general description MAX6685/max6686 are dual-output temperature switches that 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 is controlled 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 threshold from +40? to +80? or +75? to +115? (5? increments) preset upper threshold: +120? or +125? open-drain, active-low output for upper temperature 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 dxn s2 3 3v to system shutdown n t low dxp v dd t h gh max6686 c s gnd cpu s1 dxn s2 3.3v to system shutdown to clock throttle control t low dxp v dd t h gh 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 c) pin-package MAX6685 au40l push-pull, active high +40 c to +80 c +120 c 8 max MAX6685au40h push-pull, active high +40 c to +80 c +125 c 8 max MAX6685au75l push-pull, active high +75 c to +115 c +120 c 8 max MAX6685au75h push-pull, active high +75 c to +115 c +125 c 8 max max6686 au40l open drain, active low +40 c to +80 c +120 c 8 max max6686au40h open drain, active low +40 c to +80 c +125 c 8 max max6686au75l open drain, active low +75 c to +115 c +120 c 8 max max6686au75h open drain, active low +75 c to +115 c +125 c 8 max pin configurations appear at end of data sheet. cpu temperature protection fan control multichip modules fpga temperature protection
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 absolute maximum ratings may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. voltages referenced to gnd v 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 max (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 a supply current during conversion 400 800 a 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 threshold accuracy ?
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 -25 120 140 160 180 200 100 -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 0 060 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 MAX6685u40h t high trip = +125c 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 MAX6685u40h s1 = s2 = v dd typical operating characteristics (v dd = 3.3v, c s = 2200pf, t a = +25 c, unless otherwise noted. see typical operating circuits.)
MAX6685/max6686 detailed description the MAX6685/max6686 dual-output remote-sensing junction 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 by integration 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 threshold temperature. 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 power is applied to the v dd pin. if this is done after the power is turned on, the lower trip threshold remains set to the point where s1 and s2 were when power was applied. applications information remote-diode selection the MAX6685/max6686 are optimized to measure the die 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 sources current 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 sinks current 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. 77s1 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. 88s2 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.
noise-filtering capacitors a quality ceramic capacitor must be connected across the 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 1 ? c error. MAX6685/max6686 dual-output remote-junction temperature switches _______________________________________________________________________________________ 5 n t low t high dxn s2 s1 gnd t high +120
MAX6685/max6686 dual-output remote-junction temperature switches 6 _______________________________________________________________________________________ top view t low t h gh dxn 1 2 8 7 s2 s1 gnd dxp v dd max 3 4 6 5 MAX6685 t low t high dxn 1 2 8 7 s2 s1 gnd dxp v dd max 3 4 6 5 max6686 pin configurations chip information transistor count: 7765 process: bicmos
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 0.950.75 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 60 0.13 0.18 max min millimeters - 1.10 0.05 0.15 dim
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