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general description the max6693 precision multichannel temperature sen-sor monitors its own temperature and the temperatures of up to six external diode-connected transistors. all temperature channels have programmable alert thresh- olds. channels 1, 4, 5, and 6 also have programmable overtemperature thresholds. when the measured tem- perature of a channel exceeds the respective thresh- old, a status bit is set in one of the status registers. two open-drain outputs, overt and alert , assert corre- sponding to these bits in the status register.the 2-wire serial interface supports the standard system management bus (smbus) protocols: write byte, read byte, send byte, and receive byte for reading the tem- perature data and programming the alarm thresholds. the max6693 is specified for an operating temperature range of -40? to +125? and is available in a 20-pin tssop package. applications desktop computers notebook computers workstations servers features ? six thermal-diode inputs ? beta compensation (channel 1) ? local temperature sensor ? 1.5? remote temperature accuracy (+60? to+100?) ? temperature monitoring begins at por for fail-safe system protection ? alert and overt outputs for interrupts, throttling, and shutdown ? stby input for hardware standby mode ? small, 20-pin tssop package ? 2-wire smbus interface max6693 7-channel precision temperature monitor with beta compensation ________________________________________________________________ maxim integrated products 1 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. 2019 18 17 16 15 14 13 12 3 4 5 6 7 8 gnd smbclk smbdata dxn2 dxp2 dxn1 dxp1 v cc n.c. dxn4 dxp4 dxn3 dxp3 1211 9 10 dxp6 dxn6 dxn5 dxp5 max6693 alert overt stby 100pf 100pf 100pf 100pf 100pf cpu 100pf gpu 0.1 f to systemshutdown interruptto p data clk 4.7k each +3.3v typical application circuit 19-4096; rev 0; 5/08 smbus is a trademark of intel corp. pin configuration appears at end of data sheet. ordering information part temp range pin-package MAX6693UP9A+ -40? to +125? 20 tssop + denotes a lead-free package. note: slave address is 1001 101. downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation 2 _______________________________________________________________________________________ absolute maximum ratings 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. v cc , smbclk, smbdata, alert , overt , stby to gnd ....................................................-0.3v to +6.0v dxp_ to gnd..............................................-0.3v to (v cc + 0.3v) dxn_ to gnd ........................................................-0.3v to +0.8v smbdata, alert , overt current....................-1ma to +50ma dxn_ current......................................................................?ma continuous power dissipation (t a = +70?) 20-pin tssop (derate 13.6mw/? above +70?) .............................1084mw junction-to-case thermal resistance ( jc ) (note 1) 20-pin tssop...............................................................20?/w junction-to-ambient thermal resistance ( ja ) (note 1) 20-pin tssop............................................................73.8?/w esd protection (all pins, human body model) ....................?kv operating temperature range .........................-40? to +125? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? electrical characteristics(v cc = +3.0v to +3.6v, v stby = v cc , t a = -40? to +125?, unless otherwise noted. typical values are at v cc = +3.3v and t a = +25?.) (note 2) parameter symbol conditions min typ max units supply voltage v cc 3.0 3.6 v software standby supply current i ss smbus static 3 10 a operating current i cc during conversion (note 3) 500 2000 ? channel 1 only 11 temperature resolution other diode channels 8 bits t a = t rj = +60? to +100? -1.5 +1.5 3 temperature accuracy (remote channel 1) v cc = 3.3v, ?= 0.5 t a = t rj = 0? to +125? -2.375 +2.375 ? t a = t rj = +60? to +100? -2 +2 3 temperature accuracy (remote channels 2?) v cc = 3.3v t a = t rj = 0? to +125? -2.5 +2.5 ? t a = +60? to +100? -2 +2 3 temperature accuracy (local) v cc = 3.3v t a = 0? to +125? -2.5 +2.5 ? t a = t rj = +60? to +100? -3 +3 6 temperature accuracy (remote channel 1) v cc = 3.3v, ?= 0.5 t a = t rj = 0? to +125? -4 +4 ? t a = t rj = +60? to +100? -3 +3 6 temperature accuracy (remote channels 2?) v cc = 3.3v t a = t rj = 0? to +125? -3.5 +3.5 ? t a = +60? to +100? -2.5 +2.5 6 temperature accuracy (local) v cc = 3.3v t a = 0? to +125? -3 +3 ? supply sensitivity of temperatureaccuracy 0.2 o c/v remote channel 1 conversiontime t conv1 190 250 312 ms remote channels 2?conversion time t conv_ 95 125 156 ms note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four-layer board. for detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation _______________________________________________________________________________________ 3 electrical characteristics (continued)(v cc = +3.0v to +3.6v, v stby = v cc , t a = -40? to +125?, unless otherwise noted. typical values are at v cc = +3.3v and t a = +25?.) (note 2) parameter symbol conditions min typ max units high level, channel 1 500 low level, channel 1 20 high level, channels 2? 80 100 120 remote-diode source current i rj low level, channels 2? 8 10 12 ? undervoltage-lockout threshold uvlo falling edge of v cc disables adc 2.30 2.80 2.95 v undervoltage-lockout hysteresis 90 mv power-on reset (por) threshold v cc falling edge 1.20 2 2.25 v por threshold hysteresis 90 mv alert , overt i sink = 1ma 0.3 output low voltage v ol i sink = 6ma 0.5 v output leakage current 1 a smbus interface (smbclk, smbdata), stby logic-input low voltage v il 0.8 v logic-input high voltage v ih v cc = 3.0v 2.2 v input leakage current -1 +1 ? output low voltage v ol i sink = 6ma 0.3 v input capacitance c in 5p f smbus-compatible timing (figures 3 and 4) (note 4) serial-clock frequency f smbclk (note 5) 400 khz f smbclk = 100khz 4.7 bus free time between stopand start condition t buf f smbclk = 400khz 1.6 ? f smbclk = 100khz 4.7 start condition setup time f smbclk = 400khz 0.6 ? 90% of smbclk to 90% of smbdata,f smbclk = 100khz 0.6 repeat start condition setuptime t su:sta 90% of smbclk to 90% of smbdata,f smbclk = 400khz 0.6 ? start condition hold time t hd:sta 10% of smbdata to 90% of smbclk 0.6 ? 90% of smbclk to 90% of smbdata,f smbclk = 100khz 4 stop condition setup time t su:sto 90% of smbclk to 90% of smbdata,f smbclk = 400khz 0.6 ? downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation 4 _______________________________________________________________________________________ note 2: all parameters are tested at t a = +85?. specifications over temperature are guaranteed by design. note 3: beta = 0.5 for channel 1 remote transistor. note 4: timing specifications are guaranteed by design. note 5: the serial interface resets when smbclk is low for more than t timeout . note 6: a transition must internally provide at least a hold time to bridge the undefined region (300ns max) of smbclk? falling edge. electrical characteristics (continued)(v cc = +3.0v to +3.6v, v stby = v cc , t a = -40? to +125?, unless otherwise noted. typical values are at v cc = +3.3v and t a = +25?.) (note 2) parameter symbol conditions min typ max units 10% to 10%, f smbclk = 100khz 1.3 clock-low period t low 10% to 10%, f smbclk = 400khz 1.3 ? clock-high period t high 90% to 90% 0.6 s f smbclk = 100khz 300 data hold time t hd:dat f smbclk = 400khz (note 6) 900 ns f smbclk = 100khz 250 data setup time t su:dat f smbclk = 400khz 100 ns f smbclk = 100khz 1 receive smbclk/smbdatarise time t r f smbclk = 400khz 0.3 ? receive smbclk/smbdata falltime t f 300 ns pulse width of spike suppressed t sp 05 0 n s smbus timeout t timeout smbdata low period for interface reset 25 37 45 ms downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation _______________________________________________________________________________________ 5 typical operating characteristics (v cc = 3.3v, v stby = v cc , t a = +25?, unless otherwise noted.) software standby supply current vs. supply voltage max6693 toc01 supply voltage (v) standby supply current ( a) 3.2 3.5 3.4 3.3 3.1 3.6 3.23.1 3.3 3.4 3.5 3.6 3.7 3.83.0 3.0 supply current vs. supply voltage max6693 toc02 supply voltage (v) supply current ( a) 3.2 3.6 3.4 440420 460 480 500 540520 560 580400 3.0 low beta diode connected tochannel 1 with resistance cancellation and low beta -3 -2 -1 0 1 2 3 4 0 2 55 07 51 0 01 2 5 local temperature error vs. die temperature max6693 toc04 die temperature ( c) temperature error ( c) -5 -2-3 0 -1 21 -4 43 5 05 0 25 75 100 125 remote-diode temperature error vs. remote-diode temperature max6693 toc03 remote-diode temperature ( c) temperature error ( c) channel 2 channel 1 remote-diode temperature error vs. power-supply noise frequency max6693 toc05 frequency (mhz) temperature error ( c) -4 -3 -2 -1 0 1 2 3 4 5 -5 0.001 1.000 10.000 0.010 0.100 100mv p-p channel 2 channel 1 local temperature error vs. power-supply noise frequency max6693 toc06 frequency (mhz) temperature error ( c) 0.010 1.000 -4 -3 -2 -1 0 1 2 3 4 5 -5 0.001 10.000 0.100 100mv p-p ch 2 remote-diode temperature error vs. common-mode noise frequency max6693 toc07 frequency (mhz) temperature error ( c) 1.0 -4 -3 -2 -1 0 1 2 3 4 -5 0.1 10.0 100mv p-p downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation 6 _______________________________________________________________________________________ typical operating characteristics (continued) (v cc = 3.3v, v stby = v cc , t a = +25?, unless otherwise noted.) ch 2 remote-diode temperature error vs. capacitance max6693 toc09 capacitance (nf) temperature error ( c) 10 -4 -3 -2 -1 0 1 2 3 4 5 -5 1 100 pin description pin name function 1 dxp1 combined current source and a/d positive input for channel 1 remote transistor. connect to theemitter of a low-beta transistor. leave unconnected or connect to v cc if no remote transistor is used. place a 100pf capacitor between dxp1 and dxn1 for noise filtering. 2 dxn1 base inp ut for c hannel 1 rem ote d i od e. c onnect to the b ase of a p n p tem p er atur e- sensi ng tr ansi stor . 3 dxp2 combined current source and a/d positive input for channel 2 remote diode. connect to the anodeof a remote-diode-connected temperature-sensing transistor. leave unconnected or connect to v cc if no remote diode is used. place a 100pf capacitor between dxp2 and dxn2 for noise filtering. 4 dxn2 cathode input for channel 2 remote diode. connect the cathode of the channel 2 remote-diode-connected transistor to dxn2. 5 dxp3 combined current source and a/d positive input for channel 3 remote diode. connect to the anodeof a remote-diode-connected temperature-sensing transistor. leave unconnected or connect to v cc if no remote diode is used. place a 100pf capacitor between dxp3 and dxn3 for noise filtering. 6 dxn3 cathode input for channel 3 remote diode. connect the cathode of the channel 3 remote-diode-connected transistor to dxn3. 7 dxp4 combined current source and a/d positive input for channel 4 remote diode. connect to the anodeof a remote-diode-connected temperature-sensing transistor. leave unconnected or connect to v cc if no remote diode is used. place a 100pf capacitor between dxp4 and dxn4 for noise filtering. 8 dxn4 cathode input for channel 4 remote diode. connect the cathode of the channel 4 remote-diode-connected transistor to dxn4. ch 1 remote-diode temperature error vs. capacitance max6693 toc08 capacitance (nf) temperature error ( c) 10 -4 -3 -2 -1 0 1 2 3 4 5 -5 1 100 downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation _______________________________________________________________________________________ 7 detailed description the max6693 is a precision multichannel temperaturemonitor that features one local and six remote tempera- ture-sensing channels with a programmable alert threshold for each temperature channel and a program- mable overtemperature threshold for channels 1, 4, 5, and 6 (see figure 1). communication with the max6693 is achieved through the smbus serial interface and a dedicated alert pin. the alarm outputs, overt and alert , assert if the software-programmed temperature thresholds are exceeded. alert typically serves as an interrupt, while overt can be connected to a fan, sys- tem shutdown, or other thermal-management circuitry. adc conversion sequence in the default conversion mode, the max6693 starts theconversion sequence by measuring the temperature on channel 1, followed by 2, 3, local channel, 4, 5, and 6. the conversion result for each active channel is stored in the corresponding temperature data register. low-power standby mode enter software standby mode by setting the stop bit to1 in the configuration 1 register. enter hardware standby by pulling stby low. software standby mode disables the adc and reduces the supply current to approxi-mately 3?. hardware standby mode halts the adc clock, but the supply current is approximately 350?.during either software or hardware standby, data is retained in memory. during hardware standby, the smbus interface is inactive. during software standby, the smbus interface is active and listening for commands. the timeout is enabled if a start condition is recognized on smbus. activity on the smbus causes the supply cur- rent to increase. if a standby command is received while a conversion is in progress, the conversion cycle is inter- rupted, and the temperature registers are not updated. the previous data is not changed and remains available. pin name function 9 dxp5 combined current source and a/d positive input for channel 5 remote diode. connect to the anodeof a remote-diode-connected temperature-sensing transistor. leave unconnected or connect to v cc if no remote diode is used. place a 100pf capacitor between dxp5 and dxn5 for noise filtering. 10 dxn5 cathode input for channel 5 remote diode. connect the cathode of the channel 5 remote-diode-connected transistor to dxn5. 11 dxn6 cathode input for channel 6 remote diode. connect the cathode of the channel 6 remote-diode-connected transistor to dxn6. 12 dxp6 combined current source and a/d positive input for channel 6 remote diode. connect to the anodeof a remote-diode-connected temperature-sensing transistor. leave unconnected or connect to v cc if no remote diode is used. place a 100pf capacitor between dxp6 and dxn6 for noise filtering. 13 stby acti ve- low s tand b y inp ut. d r i ve s tby l og i c- l ow to p l ace the m ax 6693 i n stand b y m od e, or l og i c- hi g h for op er ate m od e. tem p er atur e and thr eshol d d ata ar e r etai ned i n stand b y m od e. 14 n.c. no connection. must be connected to ground. 15 overt overtemperature active-low, open-drain output. overt asserts low when the temperature of channels 1, 4, 5, and 6 exceeds the programmed threshold limit. 16 v cc supply voltage input. bypass to gnd with a 0.1? capacitor. 17 alert smbus alert (interrupt), active-low, open-drain output. alert asserts low when the temperature of any channel exceeds the programmed alert threshold. 18 smbdata smbus serial data input/output. connect to a pullup resistor. 19 smbclk smbus serial clock input. connect to a pullup resistor. 20 gnd ground pin description (continued) downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation 8 _______________________________________________________________________________________ operating-current calculation the max6693 operates at different operating-currentlevels depending on how many external channels are in use. assume that i cc1 is the operating current when the max6693 is converting the remote channel 1 andi cc2 is the operating current when the max6693 is con- verting the other channels. for the max6693 withremote channel 1 and n other remote channels con- nected, the operating current is: i cc = (2 x i cc1 + i cc2 + n x i cc2 )/(n + 3) smbus digital interface from a software perspective, the max6693 appears asa series of 8-bit registers that contain temperature mea- surement data, alarm threshold values, and control bits. a standard smbus-compatible, 2-wire serial interface is used to read temperature data and write control bits and alarm threshold data. the same smbus slave address also provides access to all functions. figure 1. internal block diagram dxp1 dxn1 dxp2 dxn2 dxp3 dxn3 dxp4 dxn4 dxp5 dxn5 dxp6 dxn6 input buffer current sources, beta compen- sation and mux v cc ref adc command byte remote temperatures local temperatures register bank alert threshold overt threshold alert response address alarm alu smbus interface max6693 smbclk smbdata overt alert stby downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation _______________________________________________________________________________________ 9 the max6693 employs four standard smbus protocols:write byte, read byte, send byte, and receive byte (figure 2). the shorter receive byte protocol allows quicker transfers, provided that the correct data regis- ter was previously selected by a read byte instruction. use caution with the shorter protocols in multimaster systems, since a second master could overwrite the command byte without informing the first master. figure 3 is the smbus write-timing diagram and figure 4 is the smbus read-timing diagram. the remote diode 1 measurement channel provides 11 bits of data (1 lsb = 0.125?). all other temperature- measurement channels provide 8 bits of temperature data (1 lsb = 1?). the 8 most significant bits (msbs)can be read from the local temperature and remote temperature registers. the remaining 3 bits for remote diode 1 can be read from the extended temperature register. if extended resolution is desired, the extended resolution register should be read first. this prevents the most significant bits from being overwritten by new conversion results until they have been read. if the most significant bits have not been read within an smbus timeout period (nominally 37ms), normal updating con- tinues. table 1 shows the main temperature register (high-byte) data format, and table 2 shows the extend- ed resolution register (low-byte) data format. figure 2. smbus protocols temp (c) digital output > +127 0111 1111 +127 0111 1111 +126 0111 1110 +25 0001 1001 0 0000 0000 < 0 0000 0000 diode fault (open or short) 1111 1111 table 1. main temperature register (high-byte) data format temp (c) digital output 0 000x xxxx +0.125 001x xxxx +0.250 010x xxxx +0.375 011x xxxx +0.500 100x xxxx +0.625 101x xxxx +0.750 110x xxxx +0.875 111x xxxx table 2. extended resolution temperatureregister (low-byte) data format s address wr ack ack p data ack command 7 bits 1 8 bits 8 bits slave address: equiva-lent to chip-select line of a 3-wire interface data byte: data goes into the registerset by the command byte (to set thresholds, configuration masks, and sampling rate) write byte format s address address wr ack ack p s rd ack /// data command 7 bits 7 bits 8 bits 8 bits read byte format slave address: equiva-lent to chip select line command byte: selectswhich register you are reding from sp address wr ack ack command 7 bits 8 bits send byte format command byte: sends com-mand with no data, usually used for one-shot command sp address rd ack /// data 7 bits 8 bits receive byte format data byte: reads data fromthe register commanded by the last read byte or write byte transmission; also used for smbus alert response return address slave address: repeateddue to change in data- flow direction data byte: reads fromthe register set by the command byte s = start condition.p = stop condition. shaded = slave transmission./// = not acknowledged. downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation 10 ______________________________________________________________________________________ diode fault detection if a channel? input dxp_ and dxn_ are left open, themax6693 detects a diode fault. an open diode fault does not cause either alert or overt to assert. a bit in the sta- tus register for the corresponding channel is set to 1 and thetemperature data for the channel is stored as all 1s (ffh). it takes approximately 4ms for the max6693 to detect a diode fault. once a diode fault is detected, the max6693 goes to the next channel in the conversion sequence. alarm threshold registers there are 11 alarm threshold registers that store over-tem-perature alert and overt threshold values. seven of these registers are dedicated to storing one local alert tem-perature threshold limit and six remote alert temperature threshold limits (see the alert interrupt mode section). the remaining four registers are dedicated to remote chan-nels 1, 4, 5, and 6 to store overtemperature threshold limits (see the overt overtemperature alarms section). access to these registers is provided through the smbus interface. alert interrupt mode an alert interrupt occurs when the internal or external temperature reading exceeds a high-temperature limit(user programmable). the alert interrupt output signal can be cleared by reading the status register(s) associ-ated with the fault(s) or by successfully responding to an alert response address transmission by the master. in both cases, the alert is cleared but is reasserted at the end of the next conversion if the fault condition still exists. the interrupt does not halt automatic conversions. the alert output is open-drain so that multiple devices can share a common interrupt line. all alert interrupts can be masked using the configuration 2 register. thepor state of these registers is shown in table 3. smbclk ab cd e fg h i j k smbdata t su:sta t hd:sta t low t high t su:dat t hd:dat t su:sto t buf a = start condition.b = msb of address clocked into slave. c = lsb of address clocked into slave. d = r/w bit clocked into slave. e = slave pulls smbdata line low. l m f = acknowledge bit clocked into master.g = msb of data clocked into master. h = lsb of data clocked into master. i = master pulls data line low. j = acknowledge clocked into slave.k = acknowledge clock pulse. l = stop condition. m = new start condition. figure 3. smbus write-timing diagram smbclk a = start condition.b = msb of address clocked into slave. c = lsb of address clocked into slave. d = r/w bit clocked into slave. ab cd e fg hi j smbdata t su:sta t hd:sta t low t high t su:dat t su:sto t buf lm k e = slave pulls smbdata line low.f = acknowledge bit clocked into master. g = msb of data clocked into slave. h = lsb of data clocked into slave. i = master pulls data line low.j = acknowledge clocked into slave. k = acknowledge clock pulse. l = stop condition. m = new start condition. figure 4. smbus read-timing diagram downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation ______________________________________________________________________________________ 11 alert response address the smbus alert response interrupt pointer providesquick fault identification for simple slave devices that lack the complex logic needed to be a bus master. upon receiving an interrupt signal, the host master can broadcast a receive byte transmission to the alert response slave address (see the slave address sec- tion). then, any slave device that generated an inter-rupt attempts to identify itself by putting its own address on the bus. the alert response can activate several different slave devices simultaneously, similar to the i 2 c general call. if more than one slave attempts to respond, bus arbitra-tion rules apply, and the device with the lower address code wins. the losing device does not generate an acknowledgment and continues to hold the alert line low until cleared. (the conditions for clearing an alertvary depending on the type of slave device.) successful completion of the alert response protocol clears the output latch. if the condition that caused the alert still exists, the max6693 reasserts the alert interrupt at the end of the next conversion. overt overtemperature alarms the max6693 has four overtemperature registers thatstore remote alarm threshold data for the overt output. overt is asserted when a channel? measured temper- ature is greater than the value stored in the correspond-ing threshold register. overt remains asserted until the temperature drops below the programmed thresholdminus 4? hysteresis. an overtemperature output can be used to activate a cooling fan, send a warning, initi- ate clock throttling, or trigger a system shutdown to pre- vent component damage. see table 3 for the por state of the overtemperature threshold registers. command byte functions the 8-bit command byte register (table 3) is the masterindex that points to the various other registers within the max6693. this register? por state is 0000 0000. configuration byte functions there are three read-write configuration registers(tables 4, 5, and 6) that can be used to control the max6693? operation. configuration 1 register the configuration 1 register (table 4) has several func-tions. bit 7 (msb) is used to put the max6693 either in software standby mode (stop) or continuous conver- sion mode. bit 6 resets all registers to their por condi- tions and then clears itself. bit 5 disables the smbus timeout. bit 3 enables resistance cancellation on chan- nel 1. see the series resistance cancellation section for more details. bit 2 enables beta compensation onchannel 1. see the beta compensation section for more details. the remaining bits of the configuration 1 regis-ter are not used. the por state of this register is 0000 1100 (0ch). configuration 2 register the configuration 2 register functions are described intable 5. bits [6:0] are used to mask the alert interrupt output. bit 6 masks the local alert interrupt and bits 5through bit 0 mask the remote alert interrupts. the power-up state of this register is 0000 0000 (00h). configuration 3 register table 6 describes the configuration 3 register. bits 5, 4, 3,and 0 mask the overt interrupt output for channels 6, 5, 4, and 1. the remaining bits, 7, 6, 2, and 1, are reserved.the power-up state of this register is 0000 0000 (00h). status register functions status registers 1, 2, and 3 (tables 7, 8, and 9) indicatewhich (if any) temperature thresholds have been exceeded and if there is an open-circuit or short-circuit fault detected with the external sense junctions. status register 1 indicates if the measured temperature has exceeded the threshold limit set in the alert registers for the local or remote-sensing diodes. status register 2indicates if the measured temperature has exceeded the threshold limit set in the overt registers. status register 3 indicates if there is a diode fault (open orshort) in any of the remote-sensing channels. bits in the alert status register clear by a successful read, but set again after the next conversion unless the fault is corrected, either by a drop in the measured tem- perature or an increase in the threshold temperature. the alert interrupt output follows the status flag bit. once the alert output is asserted, it can be deasserted by either reading status register 1 or bysuccessfully responding to an alert response address. in both cases, the alert is cleared even if the fault condi- downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation 12 ______________________________________________________________________________________ register address (hex) por state (hex) read/ write description local 07 00 r read local temperature register remote 1 01 00 r read channel 1 remote temperature register remote 2 02 00 r read channel 2 remote temperature register remote 3 03 00 r read channel 3 remote temperature register remote 4 04 00 r read channel 4 remote temperature register remote 5 05 00 r read channel 5 remote temperature register remote 6 06 00 r read channel 6 remote temperature register configuration 1 41 0c r/w read/write configuration register 1 configuration 2 42 00 r/w read/write configuration register 2 configuration 3 43 00 r/w read/write configuration register 3 status1 44 00 r read status register 1 status2 45 00 r read status register 2 status3 46 00 r read status register 3 local alert high limit 17 5a r/w read/write local alert high-temperature threshold limit register remote 1 alert high limit 11 6e r/w read/write channel 1 remote-diode alert high-temperaturethreshold limit register remote 2 alert high limit 12 7f r/w read/write channel 2 remote-diode alert high-temperaturethreshold limit register remote 3 alert high limit 13 64 r/w read/write channel 3 remote-diode alert high-temperaturethreshold limit register remote 4 alert high limit 14 64 r/w read/write channel 4 remote-diode alert high-temperaturethreshold limit register remote 5 alert high limit 15 64 r/w read/write channel 5 remote-diode alert high-temperaturethreshold limit register remote 6 alert high limit 16 64 r/w read/write channel 6 remote-diode alert high-temperaturethreshold limit register remote 1 overt high limit 21 6e r/w read/write channel 1 remote-diode overtemperature threshold limit register remote 4 overt high limit 24 7f r/w read/write channel 4 remote-diode overtemperature threshold limit register remote 5 overt high limit 25 5a r/w read/write channel 5 remote-diode overtemperature threshold limit register remote 6 overt high limit 26 5a r/w read/write channel 6 remote-diode overtemperature threshold limit register remote 1 extendedtemperature 09 00 r read channel 1 remote-diode extended temperature register manufacturer id 0a 4d r read manufacturer id table 3. command byte register bit assignment downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation ______________________________________________________________________________________ 13 tion exists, but the alert output reasserts at the end of the next conversion. the bits indicating the fault for theovert interrupt output clear only on reading the status 2 register even if the fault conditions still exist. reading thestatus 2 register does not clear the overt interrupt out- put. to eliminate the fault condition, either the measuredtemperature must drop below the temperature threshold minus the hysteresis value (4?), or the trip temperature must be set at least 4? above the current temperature. applications information remote-diode selection the max6693 directly measures the die temperature ofcpus and other ics that have on-chip temperature- sensing diodes (see the typical application circuit ) or it can measure the temperature of a discrete diode-connected transistor. effect of ideality factor the accuracy of the remote temperature measure-ments depends on the ideality factor (n) of the remote ?iode?(actually a transistor). the max6693 is opti- mized for n = 1.006 (channel 1) and n = 1.008 (chan- nels 2?). a thermal diode on the substrate of an ic isnormally a pnp with the base and emitter brought out to the collector (diode connection) grounded. dxp_ must be connected to the anode (emitter) and dxn_ must be connected to the cathode (base) of this pnp. if a sense transistor with an ideality factor other than 1.006 or 1.008 is used, the output data is different from the data obtained with the optimum ideality factor. fortunately, the difference is predictable. assume a remote-diode sensor designed for a nominal ideality factor n nominal is used to measure the temperature of a diode with adifferent ideality factor n 1 . the measured temperature t m can be corrected using: bit name por state function 7 (msb) stop 0 standby-mode control bit. if stop is set to logic 1, the max6693 stopsconverting and enters standby mode. 6 por 0 reset bit. set to logic 1 to put the device into its power-on state. this bit is self-clearing. 5 timeout 0 timeout enable bit. set to logic 0 to enable smbus timeout. 4 reserved 0 reserved. must set to 0. 3 resistance cancellation 1 resistance cancellation bit. when set to logic 1, the max6693 cancels seriesresistance in the channel 1 thermal diode. 2 beta compensation 1 beta compensation bit. when set to logic 1, the max6693 compensates for lowbeta in the channel 1 thermal sensing transistor. 1 reserved 0 0 reserved 0 table 4. configuration 1 register table 5. configuration 2 register bit name por state function 7 (msb) reserved 0 6 mask local alert 0 local alert mask. set to logic 1 to mask local channel alert . 5 mask alert 6 0 channel 6 alert mask. set to logic 1 to mask channel 6 alert . 4 mask alert 5 0 channel 5 alert mask. set to logic 1 to mask channel 5 alert . 3 mask alert 4 0 channel 4 alert mask. set to logic 1 to mask channel 4 alert . 2 mask alert 3 0 channel 3 alert mask. set to logic 1 to mask channel 3 alert . 1 mask alert 2 0 channel 2 alert mask. set to logic 1 to mask channel 2 alert . 0 mask alert 1 0 channel 1 alert mask. set to logic 1 to mask channel 1 alert . downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation 14 ______________________________________________________________________________________ where temperature is measured in kelvin andn nomimal for channel 1 of the max6693 is 1.009. as an example, assume you want to use the max6693 witha cpu that has an ideality factor of 1.002. if the diode has no series resistance, the measured data is related to the real temperature as follows: for a real temperature of +85? (358.15k), the mea- sured temperature is +84.41? (357.56k), an error of -0.590?. series resistance cancellation some thermal diodes on high-power ics can haveexcessive series resistance, which can cause tempera- ture measurement errors with conventional remote tem- perature sensors. channel 1 of the max6693 has a series resistance cancellation feature (enabled by bit 3 of the configuration 1 register) that eliminates the effect of diode series resistance. set bit 3 to 1 if the series resistance is large enough to affect the accuracy of channel 1. the series resistance cancellation function increases the conversion time for channel 1 by 125ms. this feature cancels the bulk resistance of the sensor and any other resistance in series (wire, contact resis- tance, etc.). the cancellation range is from 0 to 100 . beta compensation the max6693 is optimized for use with a substrate pnpremote-sensing transistor on the die of the target ic. dxp1 connects to the emitter of the sensing transistor and dxn1 connects to the base. the collector is grounded. such transistors can have very low beta (less than 1) when built in processes with 65nm and smaller geometries. because of the very low beta, stan- dard ?emote diode?temperature sensors may exhibit large errors when used with these transistors. channel 1 of the max6693 incorporates a beta compensation function that, when enabled, eliminates the effect of low beta values. this function is enabled at power-up using bit 2 of the configuration 1 register. whenever low beta compensation is enabled, series-resistance cancella- tion must be enabled. discrete remote diodes when the remote-sensing diode is a discrete transistor,its collector and base must be connected together. table 10 lists examples of discrete transistors that are appropriate for use with the max6693. the transistor must be a small-signal type with a relatively high for- ward voltage; otherwise, the a/d input voltage range can be violated. the forward voltage at the highest expected temperature must be greater than 0.25v at 10?, and at the lowest expected temperature, the for- ward voltage must be less than 0.95v at 100?. large power transistors must not be used. also, ensure that the base resistance is less than 100 . tight specifica- tions for forward current gain (50 < ?< 150, for exam-ple) indicate that the manufacturer has good process controls and that the devices have consistent v be char- tt n n tt actual m nominal mm = ? ? ? ? ? ? = ? ? ? ? ? ? = 1 1 009 1 002 1 00699 .. (. ) tt n n m actual nominal = ? ? ? ? ? ? 1 table 6. configuration 3 register bit name por state function 7 (msb) reserved 0 6 reserved 0 5 mask overt 6 0 channel 6 remote-diode overt mask bit. set to logic 1 to mask channel 6 overt . 4 mask overt 5 0 channel 5 remote-diode overt mask bit. set to logic 1 to mask channel 5 overt . 3 mask overt 4 0 channel 4 remote-diode overt mask bit. set to logic 1 to mask channel 4 overt . 2 reserved 0 1 reserved 0 0 mask overt 1 0 channel 1 remote-diode overt mask bit. set to logic 1 to mask channel 1 overt . downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation ______________________________________________________________________________________ 15 acteristics. manufacturers of discrete transistors do notnormally specify or guarantee ideality factor. this is normally not a problem since good-quality discrete transistors tend to have ideality factors that fall within a relatively narrow range. we have observed variations in remote temperature readings of less than ?? with a variety of discrete transistors. still, it is good design practice to verify good consistency of temperature readings with several discrete transistors from any manufacturer under consideration. unused diode channels if one or more of the remote diode channels is notneeded, disconnect the dxp and dxn inputs for that channel, or connect the dxp input to v cc . the status register indicates a diode "fault" for this channel and thechannel is ignored during the temperature-measure- ment sequence. it is also good practice to mask any unused channels immediately upon power-up by set-ting the appropriate bits in the configuration 2 and configuration 3 registers. this will prevent unused channels from causing alert or overt to assert. thermal mass and self-heating when sensing local temperature, the max6693 mea-sures the temperature of the pcb to which it is soldered. the leads provide a good thermal path between the pcb traces and the die. as with all ic temperature sen- sors, thermal conductivity between the die and the ambient air is poor by comparison, making air tempera- ture measurements impractical. because the thermal mass of the pcb is far greater than that of the max6693, the device follows temperature changes on the pcb with little or no perceivable delay. when mea- suring the temperature of a cpu or other ic with an on- chip sense junction, thermal mass has virtually no table 7. status 1 register bit name por state function 7 (msb) reserved 0 6 local alert 0 local channel high-alert bit. this bit is set to logic 1 when the localtemperature exceeds the temperature threshold limit in the local alert high- limit register. 5 remote 6 alert 0 channel 6 remote-diode high-alert bit. this bit is set to logic 1 when thechannel 6 remote-diode temperature exceeds the temperature threshold limit in the remote 6 alert high-limit register. 4 remote 5 alert 0 channel 5 remote-diode high-alert bit. this bit is set to logic 1 when thechannel 5 remote-diode temperature exceeds the programmed temperature threshold limit in the remote 5 alert high-limit register. 3 remote 4 alert 0 channel 4 remote-diode high-alert bit. this bit is set to logic 1 when thechannel 4 remote-diode temperature exceeds the temperature threshold limit in the remote 4 alert high-limit register. 2 remote 3 alert 0 channel 3 remote-diode high-alert bit. this bit is set to logic 1 when thechannel 3 remote-diode temperature exceeds the programmed temperature threshold limit in the remote 3 alert high-limit register. 1 remote 2 alert 0 channel 2 remote-diode high-alert bit. this bit is set to logic 1 when thechannel 2 remote-diode temperature exceeds the temperature threshold limit in the remote 2 alert high-limit register. 0 remote 1 alert 0 channel 1 remote-diode high-alert bit. this bit is set to logic 1 when thechannel 1 remote-diode temperature exceeds the temperature threshold limit in the remote 1 alert high-limit register. downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation 16 ______________________________________________________________________________________ bit name por state function 7 (msb) reserved 0 6 reserved 0 5 remote 6 overt 0 channel 6 remote-diode overtemperature status bit. this bit is set to logic 1 when the channel 6 remote-diode temperature exceeds the temperature threshold limit in the remote 6 overt high-limit register. 4 remote 5 overt 0 channel 5 remote diode overtemperature status bit. this bit is set to logic 1when the channel 5 remote-diode temperature exceeds the temperature threshold limit in the remote 5 overt high-limit register. 3 remote 4 overt 0 channel 4 remote diode overtemperature status bit. this bit is set to logic 1when the channel 4 remote-diode temperature exceeds the temperature threshold limit in the remote 4 overt high-limit register. 2 reserved 0 1 reserved 0 0 remote 1 overt 0 channel 1 remote-diode overtemperature status bit. this bit is set to logic 1 when the channel 1 remote-diode temperature exceeds the temperature threshold limit in the remote 1 overt high-limit register. table 8. status 2 register bit name por state function 7 (msb) reserved 0 6 diode fault 6 0 channel 6 remote-diode fault bit. this bit is set to 1 when dxp6 and dxn6are open circuit or when dxp6 is connected to v cc . 5 diode fault 5 0 channel 5 remote-diode fault bit. this bit is set to 1 when dxp5 and dxn5are open circuit or when dxp5 is connected to v cc . 4 diode fault 4 0 channel 4 remote-diode fault bit. this bit is set to 1 when dxp4 and dxn4are open circuit or when dxp4 is connected to v cc . 3 diode fault 3 0 channel 3 remote-diode fault bit. this bit is set to 1 when dxp3 and dxn3are open circuit or when dxp3 is connected to v cc . 2 diode fault 2 0 channel 2 remote-diode fault bit. this bit is set to 1 when dxp2 and dxn2are open circuit or when dxp2 is connected to v cc . 1 diode fault 1 0 channel 1 remote-diode fault bit. this bit is set to 1 when dxp1 and dxn1are open circuit or when dxp1 is connected to v cc . 0 reserved 0 table 9. status 3 register downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation ______________________________________________________________________________________ 17 effect; the measured temperature of the junction tracksthe actual temperature within a conversion cycle. when measuring temperature with discrete remote tran- sistors, the best thermal response times are obtained with transistors in small packages (i.e., sot23 or sc70). take care to account for thermal gradients between the heat source and the sensor, and ensure that stray air currents across the sensor package do not interfere with measurement accuracy. self-heating does not signifi- cantly affect measurement accuracy. remote-sensor self-heating due to the diode current source is negligible. adc noise filtering the integrating adc has good noise rejection for low-frequency signals, such as power-supply hum. in environ- ments with significant high-frequency emi, connect an external 100pf capacitor between dxp_ and dxn_. larger capacitor values can be used for added filtering, but do not exceed 100pf because it can introduce errors due to the rise time of the switched current source. high- frequency noise reduction is needed for high-accuracy remote measurements. noise can be reduced with careful pcb layout as discussed in the pcb layout section. slave address the slave address for the max6693 is shown in table 11. pcb layout follow these guidelines to reduce the measurementerror when measuring remote temperature: 1) place the max6693 as close as is practical to the remote diode. in noisy environments, such as a com-puter motherboard, this distance can be 4in to 8in (typ). this length can be increased if the worst noise sources are avoided. noise sources include crts, clock generators, memory buses, and pci buses. 2) do not route the dxp-dxn lines next to the deflec- tion coils of a crt. also, do not route the tracesacross fast digital signals, which can easily intro- duce +30? error, even with good filtering. 3) route the dxp and dxn traces in parallel and in close proximity to each other. each parallel pair of tracesshould go to a remote diode. route these traces away from any higher voltage traces, such as +12vdc. leakage currents from pcb contamination must be dealt with carefully since a 20m leakage path from dxp to ground causes about +1? error. if high-volt-age traces are unavoidable, connect guard traces to gnd on either side of the dxp-dxn traces (figure 5). 4) route through as few vias and crossunders as possi- ble to minimize copper/solder thermocouple effects. 5) use wide traces when practical. 5mil to 10mil traces are typical. be aware of the effect of trace resistance ontemperature readings when using long, narrow traces. 6) when the power supply is noisy, add a resistor (up to 47 ) in series with v cc . 5?0 mils 5?0 mils 5?0 milsminimum 5?0 mils gnd dxp dxn gnd figure 5. recommended dxp-dxn pcb traces. the two outer guard traces are recommended if high-voltage traces near the dxn and dxp traces. manufacturer model no. central semiconductor (usa) cmpt3904 rohm semiconductor (usa) sst3904 samsung (korea) kst3904-tf siemens (germany) smbt3904 zetex (england) fmmt3904ct-nd table 10. remote-sensors transistormanufacturer (for channels 2?) note: discrete transistors must be diode connected (base shorted to collector). device address a7 a6 a5 a4 a3 a2 a1 a0 1001101r / w table 11. slave address downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation 18 ______________________________________________________________________________________ twisted-pair and shielded cables use a twisted-pair cable to connect the remote sensorfor remote-sensor distances longer than 8in or in very noisy environments. twisted-pair cable lengths can be between 6ft and 12ft before noise introduces excessive errors. for longer distances, the best solution is a shielded twisted pair like that used for audio micro- phones. for example, belden #8451 works well for dis- tances up to 100ft in a noisy environment. at the device, connect the twisted pair to dxp and dxn andthe shield to gnd. leave the shield unconnected at the remote sensor. for very long cable runs, the cable? parasitic capacitance often provides noise filtering, so the 100pf capacitor can often be removed or reduced in value. cable resistance also affects remote-sensor accuracy. for every 1 of series resistance the error is approximately +0.5?. 2019 18 17 16 15 14 13 12 3 4 5 6 7 8 gnd smbclk smbdata dxn2 dxp2 dxn1 dxp1 top view v cc n.c.stby dxn4 dxp4 dxn3 dxp3 1211 9 10 dxp6dxn6 dxn5 dxp5 max6693 tssop + alert overt pin configuration chip information process: bicmos downloaded from: http:///
max6693 7-channel precision temperature monitor with beta compensation 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 ____________________ 19 2008 maxim integrated products is a registered trademark of maxim integrated products, inc. package type package code document no. 20 tssop u20-2 21-0066 package information for the latest package outline information, go to www.maxim-ic.com/packages . downloaded from: http:///

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