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ANALOG DEVICES ADT7320 handbook

1. 3 0V 1SPS 0 4 100 50 0 50 100 150 200 8 2 5 3 0 3 5 4 0 45 5 0 5 5 6 0 5 TEMPERATURE C 8 SUPPLY VOLTAGE V 8 Figure 6 Operating Supply Current vs Temperature Figure 9 Shutdown Current vs Supply Voltage Rev PrD Page 9 of 26 ADT7320 IT TAKES LESS THAN 2 SECONDS FOR THE DUT TO REACH 63 2 OF ITS FINAL TEMPERATURE SPAN DUT TEMPERATURE C 09012 110 TIME s Figure 10 Thermal Response Time Rev PrD Page 10 of 26 THEORY OF OPERATION CIRCUIT INFORMATION The ADT7320 is a high accuracy digital temperature sensor that uses a 16 bit ADC to monitor and digitize the temperature to a resolution of 0 0078 C By default the ADC resolution is set to 13 bits 0 0625 C An internal temperature sensor generates a voltage proportional to absolute temperature this voltage is compared to an internal voltage reference and input into a precision digital modulator The internal temperature sensor has high accuracy and linearity over the entire rated temperature range without the need for correction or calibration by the user The sensor output is digitized by a sigma delta modulator also known as the charge balance type ADC This type of converter uses time domain oversampling and a high accuracy comparator to deliver 16 bits of resolution in an extremely compact circuit CONVERTER DETAILS The 2 A modulator consists of an input sampler a summing network an integrator a compara
2. 09012 003 Figure 3 Pin Configuration Table 4 Pin Function Descriptions Pin No Mnemonic Description 1 SCLK Serial Clock Input The serial clock is used to clock data into and out of any register of the ADT7320 2 DOUT Serial Data Output Data is clocked out on the SCLK falling edge and is valid on the SCLK rising edge 3 DIN Serial Data Input Serial data to be loaded to the control registers of the part is provided on this input Data is clocked into the registers on the rising edge of SCLK 4 cs Chip Select Input The device is enabled when this input is low The device is disabled when this pin is high 5 NC No Connect Do not connect to this pin The NC pin is not bonded to the die internally 6 NC No Connect Do not connect to this pin The NC pin is not bonded to the die internally 7 NC No Connect Do not connect to this pin The NC pin is not bonded to the die internally 8 NC No Connect Do not connect to this pin The NC pin is not bonded to the die internally 9 INT Overtemperature and Undertemperature Interrupt Logic output Power up default setting is as an active low comparator interrupt Open drain configuration A pull up resistor is required typically 10 kQ 10 CT Critical Overtemperature Interrupt Logic output Power up default polarity is active low Open drain configuration A pull up resistor is required typically 10 kQ 11 GND Analog and Digital Ground 12 Vop Positive Supply Voltage 2 7 V to 5 5 V
3. Decouple the supply with a 0 1 ceramic capacitor to GND 13 NC No Connect Do not connect to this pin The NC pin is not bonded to the die internally 14 NC No Connect Do not connect to this pin The NC pin is not bonded to the die internally 15 NC No Connect Do not connect to this pin The NC pin is not bonded to the die internally 16 NC No Connect Do not connect to this pin The NC pin is not bonded to the die internally 17 EPAD Exposed Pad To ensure correct operation the exposed pad should either be left floating or connected to ground Rev PrD Page 8 of 26 ADT7320 TYPICAL PERFORMANCE CHARACTERISTICS 5 5 g 8 z E 8 a 7 60 40 20 20 40 60 80 100 120 140 lt 100 50 0 50 100 150 200 8 TEMPERATURE C 8 TEMPERATURE C 8 Figure 4 Temperature Accuracy at 3 V Figure 7 Shutdown Current vs Temperature E MAX ACCURACY LIMITS c tc ui 8 lt a m 00 g 2 60 40 20 0 20 40 60 80 100 120 140 amp 2 5 3 0 3 5 4 0 45 5 0 5 5 60 8 TEMPERATURE C 8 SUPPLY VOLTAGE V 8 Figure 5 Temperature Accuracy at 5 V Figure 8 Average Operating Supply Current vs Supply Voltage 300 Ee 250 E CONTINUOUS 200 VERSION 5 a 150 8 5 5 100 o 5 5V 1SPS X 7 1 50
4. 0 15 C This 3 o specification is provided to enable comparison with other vendors who use these limits 3 For higher accuracy at 5 V operation contact Analog Devices Inc Based on a floating average of 10 readings 5 Drift includes solder heat resistance and lifetime test performed as per JEDEC Standard JESD22 A108 SPI TIMING SPECIFICATIONS 40 C to 150 C Vpp 2 7 V to 5 5 V unless otherwise noted All input signals are specified with rise time tr fall time tr 5 ns 1096 to 9096 of Vpp and timed from a voltage level of 1 6 V Table 2 Parameter Limit at Tmax Unit Descriptions ti 0 ns min CS falling edge to SCLK active edge setup time t 100 ns min SCLK high pulse width ts 100 ns min SCLK low pulse width ta 30 ns min Data setup time prior to SCLK rising edge ts 25 ns min Data hold time after SCLK rising edge 16 5 ns min Data access time after SCLK falling edge 60 ns max Voo 4 5 to 5 5V 80 ns max Voo 2 7 V to 3 6V t 10 ns min Bus relinquish time after CS inactive edge 80 ns max Bus relinquish time after CS inactive edge ts 0 ns min SCLK inactive edge to CS rising edge hold time to 0 ns min CS falling edge to DOUT active time 60 ns max Voo 4 5 V to 5 5V 80 ns max Voo 2 7 V to 3 6V tio 10 ns min SCLK inactive edge to DOUT low Sample tested during initial release to ensure compliance See Error Reference source not found 3 This means that the times quoted in the timi
5. 2 Low power consumption 3 Excellent long term stability and reliability 4 High accuracy for industrial instrumentation and medical applications 5 Packaged in a 16 lead RoHS compliant 4 mm x 4 mm LFCSP package One Technology Way P O Box 9106 Norwood MA 02062 9106 U S A Tel 781 329 4700 www analog com Fax 781 461 3113 2011 Analog Devices Inc All rights reserved ADT7320 TEMPERATURE VALUE REGISTER CONFIGURATION REGISTER REGISTER THIGH REGISTER SPI INTERFACE FUNCTIONAL BLOCK DIAGRAM TLow INTERNAL REGISTER OSCILLATOR INTERNAL Tuer REFERENCE REGISTER STATUS REGISTER TEMPERATURE Z A SENSOR CmoptitaTor ID FILTER LOGIC REGISTER Figure 1 Rev PrD Page 2 of 26 ADT7320 09012 001 TABLE OF CONTENTS Uc c Applications ix ee tl ette times General Descriptions cep gere pof eret iE Product Highlights e n Functional Block Diagram eerte Revision History tete net eret ee o eet Lupin SDeCIfICatlODS Leere pti etta eee toa det ete te ges SPI Timing Specifications seen Absolute Maximum Ratings eerte ESD Gautioft tete eae estem Mna Pin Configuration and Function Descriptions Typical Performance Characteristics sss Theory of Operation essere tete tentnnennennent Circuit Information sen aer ior a EE E tete entente Converter Deta
6. C 143 C 142 C 141 C 140 C CT PIN POLARITY ACTIVE LOW CT PIN POLARITY ACTIVE HIGH WRITE TO BIT 5 AND BIT 6 OF CONFIGURATION REGISTER THERE IS A 240ms DELAY BETWEEN WRITING TO THE CONFIGURATION REGISTER TO START A STANDARD ONE SHOT CONVERSION AND THE CT PIN GOING ACTIVE THIS IS DUE TO THE CONVERSION TIME THE DELAY IS 60ms IN THE CASE OF A ONE SHOT CONVERSION BIT 5 AND BIT 6 OF CONFIGURATION REGISTER Tcnir WRITE BIT 5 AND BIT 6 OF CONFIGURATION REGISTER 09012 013 Figure 13 One Shot CT Pin ONE SHOT MODE When one shot mode is enabled the ADT7320 immediately completes a conversion and then goes into shutdown mode The one shot mode is useful when one of the circuit design priorities is to reduce power consumption To enable one shot mode set Bits 6 5 of the configuration register Register Address 0x01 to 01 After writing to the operation mode bits wait for at least 240 ms before reading back the temperature from the temperature value register This delay ensures that the ADT7320 has adequate time to power up and complete a conversion To obtain an updated temperature conversion reset Bits 6 5 of the configuration register Register Address 0x01 to 01 CT and INT Operation in One Shot Mode See Figure 13 for more information on one shot CT pin operation for Tcrrr overtemperature events when one of the limits is exceeded Note t
7. INT pin is reset it becomes active again only when the temperature is greater than the temperature stored in the setpoint register or less than the temperature stored in the Trow setpoint register Placing the ADT7320 into shutdown mode resets the INT pin in interrupt mode TIME 09012 020 READ READ Figure 19 INT Output Temperature Response for Tuas Overtemperature Events Rev PrD Page 22 of 26 TEMPERATURE INT PIN COMPARATOR MODE POLARITY ACTIVE LOW INT PIN INTERRUPT MODE POLARITY ACTIVE LOW INT PIN COMPARATOR MODE POLARITY ACTIVE HIGH INT PIN INTERRUPT MODE POLARITY ACTIVE HIGH Figure 20 INT Output Temperature Response for Tiow Undertemperature Events READ READ Rev PrD Page 23 of 26 READ TLow Tuvsr TIME 09012 021 ADT7320 ADT7320 APPLICATIONS INFORMATION THERMAL RESPONSE TIME Thermal response is a function of the thermal mass of the temperature sensor but it is also heavily influenced by the mass of the object that the IC is mounted to For example a large PCB containing large amounts of copper tracing can act as a large heat sink and slow the thermal response For a faster thermal response it is recommended that the sensor be mounted on a PCB that is as small as possible Figure 10 shows the typical response time of less than 2 seconds to reach 63 2 of the temperature span of the DUT The temperature values are th
8. conditions above those indicated in the operational section of this specification is not implied Exposure to absolute maximum rating conditions for extended periods may affect device reliability ESD CAUTION ESD electrostatic discharge sensitive device Charged devices and circuit boards can discharge without detection Although this product features patented or proprietary protection circuitry damage dy A may occur on devices subjected to high energy ESD Therefore proper ESD precautions should be taken to avoid performance degradation or loss of functionality 1 Sustained operation above 125 C results in a shorter product lifetime For more information contact an Analog Devices Inc sales representative 2 Values relate to package being used on a standard 2 layer PCB This gives worst case and 3T ambient temperature 4 Junction to case resistance is applicable to components featuring a preferential flow direction for example components mounted on a heat sink Junction to ambient resistance is more useful for air cooled PCB mounted components Rev PrD Page 7 of 26 ADT7320 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS ADT7320 TOP VIEW Not to Scale NOTES 1 NC NO CONNECT DO NOT CONNECT TO THIS PIN THE NC PIN IS NOT BONDED TO THE DIE INTERNALLY 2 TO ENSURE CORRECT OPERATION THE EXPOSED PAD SHOULD EITHER BE LEFT FLOATING OR CONNECTED TO GROUND
9. operated with CS used as a frame synchronization signal This setup is useful for DSP interfaces In this case the first bit MSB is effectively clocked out by CS because CS normally occurs after the falling edge of SCLK in DSPs SCLK can continue to run between data transfers provided that the timing values are obeyed CS can be tied to ground and the serial interface can operate in a 3 wire mode DIN DOUT and SCLK are used to communicate with the ADT7320 in this mode For microcontroller interfaces it is recommended that SCLK idle high between data transfers SERIAL INTERFACE RESET The serial interface can be reset by writing a series of 1s on the DIN input If a Logic 1 is written to the ADT7320 DIN line for at least 32 serial clock cycles the serial interface is reset This ensures that the interface can be reset to a known state if the interface is lost due to a software error or a glitch in the system A reset returns the interface to the state in which it expects a write to a communications register This operation resets the contents of all registers to their power on values Following a reset allow a period of 500 us before addressing the serial interface Rev PrD Page 21 of 26 ADT7320 INT AND CT OUTPUTS The INT and CT pins are open drain outputs and both pins require 10 pull up resistor to The ADT7320 must be fully powered up to before reading INT and CT data UNDERTEMPERATURE AND OVER
10. 000 150 C 0 1001 0110 0000 TEMPERATURE CONVERSION FORMULAS 16 Bit Temperature Data Format Positive Temperature ADC Code dec 128 Negative Temperature ADC Code dec 65 536 128 where ADC Code uses all 16 bits of the data byte including the sign bit Negative Temperature ADC Code dec 32 768 128 where the MSB is removed from the ADC code 13 Bit Temperature Data Format Positive Temperature ADC Code dec 16 Negative Temperature ADC Code dec 8192 16 where ADC Code uses all 13 bits of the data byte including the sign bit Negative Temperature ADC Code dec 4096 16 where the MSB is removed from the ADC code 10 Bit Temperature Data Format Positive Temperature ADC Code dec 2 Negative Temperature ADC Code dec 1024 2 where ADC Code uses all 10 bits of the data byte including the sign bit Negative Temperature ADC Code dec 512 2 where the MSB is removed from the ADC Code 9 Bit Temperature Data Format Positive Temperature ADC Code dec Negative Temperature ADC Code dec 512 where ADC Code uses all nine bits of the data byte including the sign bit Negative Temperature ADC Code dec 256 where the MSB is removed from the ADC Code Rev PrD Page 14 of 26 REGISTERS The ADT7320 contains eight registers e status register e configuration register e Five temperature registers AnID register The status register
11. ANALOG DEVICES 0 25 C Accurate 16 Bit Digital SPI Temperature Sensor ADT7320 FEATURES High performance Temperature accuracy 0 20 C from 10 C to 85 C at 3 0 V to 3 3V 0 25 from 20 C to 105 C at 3 0 V to 3 6 V 16 bit temperature resolution 0 0078 C Ultralow temperature drift 0 0073 C NIST traceable or equivalent Fast first temperature conversion on power up of 6 ms Easy implementation No temperature calibration correction required by user No linearity correction required Low power Power saving 1 sample per second SPS mode 700 pW typical at 3 3 V in normal mode 7 pW typical at 3 3 V in shutdown mode Wide operating ranges Temperature range 40 C to 150 C Voltage range 2 7 V to 5 5 V Programmable interrupts Critical overtemperature interrupt Overtemperature undertemperature interrupt SPI compatible interface 16 lead RoHS compliant 4 mm x 4 mm LFCSP package APPLICATIONS RTD and thermistor replacement Thermocouple cold junction compensation Medical equipment Industrial control and test Food transportation and storage Environmental monitoring and HVAC Laser diode temperature control Rev PrD Information fumished by Analog Devices is believed to be accurate and reliable However no responsibility is assumed by Analog Devices for its use nor for any infringements of patents or other rights of third parties that may result fromits use Specifications subject to change without notice No license
12. TEMPERATURE DETECTION The INT and CT pins have two undertemperature overtemperature modes comparator mode and interrupt mode The interrupt mode is the default power up overtemperature mode The INT output pin becomes active when the temperature is greater than the temperature stored the setpoint register or less than the temperature stored in the Tiow setpoint register How this pin reacts after an undertemperature or overtemperature event depends on the overtemperature mode selected Figure 19 illustrates the comparator and interrupt modes for events exceeding the limit with both pin polarity settings Figure 20 illustrates the comparator and interrupt modes for events exceeding the Tiow limit with both pin polarity settings TEMPERATURE 82 C 81 C 80 C 79 C 78 C 77 C 76 C 75 C 74 C 73 C INT PIN COMPARATOR MODE POLARITY ACTIVE LOW INT PIN INTERRUPT MODE POLARITY ACTIVE LOW INT PIN COMPARATOR MODE POLARITY ACTIVE HIGH INT PIN INTERRUPT MODE POLARITY ACTIVE HIGH READ Comparator Mode In comparator mode the INT pin returns to its inactive status when the temperature drops below the Tuvsr limit or rises above the Tiow Tuysr limit Placing the ADT7320 into shutdown mode does not reset the INT state in comparator mode Interrupt Mode In interrupt mode the INT pin returns to its inactive status when any ADT7320 register is read When the
13. bit resolution 1 flag LSB1 Flags a event if the configuration register Register Address 0x01 7 0 13 bit resolution When the temperature value is above this bit is set to 1 Contains Least Significant Bit 1 of the 15 bit temperature value when the configuration register Register Address 0x01 7 1 16 bit resolution 2 Terr flag LSB2 Flags Terr event if the configuration register Register Address 0x01 7 0 13 bit resolution When the temperature value exceeds Terr this bit is set to 1 Contains the Least Significant Bit 2 of the 15 bit temperature value if the configuration register Register Address 0x01 7 1 16 bit resolution 7 3 00000 Temp Temperature value in twos complement format 14 8 0000000 Temp Temperature value in twos complement format 15 0 Sign Sign bit indicates if the temperature value is negative or positive Table 10 ID Register Register Address 0x03 Bit s Default Value Type Name Description 2 0 011 R Revision ID Contains the silicon revision identification number 7 3 11000 R Manufacturer ID Contains the manufacturer identification number Table 11 Setpoint Register Register Address 0x04 Bit s Default Value Type Name Description 15 0 0x4980 R W 16 bit critical overtemperature limit stored
14. e digital bytes read back through the digital interface The response time includes all delays incurred on chip during signal processing SUPPLY DECOUPLING The ADT7320 must have a decoupling capacitor connected between and GND otherwise incorrect temperature readings will be obtained A 0 1 uF decoupling capacitor such as a high frequency ceramic type must be used and mounted as close as possible to the pin of the ADT7320 If possible the ADT7320 should be powered directly from the system power supply This arrangement shown in Figure 21 isolates the analog section from the logic switching transients Even if a separate power supply trace is not available generous supply bypassing reduces supply line induced errors Local supply bypassing consisting of a 0 1 uF ceramic capacitor is critical for the temperature accuracy specifications to be ADT7320 achieved TTL CMOS LOGIC CIRCUITS POWER SUPPLY Figure 21 Use of Separate Traces to Reduce Power Supply Noise 09012 022 POWERING FROM A SWITCHING REGULATOR Precision analog devices such as the ADT7320 require a well filtered power source If the ADT7320 is powered from a switching regulator noise may be generated above 50 kHz that may affect the temperature accuracy specifications To prevent this an RC filter should be used between the power supply and ADT7320 Von The value of the components used should be carefully considered to ensure that
15. en when it is in shutdown mode ADT7320 When the part is taken out of shutdown mode the internal clock restarts and a conversion is initiated FAULT QUEUE Bit 0 and Bit 1 of the configuration register Register Address 0x01 are used to set up a fault queue Up to four faults are provided to prevent false tripping of the INT and CT pins when the ADT7320 is used in a noisy temperature environment The number of faults set in the queue must occur consecutively to set the INT and CT outputs For example if the number of faults set in the queue is four then four consecutive temperature conversions must occur with each result exceeding a temperature limit set in any of the limit registers before the INT and CT pins are activated If two consecutive temperature conversions exceed a temperature limit and the third conversion does not the fault count is reset to zero Rev PrD Page 13 of 26 ADT7320 TEMPERATURE DATA FORMAT One LSB of the ADC corresponds to 0 0625 C in 13 bit mode or 0 0078 C in 16 bit mode The ADC can theoretically measure a temperature range of 255 C but the ADT7320 is guaranteed to measure low value temperature limit of 40 C to a high value temperature limit of 150 C The temperature measurement result is stored in the 16 bit temperature value register and is compared with the high temperature limits stored in the Tcur setpoint register and the setpoint register It is also compared with the
16. ent occurs The temperature is stored in twos complement format with the MSB being the temperature sign bit The default setting for the Tiow setpoint is 10 C Bit s Default Value Type Name Description 3 0 0101 RAW Tuyst Hysteresis value from 0 C to 15 C Stored in straight binary format The default setting is 5 C 7 4 0000 R W N A N A not applicable Not used Table 13 Setpoint Register Register Address 0x06 Bit s Default Value Type Name Description 15 0 0x2000 R W Trick 16 bit overtemperature limit stored in twos complement format Table 14 Tiow Setpoint Register Register Address 0x07 Bit s Default Value Type Name Description 15 0 0x0500 R W Tiow 16 bit undertemperature limit stored in twos complement format Rev PrD Page 18 of 26 SERIAL INTERFACE MICROCONTROLLER ADT7320 PULL UP Vpp TO Vpp Vpp ADT7320 09012 014 Figure 14 Typical SPI Interface Connection The ADT7320 has a 4 wire serial peripheral interface SPI The interface has a data input pin DIN for writing data to the device a data output pin DOUT for reading data back from the device and a serial data clock pin SCLK for clocking data into and out of the device A chip select pin CS enables or disables the serial interface CS is required for correct operation of the interface Data is clocked out
17. f their respective owners www ana 0 g com PR09012 0 11 11 PrD DEVICES Rev PrD Page 26 of 26
18. face In continuous conversion mode the read operation provides the most recent converted result On power up the first conversion is a fast conversion taking typically 6 ms If the temperature exceeds 147 C the CT pin is asserted low If the temperature exceeds 64 C the INT pin is asserted low Fast conversion temperature accuracy is typically within 5 C The conversion clock for the part is generated internally No external clock is required except when reading from and writing to the serial port The measured temperature value is compared with a critical temperature limit stored in the 16 bit Tcrir setpoint register a high temperature limit stored the 16 bit setpoint register and low temperature limit stored in the 16 bit setpoint register If the measured value exceeds the high or low temperature limits the INT pin is activated if it exceeds the Tcrrr limit the CT pin is activated The polarity of the INT and CT pins is programmable for via the configuration register and the INT and CT pins are also programmable for interrupt mode via the configuration register Rev PrD Page 11 of 26 ADT7320 DIN 0x08 X 0x20 WAIT 240ms MINIMUM FOR CONVERSION TO FINISH DOUT Tht 09012 300 Figure 12 Typical SPI One Shot Write to Configuration Register Followed by a Read from the Temperature Value Register TEMPERATURE 149 C 148 C 147 C 146 C 145 C 144
19. hat in interrupt mode a read from any register resets the INT and CT pins For the INT pin in comparator mode if the temperature drops below the value or goes above the Trow value a write to the operation mode bits Bit 5 and Bit 6 of the configuration register Register Address 0x01 resets the INT pin For the CT pin in comparator mode if the temperature drops below the Tcur Tuvsr value a write to the operation mode bits Bit 5 and Bit 6 of the configuration register Register Address 0x01 resets the CT pin see Figure 13 Rev PrD Page 12 of 26 When using one shot mode ensure that the refresh rate is appropriate to the application being used 1SPS MODE In 1 SPS mode the part performs one measurement per second A conversion takes 60 ms typically and the part remains in the idle state for the remaining 940 ms period This mode is enabled by setting Bits 6 5 of the configuration register Register Address 0x01 to 10 SHUTDOWN MODE The ADT7320 can be placed in shutdown mode by setting Bits 6 5 of the configuration register Register Address 0x01 to 11 The ADT7320 can be taken out of shutdown mode by setting Bits 6 5 of the configuration register Register Address 0x01 to 00 The ADT7320 typically takes 1 ms with a 0 1 uF decoupling capacitor to come out of shut down mode The conversion result from the last conversion prior to shutdown can still be read from the ADT7320 ev
20. ian Register Address 0x06 and Tiow Register Address 0x07 Compare these values with the specified defaults in Table 6 If all the readings match the interface is operational 4 Write to the configuration register to set the ADT7320 to the desired configuration Read the temperature value register It should produce a valid temperature measurement Rev PrD Page 24 of 26 OUTLINE DIMENSIONS ADT7320 PIN 1 PIN 1 INDICATOR INDICATOR 2 70 2 60 SQ 2 50 t 0 45 __ 2 0 20 MIN 0 40 BOTTOM VIEW 0 35 0 80 FOR PROPER CONNECTION OF 0 75 THE EXPOSED PAD REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS n COPLANARITY SECTION OF THIS DATA SHEET SEATING E d 0 08 PLANE 0 20 REF COMPLIANT STANDARDS MO 220 WGGC 8 Figure 22 16 Lead Lead Frame Chip Scale Package LFCSP 4mm x 4 mm Body Very Very Thin Quad CP 16 17 Dimensions shown in millimeters ORDERING GUIDE Model Temperature Range Package Description Package Option ADT7320UCPZ R2 40 C to 150 C 16 lead LFCSP_WQ CP 16 17 ADT7320UCPZ RL7 40 C to 150 C 16 Lead LFCSP_WQ CP 16 17 EVAL ADT7X20EBZ Evaluation Board 12 RoHS Compliant Part Operating at extended temperatures over prolonged periods may shorten the lifetime performance of the part Rev PrD Page 25 of 26 ADT7320 NOTES 2011 Analog Devices Inc All rights reserved Trademarks and ANALOG registered trademarks are the property o
21. iii P yet RR 25 Ordering Guide eee eme ides 25 Rev PrD Page 3 of 26 ADT7320 SPECIFICATIONS 40 C to 125 C Vpp 2 7 V to 5 5 V unless otherwise noted Table 1 Parameter Min Typ Max Unit Test Conditions Comments TEMPERATURE SENSOR AND ADC Accuracy 0 0017 0 207 C 10 to 85 C Voo 3 0 V to 3 3V 0 25 C Ta 20 to 105 C 3 0 V to 3 6 V 0 25 20 C to 85 C Voo 2 7 V 0 30 C 40 C to 105 C Voo 3 0 V 0 35 C 40 C to 105 C 2 7 V to 3 3 V 0 50 40 C to 125 C 3 0V to 3 6V 0 503 C 10 C to 105 C Von 4 5 V to 5 5 V 0 65 C 40 C to 125 C Von 4 5 V to 5 5 V 0 85 C Ta 150 Voo 4 5 V to 5 5 V 1 0 C Ta 150 C Voo 2 7 V to 3 6 V ADC Resolution 13 Bits Twos complement temperature value of sign bit plus 12 ADC bits power up default resolution 16 Bits Twos complement temperature value of sign bit plus 15 ADC bits Bit 7 1 in the configuration register Temperature Resolution 13 Bit 0 0625 C 13 bit resolution sign 12 bits 16 Bit 0 0078 16 bit resolution sign 15 bits Temperature Conversion Time 240 ms Continuous conversion and one shot conversion mode Fast Temperature Conversion Time 6 ms First conversion on power up only 1 SPS Conversion Time 60 ms Conversion time for 1 SPS mode Temperature Hystere
22. ils erit ee a Temperature Data Format sse Temperature Conversion Formulas eee Repi STETS 2225 22 sa Status REVISION HISTORY 11 11 Revision Pr D Preliminary Version ADT7320 Configuration Register essent 16 Temperature Value Register sete 17 TD RES iS 17 Tour Setpoint Register 17 Setpoint Register seen 18 Setpoint Register ssseeeeeneeten 18 Trow Setpoint Register eite 18 Serial Interface eet ERR RHEIN 19 SPI Command Byte seeeee tete 19 Writing eerte e RI Iu hans 20 Reading Dat i teer tp Uri dee n 21 Interfacing to DSPs or Microcontrollers 21 Serial Interface Reset triti eed 21 INTand CT Outputs cte ehe 22 Undertemperature and Overtemperature Detection 22 Applications Information esent 24 Thermal Response Time seen 24 Supply Decoupling 24 Powering from a Switching Regulator 24 Temperature 24 Quick Guide to Measuring 24 Outline Dimensions e
23. ine transaction The ADT7320 clocks the data into the register addressed in the command byte on the rising edge of SCLK The master finishes the write transaction by pulling CS high 1 1 1 1 8 BIT COMMAND BYTE i d 1 1 0 RAW REGISTER ADDR 0 DIN 09012 128 SCLK 1 1 1 1 8 BIT COMMAND BYTE 1 1 0 RW REGISTER ADDR 0 1 1 1 DIN 9 Figure 16 Writing to a 16 Bit Register Rev PrD Page 20 of 26 8 BIT COMMAND BYTE r 1 1 1 1 1 I 1 i h 0 RAW REGISTER ADDR 0 1 0 i 1 1 1 LI DIN 1 1 4 1 8 BIT COMMAND BYTE 8 DATA _______ gt con A SX XXX XN Figure 17 Reading from an 8 Bit Register ADT7320 09012 030 pour NOD OND OOOE KEK I 1 1 1 1 1 1 1 16 DATA 09012 031 Figure 18 Reading from a 16 Bit Register READING DATA A read transaction begins when the master writes the command byte to the ADT7320 with the read write bit set to 1 The master then supplies 8 or 16 clock pulses depending on the addressed register and the ADT7320 clocks out data from the addressed register on the DOUT line Data is clocked out on the first falling edge of SCLK following the command byte The read transaction finishes when the master pulls CS high INTERFACING TO DSPs OR MICROCONTROLLERS The ADT7320 can be
24. is granted by implication or otherwise under any patent or patent rights of Analog Devices Trademarks and registered trademarks are the property of their respective owners GENERAL DESCRIPTION The ADT7320 is a high accuracy digital temperature sensor that offers breakthrough performance over a wide industrial temperature range housed in a 4 mm x 4 mm LFCSP package It contains an internal band gap reference a temperature sensor and a 16 bit analog to digital converter ADC to monitor and digitize the temperature to a resolution of 0 0078 C The ADC resolution by default is set to 13 bits 0 0625 C The ADC resolution is a user programmable mode that can be changed through the serial interface The ADT7320 is guaranteed to operate over supply voltages from 2 7 V to 5 5 V Operating at 3 3 V the average supply current is typically 210 uA The ADT7320 has a shutdown mode that powers down the device and offers a shutdown current of typically 2 0 at 3 3 V The ADT7320 is rated for operation over the 40 C to 150 C temperature range The CT pin is an open drain output that becomes active when the temperature exceeds a programmable critical temperature limit The INT pin is also an open drain output that becomes active when the temperature exceeds a programmable limit The INT pin and CT pin can operate in either comparator or interrupt mode PRODUCT HIGHLIGHTS 1 Ease of use no calibration or correction required by the user
25. isters 5 0 R This bit is set to 1 when the temperature rises above the Tuich temperature limit This bit is cleared to 0 when the status register is read and or when the temperature measured drops below the limit set in the Tryst Setpoint registers 6 0 R Tert This bit is set to 1 when the temperature rises above the temperature limit This bit is cleared to 0 when the status register is read and or when the temperature measured drops below the limit set in the Terr Tuvsr setpoint registers 7 1 R RDY This bit goes low when the temperature conversion result is written to the temperature value register It is reset to 1 when the temperature value register is read In one shot and 1 SPS modes this bit is reset after a write to the operation mode bits in the configuration register Rev PrD Page 15 of 26 ADT7320 CONFIGURATION REGISTER This 8 bit read write register Register Address 0x01 stores various configuration modes for the ADT7320 including shutdown overtemperature and undertemperature interrupts one shot continuous conversion interrupt pin polarity and overtemperature fault queues Table 8 Configuration Register Register Address 0x01 Default Bit s Value Type Name Description 1 0 00 R W Fault queue These two bits set the number of undertemperature overtemperature faults that can occur before setting the INT and CT pins This helps to a
26. low temperature limit stored in the Tiow setpoint register Temperature data in the temperature value register the Tcur setpoint register the setpoint register and the Tiow setpoint register are represented by a 13 bit twos complement word The MSB is the temperature sign bit On power up the three LSBs Bit 0 to Bit 2 are not part of the temperature conversion result and are flag bits for Tcrir and Table 5 shows the 13 bit temperature data format without Bit 0 to Bit 2 The number of bits in the temperature data word can be extended to 16 bits twos complement by setting Bit 7 to 1 in the configuration register Register Address 0x01 When using a 16 bit temperature data value Bit 0 to Bit 2 are not used as flag bits and are instead the LSB bits of the temperature value The power on default setting has a 13 bit temperature data value Reading back the temperature from the temperature value register requires a 2 byte read Designers that use a 9 bit temperature data format can still use the ADT7320 by ignoring the last four LSBs of the 13 bit temperature value These four LSBs are Bit 3 to Bit 6 in Table 5 Table 5 13 Bit Temperature Data Format Temperature Digital Output Binary Bits 15 3 40 C 1 1101 1000 0000 25 C 111100111 0000 0 0625 C 11111 1111 1111 0 0 0000 0000 0000 0 0625 C 0 0000 0000 0001 25 C 0 0001 1001 0000 105 C 00110 1001 0000 125 00111 1101 0
27. ng characteristics in Table 2 are the true bus relinquish times of the part and as such are independent of external bus loading capacitances Rev PrD Page 5 of 26 ADT7320 SCLK DIN ty DOUT Lu 09012 002 Figure 2 Detailed SPI Timing Diagram Rev PrD Page 6 of 26 ABSOLUTE MAXIMUM RATINGS Table 3 Parameter Rating Voo to GND 0 3 V to 7 V DIN Input Voltage to GND 0 3 V to Voo 0 3 V DOUT Voltage to GND 0 3 V to Voo 0 3 V SCLK Input Voltage to GND CS Input Voltage to GND CT and INT Output Voltage to GND ESD Rating Human Body Model Operating Temperature Range Storage Temperature Range Maximum Junction Temperature Tmax Power Dissipation 16 Lead LFCSP Thermal Impedance Junction to Ambient Still Air Junction to Case IR Reflow Soldering Peak Temperature RoHS Compliant Package Time at Peak Temperature Ramp Up Rate Ramp Down Rate Time from 25 C to Peak Temperature 0 3 V to Voo 0 3 V 0 3 V to Voo 0 3 V 0 3 V to Voo 0 3 V 2 0 kV 40 C to 150 C 65 C to 160 C 150 C Wmax Timax 37 C W 33 C W 220 C 260 C 0 C 5 C 20 sec to 40 sec 3 C sec maximum 6 C sec maximum 8 minutes maximum ADT7320 Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device This is a stress rating only functional operation of the device at these or any other
28. of the ADT7320 on the falling edge of SCLK and data is clocked into the device on the rising edge of SCLK SPI COMMAND BYTE All data transactions on the bus begin with the master taking CS from high to low and sending out the command byte The command byte indicates to the ADT7320 whether the transaction is a read or a write and provides the address of the register for the data transfer Table 15 shows the command byte Table 15 Command Byte C7 C6 C5 C4 2 C1 0 R W Register address 0 0 0 Bit C7 Bit C2 Bit C1 and Bit CO of the command byte must all be set to 0 to successfully begin a bus transaction The SPI interface does not work correctly if a 1 is written into any of these bits Bit C6 is the read write bit 1 indicates a read and 0 indicates a write Bits C5 C3 contain the target register address One register can be read from or written to per bus transaction Rev PrD Page 19 of 26 ADT7320 WRITING DATA Figure 15 shows a write to an 8 bit register and Figure 16 shows a write to a 16 bit register Data is written to the ADT7320 in 8 bits or 16 bits depending on the addressed register The first byte written to the device is the The master must begin a new write transaction on the bus for command byte with the read write bit set to 0 The master every register write Only one register is written to per bus then supplies the 8 bit or 16 bit input data on the DIN l
29. r Address 0x02 as a 16 bit value Bit 2 Bit 1 and Bit 0 are event alarm flags for Tcur and Tiow respectively When the ADC is configured to convert the temperature to a 16 bit digital value Bit 2 Bit 1 and Bit 0 are no longer used as flag bits and are instead used as the LSB bits for ADT7320 ID REGISTER This 8 bit read only register Register Address 0x03 stores the manufacturer ID in Bit 7 to Bit 3 and the silicon revision in Bit 2 to Bit 0 Tcrr SETPOINT REGISTER The 16 bit Tcrrr setpoint register Register Address 0x04 stores the critical overtemperature limit value A critical overtemperature event occurs when the temperature value stored in the temperature value register exceeds the value stored in this register The CT pin is activated if a critical overtemperature event occurs The the extended digital value temperature is stored in twos complement format with the MSB being the temperature sign bit The default setting for the Tcur setpoint is 147 C Table 9 Temperature Value Register Register Address 0x02 Bit s Default Value Type Name Description 0 0 R Tow flag LSBO Flags a Tiow event if the configuration register Register Address 0x01 7 0 13 bit resolution When the temperature value is below this bit is set to 1 Contains Least Significant Bit 0 of the 15 bit temperature value when the configuration register Register Address 0x01 7 1 16
30. sis 0 002 Temperature cycle 25 C to 125 C and back to 25 C Repeatability 0 015 C Ta 25 C Drift 0 0073 C 500 hour stress test at 150 C with Voo 5 0 V DC PSRR 0 1 C V Ta 25 C DIGITAL OUTPUTS CT INT OPEN DRAIN High Output Leakage Current lou 0 1 5 uA CT and INT pins pulled up to 5 5 V Output Low Voltage Vo 0 4 V lo 3 mA at 5 5 V lo 1 mAat3 3V Output High Voltage Vou 0 7 x Vop V Output Capacitance Cour 2 pF DIGITAL INPUTS DIN SCLK CS Input Current 1 uA Vin OV to Voo Input Low Voltage Vit 0 4 V Input High Voltage Viu 0 7 x Vop V Pin Capacitance 5 10 pF DIGITAL OUTPUT DOUT Output High Voltage Vou 0 3 V Isource Isink 200 pA Output Low Voltage Vo 0 4 V lo 200 pA Output Capacitance Cour 50 pF POWER REQUIREMENTS Supply Voltage 2 7 5 5 V Supply Current Peak current while converting SPI interface inactive At 3 3 V 210 265 At 5 5 V 250 300 yA 1 SPS Current 1 SPS mode Ta 25 C Rev PrD Page 4 of 26 ADT7320 Parameter Min Typ Max Unit Test Conditions Comments At3 3V 46 Voo 3 3 V At 5 5 V 65 Voo 5 5 V Shutdown Current Supply current in shutdown mode At 3 3 V 2 0 15 uA At5 5V 5 2 25 UA Power Dissipation Normal Mode 700 uw Voo 3 3 V normal mode at 25 C Power Dissipation 1 SPS Mode 150 uW Power dissipated for Vpp 3 3 V Ta 25 C 1 Accuracy specification includes repeatability 2 The equivalent 3 limits are
31. temperature value register and the ID register are read only Table 6 ADT7320 Registers Register Address Description Power On Default 0x00 Status 0x80 0x01 Configuration 0x00 0x02 Temperature value 0x0000 0x03 ID 0xC3 0x04 Tcr setpoint 0x4980 147 C 0x05 Tuyst setpoint 0x05 5 C 0x06 Tun setpoint 0x2000 64 C 0x07 setpoint 0x0500 10 C Table 7 Status Register Register Address 0x00 ADT7320 STATUS REGISTER This 8 bit read only register Register Address 0x00 reflects the status of the overtemperature and undertemperature interrupts that can cause the CT and INT pins to become active It also reflects the status of a temperature conversion operation The interrupt flags in this register are reset by a read operation to the status register and or when the temperature value returns within the temperature limits including hysteresis The RDY bit is reset after a read from the temperature value register In one shot and 1 SPS modes the RDY bit is reset after a write to the operation mode bits in the configuration register Default Bit s Value Type Name Description 3 0 0000 R Unused Reads back 0 4 0 R Tiow This bit is set to 1 when the temperature goes below the Tiow temperature limit The bit is cleared to 0 when the status register is read and or when the temperature measured rises above the limit set in the Tuvsr setpoint reg
32. the peak value of the supply noise is less than 1 mV The RC filter should be mounted as far away as possible from the ADT7320 to ensure that the thermal mass is kept as low as possible TEMPERATURE MEASUREMENT The ADT7320 accurately measures and converts the temperature at the surface of its own semiconductor chip Thermal paths run through the leads the exposed pad as well as the plastic package When the ADT7320 is used to measure the temperature of a nearby heat source the thermal impedance between the heat source and the ADT7320 must be considered because this impedance affects the accuracy and thermal response of the measurement For air or surface temperature measurements take care to isolate the package leads and exposed pad from ambient air temperature Use of a thermally conductive adhesive can help to achieve a more accurate surface temperature measurement QUICK GUIDE TO MEASURING TEMPERATURE The following is a quick guide for measuring temperature in continuous conversion mode default power up mode Execute each step sequentially l After power up reset the serial interface load 32 consecutive 1s on DIN This ensures all internal circuitry is properly initialized 2 Verify the setup by reading the device ID Register Address 0x03 It should read 0xC3 3 After consistent consecutive readings are obtained from Step 2 read the configuration register Register Address 0x01 Register Address 0x04 T
33. tor and a 1 bit digital to analog converter DAC This architecture creates a negative feedback loop and minimizes the integrator output by changing the duty cycle of the comparator output in response to the input voltage changes The comparator samples the output of the integrator at a much higher rate than the input sampling frequency This oversampling spreads the quantization noise over a much wider band than that of the input signal improving overall noise performance and increasing accuracy The modulated output of the comparator is encoded using a circuit technique that results in SPI temperature data Z A MODULATOR INTEGRATOR COMPARATOR VOLTAGE REFERENCE LPF DIGITAL FILTER Figure 11 2 A Modulator TEMPERATURE VALUE REGISTER CLOCK GENERATOR 13 16 BIT 09012 012 ADT7320 The ADT7320 can be configured to operate in any one of the following four operating modes normal mode one shot mode 1 SPS mode and shutdown mode CONTINUOUS CONVERSION MODE In continuous conversion mode default power up mode the ADT7320 runs an automatic conversion sequence During this automatic conversion sequence a conversion takes 240 ms to complete and the ADT7320 is continuously converting This means that as soon as one temperature conversion is completed another temperature conversion begins Each temperature conversion result is stored in the temperature value register and is available through the SPI inter
34. twos complement format Rev PrD Page 17 of 26 ADT7320 Tryst SETPOINT REGISTER The 8 bit Tuysr setpoint register Register Address 0x05 stores the temperature hysteresis value for the Tian Trow and Tour temperature limits The temperature hysteresis value is stored in straight binary format using the four LSBs Increments are possible in steps of 1 C from 0 C to 15 C The value in this register is subtracted from the and Tcrir values and added to the value to implement hysteresis The default setting for the Tuvsr setpoint is 5 C Thich SETPOINT REGISTER The 16 bit setpoint register Register Address 0x06 stores the overtemperature limit value An overtemperature event occurs when the temperature value stored in the temperature value register exceeds the value stored in this register The INT pin is activated if an overtemperature event occurs The temperature is stored in twos complement format with the most significant bit being the temperature sign bit The default setting for the setpoint is 64 Table 12 Tuvsr Setpoint Register Register Address 0x05 Tow SETPOINT REGISTER The 16 bit setpoint register Register Address 0x07 stores the undertemperature limit value An undertemperature event occurs when the temperature value stored in the temperature value register is less than the value stored in this register The INT pin is activated if an undertemperature ev
35. void false triggering due to temperature noise 00 1 fault default 01 2 faults 10 3 faults 11 4 faults 2 0 R W CT pin polarity This bit selects the output polarity of the CT pin 0 active low 1 active high 3 0 R W INTpin polarity This bit selects the output polarity of the INT pin 0 active low 1 active high 4 0 R W INT CT mode This bit selects comparator mode or interrupt mode 0 interrupt mode 1 2 comparator mode 6 5 00 R W Operation mode These two bits set the operational mode of the ADT7320 00 continuous conversion default When one conversion is finished the ADT7320 begins the next conversion 01 one shot mode Conversion time is typically 240 ms 10 1 SPS mode Conversion time is typically 60 ms This operational mode reduces the average current consumption 11 shutdown All circuitry except for the interface circuitry is powered down 7 0 R W Resolution This bit sets the resolution of the ADC when converting 0 13 bit resolution Sign bit 12 bits gives a temperature resolution of 0 0625 C 1 16 bit resolution Sign bit 15 bits gives a temperature resolution of 0 0078 C Rev PrD Page 16 of 26 TEMPERATURE VALUE REGISTER The temperature value register stores the temperature measured by the internal temperature sensor The temperature is stored in a 16 bit twos complement format The temperature is read back from the temperature value register Registe

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