NCT22, NCT24 Low Cost Single Trip Point Temperature Sensor The NCT22 and NCT24 are programmable solid state temperature sensors designed to replace mechanical switches in sensing and control applications. Both devices integrate the temperature sensor with a voltage reference and all required detector circuitry. The desired temperature set point is set by the user with a single external resistor. Ambient temperature is sensed and compared to the programmed setpoint. The OUT and OUT outputs are driven to their active state when the measured temperature exceeds the programmed setpoint. The NCT22 has a power supply voltage range of 4.5 V to 18 V while the NCT24 operates over a power supply range of 2.7 V to 4.5 V. Both devices are useable over a temperature range of –40°C to +125°C. Both devices feature low supply current making them suitable for many portable applications. The devices are offered in surface mount packages. Features • Temperature Set Point Easily Programs with a Single External http://onsemi.com MARKING DIAGRAM 8 SOIC–8 D SUFFIX CASE 751 8 1 NCTxx ALYW 1 xx A L Y W = 22 or 24 = Assembly Location = Wafer Lot = Year = Work Week Resistor • Operates with 2.7 V Power Supply (NCT24) • Small SOIC Package • Cost Effective PIN CONNECTIONS N/C 1 Applications • • • • • OUT 2 Power Supply Over–Temperature Detection Consumer Electronics Fire/Heat Detection UPSs, Amplifiers, Motors CPU Thermal Management in PCs OUT 3 GND 8 N/C NCT22 NCT24 4 7 VDD 6 N/C 5 TSET (Top View) ORDERING INFORMATION See detailed ordering and shipping information in the package dimensions section on page 5 of this data sheet. +9 V + 9V Battery – Sounder Sensor RSET NCT22 7 NC VDD 8 5 TSET NC 1 6 4 NC CONTROL ASIC OUT 3 GND OUT 2 ALARM Figure 1. Heat Monitor for Smoke Detector Semiconductor Components Industries, LLC, 2000 December, 2000 – Rev. 0 1 Publication Order Number: NCT22/D NCT22, NCT24 ABSOLUTE MAXIMUM RATINGS* Rating Symbol Supply Voltage NCT22 NCT24 Value Unit VCC V 20 5.5 Input Voltage (Any Input) – GND –0.3 to VDD +0.3 V Operating Temperature Range – –40 to +125 °C Maximum Junction Temperature – +150 °C Tstg –65 to +150 °C – +300 °C Storage Temperature Range Lead Temperature (Soldering, 10 seconds) *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 (Over Operating Temperature Range, unless otherwise specified) Device Test Conditions Min Typ Max Unit Supply Voltage Range NCT22 NCT24 – 4.5 2.7 – – 18 4.5 V Supply Current NCT22 NCT24 5.0 V VDD 18 V – – 200 170 600 300 µA Characteristics VOH VOL VOH VOL Absolute Accuracy Trip Point Hysteresis NCT22 NCT22 NCT24 2.7 V VDD 4.5 V V 5.0 V VDD 18 V –40°C TA +125°C IOH = 250 µA IOH = 500 µA 0.9 x VDD 0.8 x VDD – – – – –40°C TA +85°C IOL = 500 µA IOL = 1.0 mA – – – – 0.15 x VDD 0.30 x VDD –40°C TA +125°C IOL = 1.0 mA – – 0.35 x VDD V V 2.7 V VDD 4.5 V –40°C TA +125°C IOH = 250 µA IOH = 500 µA 0.9 x VDD 0.8 x VDD – – – – –40°C TA +85°C IOL = 500 µA IOL = 1.0 mA – – – – 0.1 x VDD 0.2 x VDD –40°C TA +125°C IOL = 1.0 mA – – 0.25 x VDD NCT22 NCT24 TSET = Programmed Temperature TSET = Programmed Temperature T–5 T–5 T1 T+5 T+5 °C NCT22 NCT24 – – – – – °C NCT24 http://onsemi.com 2 V T1 2.0 2.0 NCT22, NCT24 Hysteresis DETAILED DESCRIPTION To prevent output “chattering’’ at the trip point temperature, the temperature detector in the NCT22/24 has 2°C of hysteresis (see Figure 3). The outputs are driven active when the temperature crosses the setpoint determined by the external resistor. As temperature declines below the setpoint, the hysteresis action will hold the outputs true until the temperature drops 2°C below the threshold. Trip Point Programming The NCT22 and NCT24 are single point temperature detectors ideal for use in a wide variety of applications. When the temperature of the device exceeds the programmed temperature trip point, TSET, the OUT and OUT outputs are driven into their active states. The desired trip point temperature is programmed with a single external resistor connected between the TSET input and VCC. The relationship between the resistor value and the trip point temperature is given by the equation below. TEMPERATURE RTRIP 0.5997 T2.1312 Where Rtrip Programming resistor value in Ohms T = Desired trip temperature in degrees Kelvin. SET POINT (SET POINT–2°C) OUT For example, to program the device to trip at 50°C, the programming resistor is: RTRIP 0.5997 ((50 273.15)2.1312) 133, 652 OUT 250 RESISTANCE (kΩ) Figure 3. NCT22/24 Hysteresis 200 APPLICATIONS Over–Temperature Shutdown 150 The NCT22 can be used to create a simple over–temperature shutdown circuit. In this circuit, temperature is sensed within the system enclosure (internal system ambient), or at the heatsink itself. When measured temperature exceeds a preset limit, a fault is indicated and the system shuts down. Figure 4 illustrates a simple over–temperature shutdown circuit using the NCT22 sensor. As shown, the NCT22 outputs are driven active when the heatsink temperature equals the trip point temperature set by RSET. When this happens, the crowbar circuit is activated, causing the supply output to fold back to zero. The NCT22 outputs remain active until the heatsink temperature falls a minimum of 2°C (built–in hysteresis) below the trip point temperature, at which time the device again allows normal supply operation. 100 50 –55 –35 –15 5 25 45 65 85 105 125 TEMPERATURE (°C) Figure 2. Programming Resistor Values vs. Temperature http://onsemi.com 3 NCT22, NCT24 VCC VOUT OUTPUT DEVICE POWER GOOD SIGNAL RSET NCT22 TSET CROWBAR CIRCUIT VDD OVERTEMP OUT GND OUT HEATSINK SURFACE Figure 4. NCT22 Power Supply Over–Temperature Shutdown Cooling and Heating Applications Figure 6 shows the NCT22 acting as a heater thermostat. Circuit operation is identical to that of the cooling fan application. The NCT22/24 can be used to control a DC fan as shown in Figure 5. The fan turns on when the sensed temperature rises above TSET and remains on until the temperature falls below TSET –2°C. +2.7 to 4.5 V +4.5 to 18.0 V +12 V RSET 5 6 TEMPERATURE 4 RSET NC VDD TSET NC NCT24 OUT NC GND 7 + – 1 DC FAN 8 5 3 6 N–CHANNEL LOGIC LEVEL MOSFET OUT 4 TEMPERATURE 1 +12 V TSET TSET –2°C HEATER NC VDD NC TSET NCT22 OUT NC 7 8 2 GND OUT N–CHANNEL LOGIC LEVEL MOSFET TSET TSET –2°C OUT OUT HEATER “ON” FAN “ON” Figure 5. NCT24 As a Fan Controller for Notebook PCs Figure 6. NCT22 As a Heater Thermostat http://onsemi.com 4 NCT22, NCT24 ORDERING INFORMATION Voltage Operation Package Ambient Temperature Shipping NCT22DR2 4.5 V to 18 V SOIC–8 –40°C to +125°C 2500 Units Tape and Reel NCT24DR2 2.7 V to 4.5 V SOIC–8 –40°C to +125°C 2500 Units Tape and Reel Device http://onsemi.com 5 NCT22, NCT24 Notes http://onsemi.com 6 NCT22, NCT24 PACKAGE DIMENSIONS SO–8 D SUFFIX CASE 751–07 ISSUE V –X– NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSION A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. A 8 5 0.25 (0.010) S B 1 M Y M 4 K –Y– G C N X 45 SEATING PLANE –Z– 0.10 (0.004) H M D 0.25 (0.010) M Z Y S X S http://onsemi.com 7 J DIM A B C D G H J K M N S MILLIMETERS MIN MAX 4.80 5.00 3.80 4.00 1.35 1.75 0.33 0.51 1.27 BSC 0.10 0.25 0.19 0.25 0.40 1.27 0 8 0.25 0.50 5.80 6.20 INCHES MIN MAX 0.189 0.197 0.150 0.157 0.053 0.069 0.013 0.020 0.050 BSC 0.004 0.010 0.007 0.010 0.016 0.050 0 8 0.010 0.020 0.228 0.244 NCT22, NCT24 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. 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