general description max6685/max6686 are dual-output temperature switchesthat use an external diode-connected transistor as a sens- ing element. these devices have two logic outputs (t high and t low ). t high asserts a logic signal when the remote temperature crosses the factory-programmed, +120?, or+125? upper trip threshold. t low is asserted when the remote temperature exceeds the lower threshold, which iscontrolled by pins s1 and s2. the lower thresholds are available in two ranges in 5? increments. the two ranges are +40? to +80? and +75? to +115?. hysteresis for both outputs to be deasserted is typically 5?. t high is an open-drain, active-low output for both the max6685 and the max6686. t low is a cmos push-pull, active-high output for the max6685 and is an open-drain,active-low output for the max6686. they are available in a space-saving 8-pin ?ax package. applications features ? pin-programmed lower temperature thresholdfrom +40? to +80? or +75? to +115? (5? increments) ? preset upper threshold: +120? or +125? ? open-drain, active-low output for uppertemperature alarm ? cmos push-pull, active-high or open-drain,active-low output for lower temperature alarm ? 1.5? accuracy ? 3.0v to 5.5v, 200? supply ? 8-pin ?ax package max6685/max6686 dual-output remote-junction temperature switches ________________________________________________________________ maxim integrated products 1 ordering information max6685 c s 12v gnd cpu s1 dxns2 3.3v to system shutdown n t low dxp v dd t high max6686 c s gnd cpu s1 dxns2 3.3v to system shutdown to clock throttle control t low dxp v dd t high typical operating circuits 19-2459; rev 2; 4/03 for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. part t low output t low trip range (0 c) t high trip threshold (0 ?) pin-package max6685 au40l push-pull, active high +40 c to +80 c +120 c 8 ?ax MAX6685AU40H push-pull, active high +40 c to +80 c +125 c 8 ?ax max6685au75l push-pull, active high +75 c to +115 c +120 c 8 ?ax max6685au75h push-pull, active high +75 c to +115 c +125 c 8 ?ax max6686 au40l open drain, active low +40 c to +80 c +120 c 8 ?ax max6686au40h open drain, active low +40 c to +80 c +125 c 8 ?ax max6686au75l open drain, active low +75 c to +115 c +120 c 8 ?ax max6686au75h open drain, active low +75 c to +115 c +125 c 8 ?ax pin configurations appear at end of data sheet. cpu temperatureprotection fan control multichip modulesfpga temperature protection downloaded from: http:///
max6685/max6686 dual-output remote-junction temperature switches 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics(v dd = 3.0v to 5.5v, t a = -40 c to +125 c, unless otherwise noted. typical values are at v dd = 3.3v and t a = +25 c.) (note 1) stresses beyond those listed under ?bsolute 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 beyond 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. voltages referenced to gndv dd, t low , t high .....................................................-0.3v to +6v dxn .......................................................................-0.3v to +0.8v all other pins..............................................-0.3v to (v dd + 0.3v) input current .........................................................................5ma output current ....................................................................20ma continuous power dissipation (t a = +70 c) 8-pin ?ax (derate 4.1mw/ c above +70 c) .............330mw operating temperature range .........................-40 c to +125 c junction temperature ......................................................+150 c storage temperature range .............................-65 c to +165 c lead temperature (soldering, 10s) .................................+300 c parameter symbol condition min typ max units power-supply range v dd 3.0 5.5 v average supply current i dd 200 500 ? supply current duringconversion 400 800 ? power-on reset threshold por v dd falling edge 1.0 1.5 2.0 v por threshold hysteresis 50 mv v dd = 3.3v, t a = +25 c, t rj = 0 c to +125 c (note 2) -1.5 +1.5 temperature thresholdaccuracy ? t th t a = 0 c to +100 c, t rj = 0 c to +125 c 2.0 ? temperature thresholdhysteresis t hyst 5.0 ? supply sensitivity of temperaturethreshold t a = +25 c, t rj = 0 c to +125 c, v dd = 3.0v to 5.5v 0.6 c/v output voltage high v oh i source = 1ma, max6685 t low only v dd - 0.2 v output voltage low v ol i sink = 1ma 0.2 v logic-low input voltage v il s1, s2 0.4 v logic-high input voltage v ih s1, s2 1.8 v input current s1, s2 10 ? open-drain output leakagecurrent v out = 5.5v, t low and t high 1 a conversion time 0.09 0.11 0.13 s sample period 0.35 0.45 0.55 s high level 80 100 120 current sourcing for external diode low level 8 10 12 ? note 1: all parameters are tested at +25 c. temperature specifications over a range of -40 c to +125 c are guaranteed by design. note 2: t rj is the temperature of the remote-sensing diode junction. downloaded from: http:///
max6685/max6686 dual-output remote-junction temperature switches _______________________________________________________________________________________ 3 average supply current vs. ambient temperature max6685 toc01 ambient temperature ( c) average supply current ( a) 100 75 50 25 0 -25 120 140 160 180 200100 -50 125 average supply current vs. supply voltage max6685 toc02 supply voltage (v) average supply current ( a) 5.0 4.5 4.0 3.5 50 100 150 200 250 0 3.0 5.5 temperature trip threshold error vs. c s capacitance max6685 toc03 c s capacitance (nf) temperature trip threshold error ( c) 50 40 30 20 10 2 4 6 8 10 0 06 0 max6685u40h s1 = s2 = gnd upper temperature trip threshold error vs. ambient temperature max6685 toc04 ambient temperature ( c) upper trip threshold error ( c) 100 75 25 50 0 -25 -1.6 -1.2 -0.8 -0.4 0 0.4 0.8 1.2 1.6 2.0 -2.0 -50 125 max6685u40ht high trip = +125 c lower temperature trip threshold error vs. ambient temperature max6685 toc05 ambient temperature ( c) lower trip threshold error ( c) 100 75 25 50 0 -25 -1.6 -1.2 -0.8 -0.4 0 0.4 0.8 1.2 1.6 2.0 -2.0 -50 125 max6685u40hs1 = s2 = v dd typical operating characteristics (v dd = 3.3v, c s = 2200pf, t a = +25 c, unless otherwise noted. see typical operating circuits .) downloaded from: http:///
max6685/max6686 detailed description the max6685/max6686 dual-output remote-sensingjunction temperature switches incorporate a precision remote-junction temperature sensor and two compara- tors. these devices use an external p-n junction as the temperature-sensing element (see typical operating circuits ). the max6685/max6686 provide noise immunity byintegration and oversampling of the diode voltage, but good design practice includes routing the dxp and dxn lines away from noise sources, such as high- speed digital lines, switching regulators, inductors, and transformers. the dxp and dxn traces should be paired together and surrounded by a ground plane whenever possible. the 5 c hysteresis keeps the outputs from chattering when the measured temperature is close to the thresholdtemperature. the max6685/max6686 are available with preset upper temperature thresholds of +120 c or +125 c. the lower temperature thresholds are pin pro- grammable in 5 c increments (table 1). two tempera- ture ranges are available for the lower trip threshold:+40 c to +80 c and +75 c to +115 c. s1 and s2 pins must be set to the desired trip temperature before poweris applied to the v dd pin. if this is done after the power is turned on, the lower trip threshold remains set to thepoint where s1 and s2 were when power was applied. applications information remote-diode selection the max6685/max6686 are optimized to measure thedie temperature of cpus and other ics that have on-chip temperature-sensing diodes. these on-chip diodes are substrate pnps with their collectors grounded. connect the base of the pnp to dxn and the emitter to dxp. when using a discrete, diode-connected npn or pnp as a sensing diode, use a good-quality small-signal device. examples are listed in table 2. tight specifications for for- ward current gain indicate the manufacturer has good process controls and that the devices have consistent v be characteristics. always use a transistor for the sens- ing junction; diodes do not work. dual-output remote-junction temperature switches 4 _______________________________________________________________________________________ pin description pin max6685 max6686 name function 11v dd power-supply input. bypass to gnd with a 0.1? capacitor. 2 2 gnd ground 3 3 dxp this pin connects to the positive (anode) terminal of the external p-n sense junction. it sourcescurrent into the external junction. a 2200pf capacitor should be connected across dxp and dxn. 4 4 dxn this pin connects to the negative (cathode) terminal of the external p-n sense junction. it sinkscurrent from the external junction. a 2200pf capacitor should be connected across dxp and dxn. dxn must be connected to the gnd pin with the shortest possible connection. 55t high open-drain, active-low output. t high goes low when the temperature exceeds the factory- programmed upper temperature threshold, either +120? or +125?. connect a pullup resistor (typically 10k ) between t high and a positive supply up to 5.5v. 6 t low cmos push-pull, active-high output. t low goes high when the temperature exceeds the pin- programmed lower temperature threshold. ?t low open-drain, active-low output. t low goes low when the temperature exceeds the pin- programmed lower temperature threshold. connect a pullup resistor (typically 10k ) between t low and a positive supply up to 5.5v. 77s 1 threshold select input. used in conjunction with s2 to set the lower threshold for t low (table 1). it can be connected to v dd , gnd, or left floating. 88s 2 threshold select input. used in conjunction with s1 to set the lower threshold for t low (table 1). it can be connected to v dd , gnd, or left floating. downloaded from: http:///
noise-filtering capacitors a quality ceramic capacitor must be connected acrossthe dxp/dxn inputs to maintain temperature threshold accuracy by filtering out noise. the capacitor should be located physically close to the dxp/dxn pins and should typically have a value of 2200pf. larger capaci- tor values can cause temperature measurement errors. a 50% variation from the recommended capacitor value can cause up to ? c error. max6685/max6686 dual-output remote-junction temperature switches _______________________________________________________________________________________ 5 n t low t high dxn s2 s1 gnd t high +120 c or +125 c remote temperature converter t low +40 c to +115 c dxp v dd max6685 digital driver figure 1. max6685 functional diagram nn t low t high dxn s2 s1 gnd t high +120 c or +125 c remote temperature converter t low +40 c to +115 c dxp v dd max6686 figure 2. max6686 functional diagram max6685aua40l max6685aua40h max6686aua40l max6686aua40h max6685aua75l max6685aua75h max6686aua75l max6686aua75h s1 s2 lower temperature trip threshold ( c) lower temperature trip threshold ( c) gnd gnd +40 +75 gnd float +45 +80 gnd v dd +50 +85 float gnd +55 +90 float float +60 +95 float v dd +65 +100 v dd gnd +70 +105 v dd float +75 +110 v dd v dd +80 +115 table 1. lower temperature trip threshold selection manufacturer model no. central semiconductor (usa) cmpt3904 on semiconductor (usa) 2n3904, 2n3906 rohm semiconductor (japan) sst3904 samsung (korea) kst3904-tf siemens (germany) smbt3904 table 2. sensor transistor manufacturers note: discrete transistors must be diode connected (base shorted to collector). downloaded from: http:///
max6685/max6686 dual-output remote-junction temperature switches 6 _______________________________________________________________________________________ top view t low t high dxn 12 8 7 s2 s1 gnd dxp v dd max 3 4 6 5 max6685 t low t high dxn 12 8 7 s2 s1 gnd dxp v dd max 3 4 6 5 max6686 pin configurations chip information transistor count: 7765process: bicmos downloaded from: http:///
max6685/max6686 dual-output remote-junction temperature switches maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 _____________________ 7 2003 maxim integrated products printed usa is a registered trademark of maxim integrated products. package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline information, go to www.maxim-ic.com/packages .) 8lumaxd.eps package outline, 8l umax/usop 1 1 21-0036 j rev. document control no. approval proprietary information title: max 0.043 0.006 0.014 0.120 0.120 0.198 0.026 0.007 0.037 0.0207 bsc 0.0256 bsc a2 a1 c e b a l front view side view e h 0.60.1 0.60.1 ? 0.500.1 1 top view d 8 a2 0.030 bottom view 1 6 s b l h e d e c 0 0.010 0.116 0.116 0.188 0.016 0.005 8 4x s inches - a1 a min 0.002 0.95 0.75 0.5250 bsc 0.25 0.36 2.95 3.05 2.95 3.05 4.78 0.41 0.65 bsc 5.03 0.66 6 0 0.13 0.18 max min millimeters - 1.10 0.05 0.15 dim downloaded from: http:///
|
