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? semiconductor components industries, llc, 2002 june, 2002 rev. 1 1 publication order number: nct51/d nct51, nct52 ultra small temperature switch with pin-selectable hysteresis the nct51 and nct52 are sot23 temperature switches that require no external components and the design is facilitated with factoryprogrammed temperature thresholds. a choice of factorytrimmed 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 m a 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 hottemperature 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 5pin sot23a packages, these parts are ideal for applications requiring high integration, small size, low power and low installed cost. features ? 5pin sot23a ? factoryprogrammed thresholds from +45 c to +115 c in 10 c increments ? pinselectable +2 c or +10 c hysteresis ? 0.5 c (typ) threshold accuracy over full temperature range ? no external components required ? 17 m a supply current typical applications ? thermal management in pcs and servers ? over temperature fail safe circuits ? simple fan controller ? temperature alarms ? projectors/printers ? notebook computers ? network boxes sot23a sn suffix case 1212 1 pin connections 2 3 4 5 see detailed ordering and shipping information in the package dimensions section on page 9 of this data sheet. ordering information see general marking information in the device marking section on page 9 of this data sheet. device marking information 5 1 2 4 3 t over (t over )* gnd v cc *for nct52 note: 5pin sot23a is equivalent to eiaj sc74a gnd hyst http://onsemi.com
nct51, nct52 http://onsemi.com 2 maximum ratings* rating symbol value unit supply voltage v cc 0.3 to +7.0 v tover (nct51) 0.3 to +7.0 v tover (nct52) 0.3 to (v cc +0.3) v all other pins 0.3 to (v cc +0.3) v input current (all pins) 20 ma output current (all pins) 20 ma operating temperature range 55 to +125 c storage temperature range t stg 65 to +165 c lead temperature (soldering, 10 seconds) +300 c power dissipation (t a = +70 c) (derate 7.1 mw/ c above +70 c) 571 mw *staticsensitive 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 f unctional operation of the device at these or any other conditions above those indicated in the operational sections of the specification s is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. electrical characteristics v cc = +2.7 v to +5.5 v, r pullup = 100 k w (nct51 only), c coupling = 100 pf from v cc to gnd, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c. characteristics test conditions symbol min typ max unit supply voltage range v cc 2.7 5.5 v supply current i cc 17 40 m a temperature threshold accuracy (note 1) +45 c to +65 c +75 c to +115 c d t th 4.0 6.0 0.5 0.5 4.0 6.0 c temperature threshold hysteresis hyst = gnd hyst = v cc t hyst 2.0 10 c hyst input threshold v ih 0.8 x v cc v hyst input threshold v il 0.2 x v cc v output voltage high i source = 500 m a, v cc 2.7 v (nct52 only) i source = 800 m a, v cc 4.5 v (nct52 only) v oh 0.8 x v cc v cc 1.5 v output voltage low i sink = 1.2 ma, v cc 2.7 v i sink = 3.2 ma, v cc 4.5 v v ol 0.3 0.4 v opendrain output leakage current v cc = 2.7 v, v tover = 5.5 v (nct51 only) 10 na 1. the nct51 and nct52 are available with internal, factoryprogrammed temperature trip thresholds from +45 c to +115 c in +10 c increments.
nct51, nct52 http://onsemi.com 3 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 v cc for +10 c hysteresis. 4 4 v cc supply input (+2.7 v to +5.5 v). recommend 100 pf or greater coupling capacitor from v cc to gnd. 5 tover opendrain, activelow output. tover goes low when the die temperature exceeds the factoryprogrammed temperature threshold. connect to a 100 k w pullup resistor. may be pulled up to a voltage higher than v cc . 5 tover push/pull activehigh output. tover goes high when the die temperature exceeds the factoryprogrammed temperature threshold. tunder opendrain, activelow output. tunder goes low when the die temperature goes below the factoryprogrammed temperature threshold. connect to a 100 k w pullup resistor. may be pulled up to a voltage higher than v cc . tunder push/pull activehigh output. tunder goes high when the die temperature is below the factoryprogrammed temperature threshold. typical operating circuit gnd nct52 gnd v cc v cc gnd hyst tover int m p 100 pf +2.7 v to +5.5 v detailed description the nct51 and nct52 integrate a temperature sensor with a factoryprogrammed 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. 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. hysteresis input to prevent the output from achattering'' 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 = v dd ) 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. table 1. factoryprogrammed threshold range part number threshold (t th ) range nct51 +45 c t th +115 c nct52 +45 c t th +115 c thermal considerations with a very low 17 m a 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 5pin sot23a 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 5pin sot23a.
nct51, nct52 http://onsemi.com 4 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 5pin sot23a package can be placed directly under the socketed microprocessor for improved thermal contact. 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 wireoring the outputs and using an external pull up resistor. (see figure 1) gnd nct51sn115 v cc gnd hyst 100 pf +5 v gnd v cc gnd hyst nct51sn055 temperature out of range r pullup 100 k 100 pf figure 1. over and under temperature alarm 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 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)
nct51, nct52 http://onsemi.com 5 heat heat gnd nct52sn095 hyst 100 pf +5 v gnd v cc gnd hyst nct52sn055 temperature fault m p 100 pf v cc gnd tover tover fan control figure 2. fan control circuit with over temperature alert nct51 nct52 hyst tover positive tempco reference - + negative tempco reference hyst network hyst tover positive tempco reference - + negative tempco reference hyst network nct51 nct52 figure 3. functional block diagrams nct51 nct52 v tover v tover cold +25 ct th hot temp with 100 k w pullup cold +25 ct th hot temp nct51 nct52
nct51, nct52 http://onsemi.com 6 typical characteristics 12 10 6 8 4 2 0 30 20 35 15 25 10 40 50 5 30 60 0 20 50 1 1 3 2 accuracy ( c) frequency 10 40 0 4 temperature ( c) figure 4. trip threshold accuracy figure 5. supply current vs. temperature supply current ( m a) 0 180 160 120 80 60 40 140 100 60 40 20 20 100 120 140 figure 6. nct52 output source resistance vs. temperature temperature ( c) figure 7. output sink resistance vs. temperature temperature ( c) output sink resistance ( w ) output source resistance ( w ) figure 8. hysteresis vs. trip temperature trip temperature ( c) hysteresis ( c) 3 45 35 15 5 25 55 75 95 60 20 40 0 20 60 40 80 04050 30 20 60 10 100 30 60 20 40 10 70 80 v cc = 2.7 v 45 2 5 0 100 120 140 80 180 v cc = 4.0 v v cc = 5.0 v v cc = 2.7 v v cc = 4.0 v v cc = 5.0 v 0 80 90 70 115 nct51/52 nct51/52 hys = gnd hys = v cc
nct51, nct52 http://onsemi.com 7 typical characteristics figure 9. sot23 thermal step response in perfluorinated fluid 5 sec/div 20 sec/div figure 10. sot23 thermal step response in still air mounted on 0.75 in 2 of 2 oz. copper +15 c/div mounted on 0.75 in 2 of 2 oz. copper +100 c +25 c +12.5 c/div +100 c +25 c
nct51, nct52 http://onsemi.com 8 w = width of carrier tape device marking device marking pin 1 user direction of feed component taping orientation for 5pin sot23a (eiaj sc74a) devices standard reel component orientation tr suffix device (mark right side up) sot23a package carrier width (w) pitch (p) part per full reel reel size 8 mm 4 mm 3000 7 inches carrier tape, reel size, and number of components per reel reverse reel component orientation rt suffix device (mark upside down) pin 1 user direction of feed p = pitch
nct51, nct52 http://onsemi.com 9 and = two letter part number codes = year and twomonth period code = lot id number marking diagram 12 3 4 12 3 4 ordering information device package standard temperature threshold output stage marking and 2 1 shipping NCT51SN055T1 55 c open drain hb nct51sn095t1 95 c open drain hf nct51sn115t1 5 pin sot 23a 115 c open drain hh 3000 units tape and reel nct52sn055t1 5pin sot23a 55 c push/pull jb 3000 units tape and reel nct52sn095t1 95 c push/pull jf nct52sn115t1 115 c push/pull jh
nct51, nct52 http://onsemi.com 10 notes
nct51, nct52 http://onsemi.com 11 package dimensions sot23 sn suffix case 121201 issue o dim min max millimeters a1 0.00 0.10 a2 1.00 1.30 b 0.30 0.50 c 0.10 0.25 d 2.80 3.00 e 2.50 3.10 e1 1.50 1.80 e 0.95 bsc e1 1.90 bsc l l1 0.45 0.75 notes: 1. dimensions are in millimeters. 2. interpret dimensions and tolerances per asme y14.5m, 1994. 3. datum c is a seating plane. a 1 5 23 4 d e1 b l1 e e e1 c m 0.10 c s b s a b 5x a2 a1 s 0.05 c l 0.20 ---
nct51, nct52 http://onsemi.com 12 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. nct51/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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