? semiconductor components industries, llc, 2002 june, 2002 rev. 1 1 publication order number: nct22/d 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 resistor ? operates with 2.7 v power supply (nct24) ? small soic package ? cost effective applications ? power supply overtemperature detection ? consumer electronics ? fire/heat detection ? upss, amplifiers, motors ? cpu thermal management in pcs figure 1. heat monitor for smoke detector nct22 control asic nc t set nc gnd v dd nc out out alarm + 1 5 6 4 7 8 3 sounder +9 v r set 9 v battery sensor 2 soic8 d suffix case 751 pin connections see detailed ordering and shipping information in the package dimensions section on page 5 of this data sheet. ordering information 1 8 8 7 6 5 1 2 3 4 n/c n/c (top view) out out gnd v dd n/c t set nct22 nct24 nctxx alyw xx = 22 or 24 a = assembly location l = wafer lot y = year w = work week marking diagram 1 8 http://onsemi.com
nct22, nct24 http://onsemi.com 2 maximum ratings* rating symbol value unit supply voltage nct22 nct24 v cc 20 5.5 v input voltage (any input) gnd 0.3 to v dd +0.3 v operating temperature range 40 to +125 c maximum junction temperature +150 c storage temperature range t stg 65 to +150 c lead temperature (soldering, 10 seconds) +300 c *stresses above those listed under aabsolute maximum ratings'' may cause permanent damage to the device. these are stress ratin gs only and functional operation of the device at these or any other conditions above those indicated in the operational sections of th e 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) characteristics 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 v dd 18 v 2.7 v v dd 4.5 v 200 170 600 300 m a v oh nct22 5.0 v v dd 18 v 40 c t a +125 c i oh = 250 m a i oh = 500 m a 0.9 x v dd 0.8 x v dd v v ol nct22 40 c t a +85 c i ol = 500 m a i ol = 1.0 ma 40 c t a +125 c i ol = 1.0 ma 0.15 x v dd 0.30 x v dd 0.35 x v dd v v oh nct24 2.7 v v dd 4.5 v 40 c t a +125 c i oh = 250 m a i oh = 500 m a 0.9 x v dd 0.8 x v dd v v ol nct24 40 c t a +85 c i ol = 500 m a i ol = 1.0 ma 40 c t a +125 c i ol = 1.0 ma 0.1 x v dd 0.2 x v dd 0.25 x v dd v absolute accuracy nct22 nct24 t set = programmed temperature t set = programmed temperature t5 t5 t 1 t 1 t+5 t+5 c trip point hysteresis nct22 nct24 2.0 2.0 c
nct22, nct24 http://onsemi.com 3 detailed description 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, t set , 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 t set input and v cc . the relationship between the resistor value and the trip point temperature is given by the equation below. r trip 0.5997 t 2.1312 where rtrip programming resistor value in ohms t = desired trip temperature in degrees kelvin. for example, to program the device to trip at 50 c, the programming resistor is: r trip 0.5997 ((50 273.15) 2.1312 ) 133, 652 figure 2. programming resistor values vs. temperature 55 150 25 200 45 5 15 65 temperature ( c) resistance (k w ) 100 50 35 250 125 85 105 hysteresis to prevent output achattering'' 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. figure 3. nct22/24 hysteresis set point temperature out out (set point2 c) applications overtemperature shutdown the nct22 can be used to create a simple overtemperature 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 overtemperature 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 r set . 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 (builtin hysteresis) below the trip point temperature, at which time the device again allows normal supply operation.
nct22, nct24 http://onsemi.com 4 figure 4. nct22 power supply overtemperature shutdown output device v cc r set nct22 power good signal t set gnd v dd out out overtemp v out crowbar circuit heatsink surface cooling and heating applications 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 t set and remains on until the temperature falls below t set 2 c. figure 6 shows the nct22 acting as a heater thermostat. circuit operation is identical to that of the cooling fan application. figure 5. nct24 as a fan controller for notebook pcs +2.7 to 4.5 v r set nct24 dc fan t set gnd v dd out out nchannel logic level mosfet nc nc nc 1 5 6 4 7 8 3 + +12 v temperature t set t set 2 c out fan aono figure 6. nct22 as a heater thermostat +4.5 to 18.0 v r set nct22 heater t set gnd v dd out out nchannel logic level mosfet nc nc nc 1 5 6 4 7 8 2 +12 v temperature t set t set 2 c out heater aono
nct22, nct24 http://onsemi.com 5 ordering information device voltage operation package ambient temperature shipping nct22dr2 4.5 v to 18 v soic8 40 c to +125 c 2500 units tape and reel NCT24DR2 2.7 v to 4.5 v soic8 40 c to +125 c 2500 units tape and reel
nct22, nct24 http://onsemi.com 6 notes
nct22, nct24 http://onsemi.com 7 package dimensions so8 d suffix case 75107 issue v seating plane 1 4 5 8 n j x 45 k 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 b s d h c 0.10 (0.004) x y g m y m 0.25 (0.010) z y m 0.25 (0.010) z s x s m dim a min max min max inches 4.80 5.00 0.189 0.197 millimeters b 3.80 4.00 0.150 0.157 c 1.35 1.75 0.053 0.069 d 0.33 0.51 0.013 0.020 g 1.27 bsc 0.050 bsc h 0.10 0.25 0.004 0.010 j 0.19 0.25 0.007 0.010 k 0.40 1.27 0.016 0.050 m 0 8 0 8 n 0.25 0.50 0.010 0.020 s 5.80 6.20 0.228 0.244
nct22, nct24 http://onsemi.com 8 on semiconductor and are registered trademarks of semiconductor components industries, llc (scillc). scillc reserves the right to mak e 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 s pecifically disclaims any and all liability, including without limitation special, consequential or incidental damages. atypicalo 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 atypicalso 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 sit uation where personal injury or death may occur. should buyer purchase or use scillc products for any such unintended or unauthorized application, buyer shall indem nify and hold scillc and its of ficers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and re asonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized u se, even if such claim alleges that scillc was negligent regarding the design or manufacture of the part. scillc is an equal opportunity/affirmative action employ er. publication ordering information japan : on semiconductor, japan customer focus center 4321 nishigotanda, shinagawaku, tokyo, japan 1410031 phone : 81357402700 email : r14525@onsemi.com on semiconductor website : http://onsemi.com for additional information, please contact your local sales representative. nct22/d literature fulfillment : literature distribution center for on semiconductor p.o. box 5163, denver, colorado 80217 usa phone : 3036752175 or 8003443860 toll free usa/canada fax : 3036752176 or 8003443867 toll free usa/canada email : onlit@hibbertco.com n. american technical support : 8002829855 toll free usa/canada
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