NCT51, NCT52 Ultra Small Temperature Switch with Pin-Selectable Hysteresis The NCT51 and NCT52 are SOT–23 temperature switches that require no external components and the design is facilitated with factory–programmed temperature thresholds. A choice of factory–trimmed temperature trip points are available. Pin selectable hysteresis of +2°C or +10°C allows flexibility to the design. These parts typically consume only 17 µA of current and operate over the entire –55°C to +125°C temperature range while offering accuracies of 0.5°C (typ) and 4°C (max). The NCT51 has an open drain, active low output, meant for microprocessor reset control. The NCT52 has a CMOS, active high output designed to drive a logic level MOSFET to turn on a fan or heater element. The NCT51/NCT52 are aimed for hot–temperature monitoring (+45°C to +115°C). These devices assert a logic signal when the temperature goes above the threshold. The NCT51 and NCT52 are offered in three standard temperature thresholds. Available in 5–Pin SOT–23A packages, these parts are ideal for applications requiring high integration, small size, low power and low installed cost. http://onsemi.com 5 4 1 2 SOT–23A SN SUFFIX CASE 1212 3 PIN CONNECTIONS GND 1 5 TOVER (TOVER)* GND 2 HYST 3 4 VCC *For NCT52 Note: 5–Pin SOT–23A is equivalent to EIAJ SC–74A Features • 5–Pin SOT–23A • Factory–Programmed Thresholds from +45°C to +115°C in 10°C • • • • Increments Pin–Selectable +2°C or +10°C Hysteresis 0.5°C (Typ) Threshold Accuracy Over Full Temperature Range No External Components Required 17 µA Supply Current ORDERING INFORMATION See detailed ordering and shipping information in the package dimensions section on page 9 of this data sheet. DEVICE MARKING INFORMATION See general marking information in the device marking section on page 9 of this data sheet. Typical Applications • • • • • • • Thermal Management in PCs and Servers Over Temperature Fail Safe Circuits Simple Fan Controller Temperature Alarms Projectors/Printers Notebook Computers Network Boxes Semiconductor Components Industries, LLC, 2000 September, 2000 – Rev. 0 1 Publication Order Number: NCT51/D NCT51, NCT52 ABSOLUTE MAXIMUM RATINGS* Rating Symbol Value Unit VCC –0.3 to +7.0 V TOVER (NCT51) – –0.3 to +7.0 V TOVER (NCT52) – –0.3 to (VCC +0.3) V All Other Pins – –0.3 to (VCC +0.3) V Input Current (All Pins) – 20 mA Output Current (All Pins) – 20 mA – –55 to +125 °C Tstg –65 to +165 °C Lead Temperature (Soldering, 10 seconds) – +300 °C Power Dissipation (TA = +70°C) (Derate 7.1 mW/°C Above +70°C) – 571 mW Supply Voltage Operating Temperature Range Storage Temperature Range *Static–sensitive device. Unused devices must be stored in conductive material. Protect devices from static discharge and static fields. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. Exposure to Absolute Maximum Rating Conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS VCC = +2.7 V to +5.5 V, RPULL–UP = 100 KΩ (NCT51 only), CCOUPLING = 100 pF from VCC to GND, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C. Characteristics Supply Voltage Range Test Conditions Symbol Min Typ Max Unit – VCC 2.7 – 5.5 V – ICC – 17 40 µA Temperature Threshold Accuracy (Note 1.) +45°C to +65°C +75°C to +115°C ∆TTH –4.0 –6.0 0.5 0.5 4.0 6.0 °C Temperature Threshold Hysteresis HYST = GND HYST = VCC THYST – – 2.0 10 – – °C HYST Input Threshold – VIH 0.8 x VCC – – V HYST Input Threshold – VIL – – 0.2 x VCC V ISOURCE = 500 µA, VCC 2.7 V (NCT52 Only) ISOURCE = 800 µA, VCC 4.5 V (NCT52 Only) VOH 0.8 x VCC – – V VCC –1.5 – – Output Voltage Low ISINK = 1.2 mA, VCC 2.7 V ISINK = 3.2 mA, VCC 4.5 V VOL – – – – 0.3 0.4 V Open–Drain Output Leakage Current VCC = 2.7 V, VTOVER = 5.5 V (NCT51 Only) – – 10 – nA Supply Current Output Voltage High 1. The NCT51 and NCT52 are available with internal, factory–programmed temperature trip thresholds from +45°C to +115°C in +10°C increments. http://onsemi.com 2 NCT51, NCT52 PIN DESCRIPTION NCT51 NCT52 Name Description 1,2 1,2 GND Ground. Ground both pins together close to the chip. Pin 2 provides the lowest thermal resistance to the die. 3 3 HYST Hysteresis Input. Connect HYST to GND for +2°C hysteresis, or connect to VCC for +10°C hysteresis. 4 4 VCC 5 – TOVER Open–Drain, Active–Low Output. TOVER goes low when the die temperature exceeds the factory–programmed temperature threshold. Connect to a 100 KΩ pull–up resistor. May be pulled up to a voltage higher than VCC. – 5 TOVER Push/Pull Active–High Output. TOVER goes high when the die temperature exceeds the factory–programmed temperature threshold. – – TUNDER Open–Drain, Active–Low Output. TUNDER goes low when the die temperature goes below the factory–programmed temperature threshold. Connect to a 100 KΩ pull–up resistor. May be pulled up to a voltage higher than VCC. – – TUNDER Push/Pull Active–High Output. TUNDER goes high when the die temperature is below the factory–programmed temperature threshold. Supply Input (+2.7 V to +5.5 V). Recommend 100 pF or greater Coupling capacitor from VCC to GND. Typical Operating Circuit The NCT51 is intended for applications with a microprocessor reset input. The NCT52 is intended for applications of turning on a fan or heater element. +2.7 V to +5.5 V Hysteresis Input 100 pF VCC VCC NCT52 µP TOVER To prevent the output from “chattering’’ at or near the trip point temperature, a selectable HYST input pin is provided. Hysteresis can be externally selected at 2°C (HYST = GND) or 10°C (HYST = VDD) by means of the CMOS compatible HYST input pin. Do not let the HYST pin float as this could cause increase supply current. The hysteresis does not depend on the part’s programmed trip threshold. INT GND GND HYST Table 1. Factory–Programmed Threshold Range GND Part Number Threshold (TTH) Range NCT51 +45°C TTH +115°C NCT52 +45°C TTH +115°C Thermal Considerations With a very low 17 µA supply current, the NCT51 and NCT52 dissipates very little power. Thus, the die temperature is basically the same as the package temperature. To minimize the error in temperature readings, the load current should be limited to a few milliamps. As an example, the typical thermal resistance of a 5–Pin SOT–23A package is 140°C/W. If the NCT51 had to sink 1.0 mA, and the output voltage is guaranteed to be less than 0.3 V, then an additional 0.3 mW of power is dissipated within the IC. This corresponds to a 0.042°C rise in die temperature in the 5–Pin SOT–23A. DETAILED DESCRIPTION The NCT51 and NCT52 integrate a temperature sensor with a factory–programmed threshold switch. A logic signal is asserted when the die temperature crosses the factory programmed threshold. An external hysteresis input pin allows the user to select either 2°C or 10°C hysteresis to give further flexibility to the design of the application. The NCT51 and NCT52 are intended for a temperature range from 45°C to 115°C in a 10°C increment. The NCT51 has an open drain output and the NCT52 has a push/pull output stage. http://onsemi.com 3 NCT51, NCT52 package can be placed directly under the socketed microprocessor for improved thermal contact. Temperature monitoring accuracy depends on the thermal resistance between the device being monitored and the temperature switch die. Heat flows primarily through the leads onto the die. Pin 2 provides the lowest thermal resistance to the die. To achieve the best temperature monitoring results, the NCT51 and NCT52 should be placed closest to the device being monitored. In addition, a short and wide copper trace from Pin 2 to the device should be used. In some cases, the 5–Pin SOT–23A APPLICATIONS The NCT51 has an open drain output and is therefore intended to interface as a microprocessor reset input. Moreover, the combination of these two devices can be used to implement a temperature window alarm by wire–ORing the outputs and using an external pull up resistor. (See Figure 1) +5 V RPULL–UP 100 k Temperature Out of Range 100 pF 100 pF VCC VCC NCT51SN115 NCT51SN055 GND GND HYST GND GND HYST Figure 1. Over and Under Temperature Alarm safe measure could be designed by using a second NCT52 with a higher temperature threshold to alert the user of an impending thermal shutdown, should the temperature continue to rise. (See Figure 2) The NCT52 can be used to control a DC fan. The fan turns on when the sensed temperature rises above the factory set threshold and remains on until the temperature falls below threshold minus the hysteresis selected. An additional fail http://onsemi.com 4 NCT51, NCT52 +5 V VCC 100 pF TEMPERATURE FAULT NCT52SN095 GND HEAT GND TOVER HYST µP FAN CONTROL HEAT VCC TOVER HYST 100 pF NCT52SN055 GND GND Figure 2. Fan Control Circuit with Over Temperature Alert TOVER + V TOVER Positive Tempco Reference NCT51 With 100 kΩ Pull–Up Negative Tempco Reference HYST Network HYST NCT51 TEMP COLD +25°C TTH HOT + TOVER V TOVER Positive Tempco Reference NCT52 Negative Tempco Reference HYST Network HYST NCT52 TEMP COLD Figure 3. Functional Block Diagrams http://onsemi.com 5 +25°C TTH HOT NCT51, NCT52 TYPICAL CHARACTERISTICS 40 60 35 SUPPLY CURRENT (µA) FREQUENCY 50 40 30 20 30 25 20 15 10 10 5 –3 –4 –2 –1 0 1 2 4 3 0 –60 –40 –20 5 20 40 60 80 100 120 140 TEMPERATURE (°C) Figure 4. Trip Threshold Accuracy Figure 5. Supply Current vs. Temperature 80 180 140 OUTPUT SINK RESISTANCE (Ω) VCC = 2.7 V 160 VCC = 4.0 V 120 100 VCC = 5.0 V 80 60 180 40 20 0 ACCURACY (°C) 0 20 40 60 80 100 120 VCC = 2.7 V VCC = 4.0 V 70 60 VCC = 5.0 V 50 40 30 20 10 0 140 0 10 20 30 40 50 60 70 80 TEMPERATURE (°C) TEMPERATURE (°C) Figure 6. NCT52 Output Source Resistance vs. Temperature Figure 7. Output Sink Resistance vs. Temperature 12 HYS = VCC 10 HYSTERESIS (°C) OUTPUT SOURCE RESISTANCE (Ω) 0 –5 NCT51/52 8 6 4 HYS = GND 2 NCT51/52 0 –45 –25 –5 15 35 55 75 95 TRIP TEMPERATURE (°C) Figure 8. Hysteresis vs. Trip Temperature http://onsemi.com 6 115 90 100 NCT51, NCT52 TYPICAL CHARACTERISTICS +100°C +15°C/div Mounted On 0.75 in2 of 2 oz. Copper +25°C 5 sec/div Figure 9. SOT–23 Thermal Step Response in Perfluorinated Fluid +100°C +12.5°C/div Mounted On 0.75 in2 of 2 oz. Copper +25°C 20 sec/div Figure 10. SOT–23 Thermal Step Response in Still Air http://onsemi.com 7 NCT51, NCT52 Component Taping Orientation for 5–Pin SOT–23A (EIAJ SC–74A) Devices USER DIRECTION OF FEED DEVICE MARKING PIN 1 Standard Reel Component Orientation TR Suffix Device (Mark Right Side Up) PIN 1 USER DIRECTION OF FEED DEVICE MARKING W = Width of Carrier Tape P = Pitch Reverse Reel Component Orientation RT Suffix Device (Mark Upside Down) Carrier Tape, Reel Size, and Number of Components Per Reel Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size SOT–23A 8 mm 4 mm 3000 7 inches http://onsemi.com 8 NCT51, NCT52 MARKING DIAGRAM 1 2 3 4 1 and 2 3 = Two Letter Part Number Codes = Year and Two–Month Period Code 4 = Lot ID Number ORDERING INFORMATION Device Package NCT51SN055T1 NCT51SN095T1 NCT51SN115T1 NCT52SN055T1 NCT52SN095T1 NCT52SN115T1 5 Pin SOT–23A SOT 23A 5–Pin Standard Temperature Threshold Output Stage 1 and 2 55°C 95°C 115°C Open Drain Open Drain Open Drain HB HF HH 55°C 95°C 115°C Push/Pull Push/Pull Push/Pull JB JF JH Marking http://onsemi.com 9 Shipping 3000 Units Tape and Reel NCT51, NCT52 Notes http://onsemi.com 10 NCT51, NCT52 PACKAGE DIMENSIONS SOT–23 SN SUFFIX CASE 1212–01 ISSUE O A B D 5 E 1 A2 0.05 S A1 4 2 L 3 E1 L1 B e e1 NOTES: 1. DIMENSIONS ARE IN MILLIMETERS. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M, 1994. 3. DATUM C IS A SEATING PLANE. C 5X 0.10 M C B S A S C http://onsemi.com 11 DIM A1 A2 B C D E E1 e e1 L L1 MILLIMETERS MIN MAX 0.00 0.10 1.00 1.30 0.30 0.50 0.10 0.25 2.80 3.00 2.50 3.10 1.50 1.80 0.95 BSC 1.90 BSC 0.20 --0.45 0.75 NCT51, NCT52 ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. 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