuit architecture to realize the combined functions of a temperature sensor, setpoint comparator, and output stage all in one IC. By using one external resistor, the AD22105 can be programmed to switch at any temperature selected by the system designer in the −40°C to +150°C range. The internal comparator is designed to switch accurately as the ambient temperature rises past the setpoint temperature. When the ambient temperature falls, the comparator relaxes its output at a somewhat lower temperature than that at which the comparator originally switched. The difference between the switch and unswitched temperatures, known as the hysteresis, is nominally 4°C. THE SETPOINT RESISTOR Determine the setpoint resistor by the following equation: RSET = 39 MΩ °C TSET (°C ) + 281.6°C − 90.3 kΩ (1) Connect the setpoint resistor directly between the RSET pin and the GND pin. If a ground plane is used, connect the resistor directly to this plane at the closest available point. The setpoint resistor, RSET, can be almost any resistor type. However, the resistor initial tolerance and thermal drift affects the accuracy of the programmed switching temperature. For most applications, a 1% metal film resistor provides the best tradeoff between cost and accuracy. Calculations for computing an error budget are found in the Effect of Resistor Tolerance and Thermal Drift on Setpoint Accuracy section. After RSET is calculated, the calculated value does not agree with readily available standard resistors of the chosen tolerance. To achieve an RSET value as close as possible to the calculated value, a compound resistor can be constructed by connecting two resistors in series or in parallel. To conserve cost, one moderately precise resistor and one lower precision resistor can be combined. If the moderately precise resistor provides most of the necessary resistance, the lower precision resistor can provide a fine adjustment. Consider an example where the closest standard 1% resistor has only 90% of the value required for RSET. If a 5% series resistor is used for the remainder, the tolerance of the resistor only adds 5% of 10% or 0.5% additional error to the combination. Likewise, the 1% resistor only contributes 90% of 1% or 0.9% error to the combination. These two contributions are additive, resulting in a total compound resistor tolerance of 1.4%. EFFECT OF RESISTOR TOLERANCE AND THERMAL DRIFT ON SETPOINT ACCURACY Figure 4 shows the typical accuracy error in setpoint temperature as a function of the programmed setpoint temperature. This curve assumes an ideal resistor for RSET. Figure 5 can be used to calculate additional setpoint error as a function of resistor tolerance. Figure 5 shows additional error beyond the initial accuracy error of the device and must be added to the value found in Table 1. For example, consider using the AD22105 programmed to switch at 125°C. Figure 5 indicates that at +125°C, the additional error is approximately −0.2°C/% of RSET. If a 1% resistor (of exactly correct value) is chosen, the additional error is −0.2°C/% × 1% or −0.2°C. If the closest standard resistor value is 0.6% away from the calculated value, the total error is 0.6% for the nominal value and 1% for the tolerance or 1.006 × 1. 01 or 1.01606 (about 1.6%). The closest resistor value differing slightly from the calculated value can lead to an additional setpoint error as high as 0.32°C. For additional accuracy considerations, take the thermal drift of the setpoint resistor into account. For example, consider that the drift of the metal film resistor is 100 ppm/°C. Because this drift is usually referred to 25°C, the setpoint resistor can be in error by an additional 100 ppm/°C × (125°C − 25°C) or 1%. Using a setpoint temperature of 125°C, this error source adds an additional −0.2°C (for positive drift) making the overall setpoint error potentially −0.52°C higher than the original accuracy error. To combine and calculate the initial tolerance and thermal drift effects of the setpoint resistor use the following equation: RMAX = RNOM × (1 + ε) × (1 + TC × (TSET − 25°C)) where: RMAX is the worst case value that the setpoint resistor can be at TSET. RNOM is the standard resistor with a value closest to the desired RSET. ε is the 25°C tolerance of the chosen resistor (usually 1%, 5%, or 10%). TC is the temperature coefficient of the available resistor. TSET is the desired setpoint temperature. After calculation, compare RMAX to the desired RSET from Equation 1. The required value of RSET at a TSET of 125°C is 5.566 kΩ. If the nearest standard resistor value is 5.600 kΩ, its worst case maximum value at +125°C is 5.713 kΩ, which is +2.6% higher than RSET, leading to a total additional error of −0.52°C beyond that given in Table 1. Rev. A | Page 8 of 11 Data Sheet AD22105 HYSTERESIS AND SELF HEATING THERMAL ENVIRONMENT EFFECTS The actual value of hysteresis generally has a minor dependence on the programmed setpoint temperature, as shown in Figure 7. Furthermore, the hysteresis can be affected by self heating if the device is driving a heavy load. For example, if the device is driving a load of 5 mA at an output voltage (given by Figure 10) of 250 mV, the additional power dissipation is approximately 1.25 mW. With a θJA of 190°C/W in still air, the internal die temperature is 0.24°C higher than ambient, leading to an increase of 0.24°C in hysteresis. In the presence of a heat sink or a turbulent environment, the additional hysteresis is less. The thermal environment in which the AD22105 is used determines two performance traits: the effect of self heating on accuracy and the response time of the sensor to rapid changes in temperature. In the first case, a rise in the IC junction temperature above the ambient temperature is a function of two variables: the power consumption of the AD22105 and the thermal resistance between the chip and the ambient environment, θJA. Self heating error can be derived by multiplying the power dissipation by θJA. Because errors of this type can vary widely for surroundings with different heat sinking capacities, it is necessary to specify θJA under several conditions. OUTPUT SECTION The output of the AD22105 is the collector of the negative positive negative (NPN) transistor. When the ambient temperature of the device exceeds the programmed setpoint temperature, this transistor is activated, causing its collector to become a low impedance. A pull-up resistor, such as the internal 200 kΩ provided, is needed to observe a change in the output voltage. For versatility, the optional pull-up resistor is not permanently connected to the output pin. Instead, this resistor is undedicated and connects from the VS pin to the RPULL-UP pin. To use RPULL-UP, a single connection must be made from the RPULL-UP pin to the OUT pin. The 200 kΩ pull-up resistor can drive CMOS loads because essentially no static current is required at these inputs. When driving low power Schottky (LS) and other bipolar family logic inputs, a parallel resistor may be necessary to supply the 20 µA to 50 µA high level input current (IIH) specified for such devices. To determine the current required, consult the appropriate manufacturer data sheet. When the output is switched, indicating an over temperature condition, the output is capable of pulling down with 10 mA at a voltage of about 375 mV, which allows a fanout of 2 with standard bipolar logic and 20 with LS family logic. Low power indicator LEDs (up to 10 mA) can be driven directly from the output pin of the AD22105. In most cases, a small series resistor (usually of several hundred ohms) is required to limit the current to the LED and the output transistor of the AD22105. MOUNTING CONSIDERATIONS If the AD22105 is thermally attached and properly protected, it can be used in any measuring situation where the maximum range of temperatures encountered is between −40°C and +150°C. Because plastic IC packaging technology is employed, excessive mechanical stress must be avoided when fastening the device with a clamp or screw on the heat tab. Thermally conductive epoxy or glue is recommended for typical mounting conditions. In wet or corrosive environments, use an electrically isolated metal or ceramic well to protect the AD22105. Table 3 shows how the magnitude of self heating error varies relative to the environment. A typical device dissipates about 230 µW at room temperature with a 3.3 V supply and negligible output loading. In still air, without a heat sink, Table 3 indicates a θJA of 190°C/W, which yields a temperature rise of 0.04°C. Thermal rise of the die is considerably less in an environment of turbulent or constant moving air or if the device is in direct physical contact with a solid (or liquid) body. Response of the AD22105 internal die temperature to abrupt changes in ambient temperatures can be modeled by a single time constant exponential function. Figure 12 shows the typical response for moving and still air. The time constant, τ (time to reach 63.2% of the final value), is dependent on θJA and the thermal capacities of the chip and the package. Table 3 lists the effective τ for moving and still air. Copper PCB connections were neglected in the analysis. However, these connections sink or conduct heat directly through the AD22105 solder plated copper leads. When faster response is required, use a thermally conductive grease or glue between the AD22105 and the surface temperature being measured. USING THE AD22105 AS A COOLING SETPOINT DETECTOR The AD22105 detects transitions from higher temperatures to lower temperatures by programming the setpoint temperature 4°C greater than the desired trip point temperature. The 4°C is necessary to compensate for the nominal hysteresis value designed into the device. A more precise value of the hysteresis can be obtained from Figure 7. In this mode, the logic state of the output indicates a high for under temperature conditions. The total device error is slightly greater than the specification value due to the uncertainty in hysteresis. Rev. A | Page 9 of 11 AD22105 Data Sheet APPLICATIONS INFORMATION LEAKAGE AT THE RSET PIN Figure 14 shows the typical application circuit. Leakage currents at the RSET pin, such as those generated from a moist environment or PCB contamination, can have an adverse effect on the programmed setpoint temperature of the AD22105. Depending on the leakage source, leakage current can flow into or out of the RSET pin. Consequently, the actual setpoint temperature may be higher or lower than the intended setpoint temperature by about 1°C for each 75 nA of leakage. With a 5 V power supply, an isolation resistance of 100 MΩ creates 50 nA of leakage current, resulting in a setpoint temperature error of about 0.7°C (the RSET pin is near ground potential). Place a guard ring around the RSET node to protect against leakage from the power supply pin (as shown in Figure 15). +2.7V TO +7.0V 8 7 6 5 AD22105 2 3 4 02099-002 1 RSET OUT VS Figure 14. Typical Application Circuit ELECTROMAGNETIC INTERFERENCE (EMI) SUPPRESSION C1 Rev. A | Page 10 of 11 RSET GND PIN 1 OUT Figure 15. Suggested PCB Layout 02099-015 Noisy environments may couple electromagnetic energy into the RSET node causing the AD22105 to falsely trip or untrip. Noise sources, which typically come from fast rising edges, can be coupled into the device capacitively. Furthermore, if the output signal is close to the RSET pin, energy can couple from the OUT pin to the RSET pin, potentially causing oscillation. Stray capacitance can come from several places such as IC sockets, multiconductor cables, and PCB traces. In some cases, constructing a Faraday shield around the RSET pin can correct this; for example, by using a shielded cable with the shield grounded. However, for best performance, avoid cables and directly solder the AD22105 to a PCB whenever possible. Figure 15 shows a sample PCB layout with low inter pin capacitance and Faraday shielding. If stray capacitance is unavoidable, and interference or oscillation occurs, connect a low impedance capacitor from the RSET pin to the GND pin. This capacitor must be considerably larger than the estimated stray capacitance. Typically, several hundred picofarads corrects the problem. Data Sheet AD22105 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 1 5 4 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) COPLANARITY 0.10 SEATING PLANE 6.20 (0.2441) 5.80 (0.2284) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) 0.31 (0.0122) 0.50 (0.0196) 0.25 (0.0099) 45° 8° 0° 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) COMPLIANT TO JEDEC STANDARDS MS-012-AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. 012407-A 8 4.00 (0.1574) 3.80 (0.1497) Figure 16. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) ORDERING GUIDE Model 1 AD22105ARZ AD22105ARZ-REEL AD22105ARZ-REEL7 1 Temperature Range −40°C to +150°C −40°C to +150°C −40°C to +150°C Package Description 8-Lead Standard Small Outline Package [SOIC_N] 8-Lead Standard Small Outline Package [SOIC_N] 8-Lead Standard Small Outline Package [SOIC_N] Z = RoHS Compliant Part. ©1996–2018 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D02099-0-10/18(A) Rev. A | Page 11 of 11 Package Option R-8 R-8 R-8