general description the max6687/max6688 comprise a remote-junctiontemperature switch and a local temperature switch in a single package. the remote-junction switch uses an external p-n junction (typically a diode-connected tran- sistor on the die of an external cpu, asic, or fpga) as a sensing element to measure the remote temperature. the remote-junction temperature switch has a factory- programmed trip temperature threshold of either +120? or +125?. the local temperature switch has a pin-programmable temperature threshold that is set by connecting pins s1 and s2 to ground, to v dd , or leav- ing them floating. hysteresis for both local and remotethresholds is 5?. the max6687/max6688 do not assert on transient (single-sample) faults or when power is first applied. the max6687 has two open-drain active-low outputs while the max6688 has two push-pull active-high out- puts. t remote asserts a logic signal when the remote temperature exceeds the factory-programmed +120?or +125? trip threshold. t local is asserted when the die temperature exceeds the pin-programmed thresh-old, which is controlled by pins s1 and s2. the local thresholds are available in two ranges in 5? incre- ments. the two ranges are +40? to +80? and +75? to +115?. the max6687/max6688 operate from a 3.0v to 5.5v power supply and are available in a space-saving 8-pin ?ax package. applications cpu temperature protection fpga temperature protection fan control temperature alarms features ? pin-programmable local temperature thresholdin 5? increments in two distinct ranges: +40? to +80? and +75? to +115? ? factory-programmed remote threshold: +120? (l suffix) or +125? (h suffix) ? open-drain active-low outputs (max6687) ? cmos push-pull, active-high outputs (max6688) ? ?.5? accuracy ? 2hz temperature sampling rate ? 215? average supply current ? 3.0v to 5.5v power-supply voltage ? 8-pin ?ax package max6687/max6688 local/remote temperature switches in a max package ________________________________________________________________ maxim integrated products 1 ordering information 19-2636; rev 2; 11/03 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. pin configurations/functional diagrams/selector guideappear at end of data sheet. part temp range pin-package max6687 au40l -40 c to +125 c 8 ?ax max6687au40h -40 c to +125 c 8 ?ax max6687au75l -40 c to +125 c 8 ?ax max6687au75h -40 c to +125 c 8 ?ax max6688 au40l -40 c to +125 c 8 ?ax max6688au40h -40 c to +125 c 8 ?ax max6688au75l -40 c to +125 c 8 ?ax max6688au75h -40 c to +125 c 8 ?ax dxp gnd s2 dxn v dd 3.3v s1 to systemshutdown c s 3.3v 12v n max6687 t remote t local dxp gnd s2 dxn v dd 3.3v s1 c s max6688 t remote t local to system shutdown p p typical operating circuit downloaded from: http:///
max6687/max6688 local/remote temperature switches in a max package 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics(v dd = 3v 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 local , t remote ............................................-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 5.5 v average supply current i dd 215 500 ? supply current duringconversion 400 800 ? power-on reset (por) threshold por v dd falling edge 1 1.5 2.0 v por threshold hysteresis 50 mv t a = +25 c, v dd = 3.3v -1.5 +1.5 t a = 0 c to +85 c, v dd = 3.3v -3.0 +3.0 remote-diode temperaturethreshold accuracy, rising temperature ? t th t a = -40 c to +125 c, v dd = 3.3v -5.0 +5.0 c temperature trip thresholds from +40 c to +105 c, v dd = 3.3v -3.0 +3.0 internal temperature thresholdaccuracy, rising temperature ? t th temperature trip thresholds +110 c and +115 c, v dd = 3.3v -3.5 +3.5 c temperature thresholdhysteresis t hyst 5.0 c temperature threshold supplysensitivity 0.6 c/v output voltage high v oh i source = 1ma, max6688 v dd - 0.2 v output voltage low v ol i sink = 1ma 0.2 v logic input low voltage(s1, s2) v il 0.4 v logic input high voltage(s1, s2) v ih 1.8 v input current (s1, s2) 10 ? open-drain output leakagecurrent v out = 5.5v, max6687 1 a downloaded from: http:///
max6687/max6688 local/remote temperature switches in a max package _______________________________________________________________________________________ 3 note 1: all parameters are tested at +25 c. temperature specifications over a range of -40 c to +125 c are guaranteed by design. electrical characteristics (continued)(v dd = 3v 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) parameter symbol condition min typ max units temperature conversion time 0.2 0.25 0.3 s temperature sample period 0.4 0.5 0.6 s high level 80 100 120 current sourcing for external diode low level 8 10 12 ? typical operating characteristics (v dd = 3.3v, c s = 2200pf, t a = +25 c, unless otherwise noted.) average supply current vs. ambient temperature max6687/88 toc01 ambient temperature ( c) average supply current ( a) 100 75 50 25 0 -25 140 180 220 260 300100 -50 125 average supply current vs. supply voltage max6687/88 toc02 supply voltage (v) average supply current ( a) 5.0 4.5 4.0 3.5 140 180 220 260 300100 3.0 5.5 t a = +100 c t a = -40 c t a = +25 c temperature trip threshold error vs. c s capacitance max6687/88 toc03 c s capacitance (nf) temperature trip threshold error ( c) 10 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0 1 100 max6688u40hs1 = s2 = float remote temperature trip threshold error vs. ambient temperature max6687/88 toc04 ambient temperature ( c) upper trip threshold error ( c) 75 50 25 0 -25 -4 -3 -2 -1 0 1 -5 -50 100 max6688u40ht remote trip = +125 c downloaded from: http:///
max6687/max6688 detailed description the max6687/max6688 sense the temperatures ofboth a remote p-n junction and their own die. the external p-n junction is typically a base-emitter junction of a substrate pnp on a microprocessor, fpga, or asic die (see the typical operating circuit ). the remote temperature switch has a factory-pro-grammed trip temperature of either +120 c or +125 c and is intended to be used for system shutdown whenthe die temperature of a remote ic, such as a micro- processor, fpga, or asic exceeds the factory-pro- grammed thresholds. the local temperature switch has a pin-programmable threshold temperature (table 1). this temperature switch may be used for such functions as system shut- down or for turning on a cooling fan when board tem- perature exceeds the temperature limit. two temperature ranges are available for the local trip threshold: +40 c to +80 c and +75 c to +115 c. s1 and s2 pins must be set to the desired trip temperaturebefore power is applied to the v dd pin. if s1 and s2 settings are changed after the power is turned on, thelocal trip threshold remains set to the point where s1 and s2 were when power was applied. since the max6687/max6688 are often used for sys- tem shutdown, they are designed so that the outputs do not change on transient faults or when power is first applied. this eliminates the possibility that the ic could erroneously shut a system down. the max6687/max6688 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. local/remote temperature switches in a max package 4 _______________________________________________________________________________________ pin description pin max6687 max6688 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. 44d x n 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 at the pin. 5 t remote open-drain active-low output. t remote goes low when the temperature exceeds the factory- programmed temperature threshold, either +120 c or +125 c. connect a pullup resistor (typically 10k ) between t remote and a positive power supply up to 5.5v. 5t remote cmos push-pull, active-high output. t remote goes high when the temperature exceeds the factory-programmed temperature threshold, either +120 c or +125 c. 6 t local open-drain active-low output. t local goes low when the temperature exceeds the pin- programmable temperature threshold set by s1 and s2. connect a pullup resistor (typically10k ) between t local and a positive power supply up to 5.5v. 6t local cmos push-pull, active-high output. t local goes high when the temperature exceeds the pin-programmable temperature threshold set by s1 and s2. 77s 1 threshold select input. used in conjunction with s2 to set the local threshold temperature(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 local threshold temperature(table 1). it can be connected to v dd , gnd, or left floating. downloaded from: http:///
applications information remote-diode selection the max6687/max6688 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 ground- ed. connect the base of the pnp to dxn and the emit- ter 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 forward current gain indicate the manufacturer has good process controls and that the devices have consistent v be characteristics. always use a transistor for the sensing junction; diodesdo not work. the max6687/max6688 are optimized for use with thermal-sensing transistors with an ideality factor of 1.008. different ideality factors cause predictable, usu- ally small deviations in trip temperature thresholds. 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% increase from the recommended capacitor value can cause up to ? c error. sensing circuit board and ambient temperature temperature switches like the max6687/max6688 thatsense their own die (local) temperatures must be mounted on or close to the object whose temperature they are intended to measure. the max6687/max6688 can accurately measure the temperature of a circuit board to which they are soldered because the package leads provide a good thermal path between the circuit board and their own die. if the max6687/max6688 are intended to be triggered by the temperature of a heat- generating component on the circuit board, they should be mounted as close as possible to that component and should share supply and ground traces (if they are not noisy) with that component where possible. the thermal path between the plastic package and the die is not as good as the path through the package leads, so the max6687/max6688 are less sensitive to the sur- rounding air temperature than they are to the tempera- ture of their package leads, but they can be successfully used to respond to the ambient tempera- ture if the circuit board is designed to track the ambient temperature. chip information transistor count: 7765process: bicmos max6687/max6688 local/remote temperature switches in a max package _______________________________________________________________________________________ 5 max6687aua40l/max6687aua40h/ max6688aua40l/max6688aua40h max6687aua75l/max6687aua75h/ max6688aua75l/max6688aua75h s1 s2 localtemperature trip threshold ( c) local 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. local temperature trip threshold selection manufacturer model no. central semiconductor (usa) cmpt3904 rohm semiconductor (japan) sst3904 samsung (korea) kst3904-tf siemens (germany) smbt3904 table 2. sensor transistor manufacturers downloaded from: http:///
max6687/max6688 local/remote temperature switches in a max package 6 _______________________________________________________________________________________ dxn 12 8 7 s2 s1 gnd dxp v dd max top view 3 4 6 5 max6687 t local t remote dxn 12 8 7 s2 s1 gnd dxp v dd max 3 4 6 5 max6688 t local t remote pin configurations selector guide part outputs remote trip threshold ( c) local trip threshold range ( c) MAX6687AU40L open drain, active low +120 +40 to +80 max6687au40h open drain, active low +125 +40 to +80 max6687au75l open drain, active low +120 +75 to +115 max6687au75h open drain, active low +125 +75 to +115 max6688au40l push pull, active high +120 +40 to +80 max6688au40h push pull, active high +125 +40 to +80 max6688au75l push pull, active high +120 +75 to +115 max6688au75h push pull, active high +125 +75 to +115 remote temperature converter t remote +120 c or +125 c t remote +40 c or +115 c s1 dxp dxn s2 v dd gnd n n local temperature converter max6687 t remote t local figure 1a. max6687 functional block diagram remote temperature converter t remote +120 c or +125 c t remote +40 c or +115 c s1 dxp dxn s2 v dd gnd local temperature converter max6688 t remote t local digital driver digital driver figure 1b. max6688 functional block diagram functional block diagrams downloaded from: http:///
max6687/max6688 local/remote temperature switches in a max package 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:///
|
