general description the MAX6662 is a 12-bit + sign temperature sensor combined with a programmable overtemperature alarm and a 3-wire (spi?-compatible) serial interface in a sin- gle package. it converts its die temperature into digital values using an internal analog-to-digital converter (adc). the temperature data is stored in a temperature register as a 13-bit word, which allows 0.0625c resolu- tion. the temperature data is readable at any time through the serial interface. the operating temperature range is -55c to +150c. the MAX6662 provides two programmable watchdog interrupt outputs. alert is used for lower temperature warning functions, while ot is used for higher tempera- ture-critical functions, such as power-supply shutdown. the MAX6662 features a shutdown mode that saves power by disabling everything except the serial inter- face. the temperature sensor is available in an 8-pin so package. applications hvac refrigeration automotive test equipment features ? 12-bit + sign, 0.0625c resolution ? accuracy 1c max (+30c to +50c) 1.6c max (0c to +70c) 2.5c max (-20c to +85c) 2.5 typ (+150c) ? extended temperature measurement range -55c to +150c ? low average supply current, 125a (typ) ? shutdown mode to minimize power consumption in portable applications ? two programmable temperature fault outputs ? switchable fault queue to eliminate false tripping in noisy environments MAX6662 12-bit + sign temperature sensor with spi-compatible serial interface ________________________________________________________________ maxim integrated products 1 alert ot gnd 1 2 8 7 v cc nc cs sio sclk so top view 3 4 6 5 MAX6662 pin configuration ordering information 10k ? 10k ? 0.1 f v cc ot alert sio sclk cs system controller v cc = +3v to +5.5v heat sources MAX6662 typical operating circuit 19-2121; rev 0; 7/01 part temp. range pin-package MAX6662msa -55 c to +150 c 8 so spi is a trademark of motorola, inc. for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxims website at www.maxim-ic.com.
MAX6662 12-bit + sign temperature sensor with spi-compatible serial interface 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v cc = +3v to +5.5v, t a = -55c to +125c, unless otherwise noted. typical values are at t a = +25c and v cc = +3.3v.) 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. all voltages are referenced to gnd v cc ...........................................................................-0.3v to +6v alert , ot ................................................................-0.3v to +6v sio, sclk, cs ............................................-0.3v to (v cc + 0.3v) sio current .......................................................-10ma to +50ma continuous current into any pin (except nc).................10ma continuous power dissipation (t a = +70c) 8-pin so (derate 5.9mw/c above +70c)..................471mw operating temperature range (note 1) ..........-55c to +150c junction temperature ......................................................+150c storage temperature range .............................-65c to +150c lead temperature (soldering, 10s) .................................+300c note 1: the MAX6662 is not recommended to operate above +125c for an extended period of time. parameter symbol conditions min typ max units temperature to digital-converter characteristics +30c t a +50c, v cc = +3.3v -1.0 0.4 +1.0 0c t a +70c, v cc = +3.3v -1.6 0.7 +1.6 -20c t a +85c, v cc = +3.3v -2.5 1.0 +2.5 -40c t a +100c, v cc = +3.3v -3.0 1.2 +3.0 -55c t a +125c, v cc = +3.3v -4.0 1.5 +4.0 accuracy t a +150c, v cc = +3.3v 2.5 c power-supply rejection ratio psrr 0.2 0.5 c/v resolution 0.0625 c supply voltage range v cc 3.0 5.5 v v cc = +5.5v 150 average operating current v cc = +3.0v 125 a v cc = +5.5v 300 600 peak operating current (note 2) v cc = +3.0v 300 500 a v cc = +5.5v 8 22 shutdown supply current v cc = +3.0v 4 15 a power-on-reset threshold v por 2.0 2.5 v power-on-reset threshold hysteresis 90 mv conversion time t conv 0.25 s temperature update frequency 2hz serial interface (sio, sclk, cs, alert, ot ) input low voltage v il 0.8 v input high voltage v ih 0.7 v cc v input/output leakage current i leak v in = gnd or v cc -5 +5 a input capacitance c in 5pf output low sink current i ol alert , ot , v ol = 0.6v 3 ma output high voltage v oh i sio = 1.6ma source v cc - 0.4 v output low volta g ev ol i sio = 1.6ma sink 0.4 v
MAX6662 12-bit + sign temperature sensor with spi-compatible serial interface _______________________________________________________________________________________ 3 -3 0 -1 -2 1 2 3 -50 30 10 -30 -10 50 70 90 110 130 150 temperature error vs. temperature MAX6662 toc01 temperature ( c) temperature error ( c) v cc = +5.0v v cc = +3.3v v cc = +3.0v 0 20 10 40 30 50 60 80 70 90 -0.45-0.35 -0.25 -0.15 0.05 0.15 0.25 0.35 0.45 temperature error distribtution MAX6662 toc02 temperature error ( c) percentage of samples (%) note: devices trimmed at t a = +30 c 200 samples t a = +30 c 100 120 160 140 180 200 supply current vs. temperature MAX6662 toc03 temperature ( c) supply current ( a) -50 50 0 100 150 v cc = +5.0v average over 2 v cc = +3.3v v cc = +3.0v typical operating characteristics (v cc = +3v, t a = +25c, unless otherwise noted.) electrical characteristics (continued) (v cc = +3v to +5.5v, t a = -55c to +125c, unless otherwise noted. typical values are at t a = +25c and v cc = +3.3v.) parameter symbol conditions min typ max units serial interface timing serial clock frequency f sclk 2.5 mhz sclk high pulse width t ch 200 ns sclk low pulse width t cl 200 ns cs high pulse width t csw 200 ns sclk fall to output data valid t do c load = 100pf 100 ns cs fall to sclk rise t css 100 ns cs rise to output disable t tr c load = 100pf 100 ns cs to sclk hold time t csh 0ns sio to sclk setup time t ds 100 ns sio to sclk hold time t dh 0ns output fall time t f 10 ns note 2 : peak operating current measured during conversion.
MAX6662 12-bit + sign temperature sensor with spi-compatible serial interface 4 _______________________________________________________________________________________ 0 4 2 8 6 10 12 -50 50 0 100 150 shutdown current vs. temperature MAX6662 toc04 temperature ( c) shutdown current ( a) v cc = +5.0v v cc = +3.0v v cc = +3.3v typical operating characteristics (continued) (v cc = +3v, t a = +25c, unless otherwise noted.) pin description detailed description the MAX6662 continuously converts its die tempera- ture into a digital value using its integrated adc. temperature data is updated twice a second. the resulting data is readable at any time through the spi- compatible serial interface. figure 1 shows the simplified functional diagram of the MAX6662. its internal current sources force 100a and 10a currents through a diode (diode-connected tran- sistor), while the integrating adc measures the voltage difference. the difference in voltage corresponds to the die temperature. the result is stored in the temperature register. the control logic unit compares the tempera- ture and the temperature limit settings stored in the reg- isters to determine whether a fault condition has occurred. temperature fault alert the alert is an open-drain active-low (default, also programmable active-high) output used to alert the sys- tem to temperature faults. alert can be programmed to operate in either one of two modes: comparator or interrupt mode. interrupt mode in the interrupt mode, the MAX6662 alert pin asserts an alarm for an undertemperature (t low ) fault, as well as for an overtemperature (t high ) fault. once either fault has occurred, it remains active indefinitely, regard- less of condition. alert is unconditionally deasserted (even if temperature is still out of limits) by reading the temperature register. alert only asserts again if the temperature crosses the hysteresis, thereby corre- sponding to the fault (t low or t high ) that initially set the alert . pin name function 1 sclk serial-clock input 2 cs chip select input. set low to enable the serial interface for data input/output. 3 sio serial-data input/output. bidirectional data input and output for serial interface. 4 gnd ground 5 ot overtemperature output. open-drain output requires a pullup resistor to v cc . 6 alert alert output. open-drain output requires a pullup resistor to v cc . 7 nc no connection. do not make a connection to this pin. 8v cc supply voltage input. bypass to gnd with a 0.1f capacitor as close to v cc as possible.
MAX6662 12-bit + sign temperature sensor with spi-compatible serial interface _______________________________________________________________________________________ 5 for example: if t high is set to 100c and t hyst is set to 20c, alert does not assert until temperature exceeds 100c. if the temperature is then read through the serial interface, alert deasserts. alert asserts again when temperature is less than 80c (figure 2). comparator mode in the comparator mode, alert is asserted when tem- perature exceeds the value in the t high register, or is lower than the value in the t low register. alert deasserts when temperature is less than t high - t hyst or greater than t low + t hyst . reading the registers does not deassert alert . for example: if t high is set to 100c and t low is set to 80c, alert does not assert until temperature exceeds 100c, or is below 80c. then, alert only deasserts if temperature is less than t high - t hyst or greater than t low + t hyst . overtemperature alert ot operates only in comparator mode. the ot pin is asserted when the temperature exceeds t max , and deasserted when the temperature drops below t max - t hyst . a read operation does not reset ot . ot is an open-drain active-low (default) output, but can be programmed to active-high. temperature ot serial interface v cc sio sclk configuration cs alert t low t high t max t hyst 12 -bit + sign adc figure 1. MAX6662 simplified functional diagram t i - t st t i t o t o t st aert temperatre ast interrpt missed, bt tresod sti anes to t i . temperatre read figure 2. example of alert operation in interrupt mode
MAX6662 12-bit + sign temperature sensor with spi-compatible serial interface 6 _______________________________________________________________________________________ temperature fault queue the activation of alert and ot is subject to the depth of the fault queue. if the fault queue bit in the configuration register is enabled, alert or ot does not assert until four consecutive temperature conver- sions are at fault. for example: if t high is set to 100c, t hyst is set to 20c, alert is set to interrupt mode, and fault queue is enabled, alert does not assert until four consecu- tive conversions exceed 100c. if the temperature is then read through the serial interface, alert deasserts. alert asserts again when four consecutive conversions are less than 80c. shutdown mode the MAX6662 features a programmable shutdown mode. set the shutdown bit in the configuration register to 1 to shut down. in the shutdown mode, everything is disabled except the power-on reset (por) and the seri- al interface. in the shutdown mode, information stored in all registers is retained. the temperature register retains the temperature from the last conversion result. serial interface protocol the serial interface consists of three signal lines: chip select ( cs ), bidirectional data line (sio), and serial clock (sclk). only the master (external) drives cs and sclk. both the master and the MAX6662 drive sio. when cs is high, the MAX6662 does not respond to any activity on clock and data lines. when cs goes low, a transaction begins. a valid transaction has 24 clock cycles provided from sclk after cs goes lowno more and no fewer. any communication with more or fewer than exactly 24 clocks is ignored. data is clocked in to the MAX6662 at the rising edge of sclk when the mas- ter is writing. data is clocked out at the falling edge of sclk when the master is reading. both the command byte and data word are clocked in (or out) with the most-significant bit (msb) bit first. the first eight clock cycles are dedicated to the command byte (1 bit per cycle). this command byte is input to the MAX6662 through the sio. sixteen cycles of data follow. the 16 cycles of data are either driven by the master or by the MAX6662, depending on the command byte. if the MAX6662 is driving the sio, it starts driving at the falling edge of the eighth clock up until the rising edge of cs . data is available on the falling edge of the eighth clock cycle. figure 3 depicts a valid serial interface transaction and figure 4 is the serial interface timing diagram. 1234567 8 910 2324 data word (16 bits) cs sclk sio command byte (8 bits) figure 3. MAX6662 serial interface operation t ss t s t s t t t tr t ds t do t f s s sio t d figure 4. detailed serial interface timing diagram bit por description 15 to 13 0 reserved. writing to these bits is ignored. 12 0 fault queue bit. set to 1 to enable queue. 11 0 alert polarity bit. set to 1 for active-high alert output. default is 0 for the alert output active-low. 10 0 ot polarity bit. set to 1 for active-high ot output. default is 0 for the ot output active-low. 9 0 interrupt mode bit. set to 1 to enable the interrupt mode. default is 0 for the comparator mode. 8 0 shutdown bit. set to 1 to shut down the MAX6662. 7 to 0 0 reserved. writing to these bits is ignored. table 1. bit descriptions of the configuration register
MAX6662 12-bit + sign temperature sensor with spi-compatible serial interface _______________________________________________________________________________________ 7 the first bit of the command byte is always high to sig- nify a start, and the second bit is an r/ w bit, high for read and low for write. there are a total of 11 valid commands. the temperature conversion runs continu- ously and asynchronously from the serial interface. when the temperature register is read, any conversion in progress is aborted and the data output is from the previous conversion. a new conversion is started each time the serial interface is accessed. MAX6662 registers the MAX6662 has six registers: temperature, configura- tion, t hyst , t max , t low , and t high registers. they are all 16 bits (figure 5). the temperature register is read only; all other registers can be read from or written to. temperature register the msb of the temperature register is the sign bit. the next 12 bits are temperature data. the digital tempera- ture data for the most recent temperature conversion is temperature register (command = c1h) label 15 sign bit 14 data msb 13 12 11 10 9 8 7 6 5 4 3 data lsb 2 t over flag 1 t high flag 0 t low flag por state 0000000000000000 configuration register (command = c3h for reading; command = 83h for writing) label 15 * 14 * 13 * 12 fault queue 11 alert polarity 10 ot polarity 9 interrupt mode 8 shutdown mode 7 * 6 * 5 * 4 * 3 * 2 * 1 * 0 * por state 0 0 0 0 0 0 0 0 00000000 temperature limit registers (t hyst , t max , t low , t high ) (table 2) label 15 sign 14 data msb 13 12 11 10 9 8 7 data lsb 6 * 5 * 4 * 3 * 2 * 1 * 0 * por state ** * reserved (not used). writing to this bit is ignored. ** t hyst register: 0000 0001 0000 0000b (2c) ** t max register: 0010 1000 0000 0000b (+80c) ** t low register: 0000 0101 0000 0000b (+10c) ** t high register: 0010 0000 0000 0000b (+64c) figure 5. bit assignment for the MAX6662 registers command description c1h temperature register read c3h configuration register read c5h t hyst register read c7h t max register read c9h t low register read cbh t high register read 83h configuration register write 85h t hyst register write 87h t max register write 89h t low register write 8bh t high register write table 2. command codes for the temperature limit registers
stored in the temperature register and is in c, using a twos-complement format with 1lsb corresponding to 0.0625c (table 3). the three least-significant bits (lsbs) are temperature status (flag) bits. the temperature regis- ter is read only. set the command byte to c1h for reading the temperature register. configuration register the configuration register uses only 5 bits, bits 8 to 12. table 1 describes its function. bit 8 is the shutdown bit and should be set to 1 to shut down the entire MAX6662 except the serial interface and por. bit 12 is the fault queue bit. when the fault queue bit is 1, the alert and ot outputs are asserted if four consecutive temperature faults occurred. the configuration register can be read or written to. writing to unused bits is ignored. set the command byte to c3h for reading from this register; set the command byte to 83h for writing to this register. temperature-limit registers the high-temperature (t high ), low-temperature (t low ), and the hysteresis (t hyst ) registers set the temperature limit for triggering the alert (figure 1). the maximum-temperature (t max ) and hysteresis reg- isters set the temperature threshold for the ot output. these temperature-limit registers use the 9msb bits (8 bits + sign) for setting temperature values in twos complement format with 1c resolution. the 7lsbs are ignored. these registers can be read or written to. table 2 shows the command bytes for reading and writing to these registers. applications information the MAX6662 supply current is typically 125a when the serial interface is active. when driving high-imped- ance loads, the devices dissipate negligible power; therefore, the die temperature is essentially the same as the package temperature. the key to accurate tem- perature monitoring is good thermal contact between the MAX6662 package and the monitored device or cir- cuit. heat flows in and out of plastic packages primarily through the leads. short, wide copper traces leading to the temperature monitor ensure that heat transfers quickly and reliably. the rise in die temperature due to self-heating is given by the following formula: ? t j = p dissipation x ja where p dissipation is the power dissipated by the MAX6662, and ja is the packages thermal resistance. the typical thermal resistance is +170c/w for the 8-pin so package. to limit the effects of self-heating, minimize the output currents. for example, if the MAX6662 sinks 4ma with the maximum alert voltage specification of 0.8v, an additional 3.2mw of power is dissipated within the ic. this corresponds to a 0.54c rise in the die temperature. chip information transistor count: bipolar: 182 mos: 10177 process: bicmos MAX6662 12-bit + sign temperature sensor with spi-compatible serial interface 8 _______________________________________________________________________________________ temperature ( c) binary code +150.0000 0100 1011 0000 0xxx +125.0000 0011 1110 1000 0xxx +25.0000 0000 1100 1000 0xxx +0.0625 0000 0000 0000 1xxx 0.0000 0000 0000 0000 0xxx -0.0625 1111 1111 1111 1xxx -25.0000 1111 0011 0111 0xxx -55.0000 1111 1100 0111 0xxx table 3. output code vs. temperature
MAX6662 12-bit + sign temperature sensor with spi-compatible serial interface maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it 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 _____________________ 9 ? 2001 maxim integrated products printed usa is a registered trademark of maxim integrated products. package information soicn.eps
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