Automotive, 0.5C Accurate, 16-Bit Digital SPI Temperature Sensor ADT7311 Data Sheet FEATURES GENERAL DESCRIPTION Qualified for automotive applications High performance Temperature accuracy 0.5C from -40C to +105C (2.7 V to 3.6 V) 0.4C from -40C to +105C (3.0 V) 16-bit temperature resolution: 0.0078C Fast first 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 W typical at 3.3 V in normal mode 7 W typical at 3.3 V in shutdown mode Wide operating ranges Temperature range: -40C to +150C Voltage range: 2.7 V to 5.5 V Programmable interrupts Critical overtemperature interrupt Overtemperature/undertemperature interrupt SPI-compatible interface 8-lead narrow SOIC RoHS-compliant package The ADT7311 is a high accuracy digital temperature sensor in a narrow 8-lead SOIC package. It contains a band gap temperature reference and a 16-bit ADC to monitor and digitize the temperature to a 0.0078C resolution. The ADC resolution, by default, is set to 13 bits (0.0625C). The ADC resolution is a user programmable mode that can be changed through the serial interface. APPLICATIONS 1. 2. 3. 4. The ADT7311 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 A. The ADT7311 has a shutdown mode that powers down the device and offers a shutdown current of typically 2 A. The ADT7311 is rated for operation over the -40C to +150C temperature range. The CT pin is an open-drain output that becomes active when the temperature exceeds a programmable critical temperature limit. The default critical temperature limit is 147C. The INT pin is also an open-drain output that becomes active when the temperature exceeds a programmable limit. The INT and CT pins can operate in either comparator or interrupt mode. PRODUCT HIGHLIGHTS Battery management Climate control and infotainment Lighting Powertrain Thermocouple cold junction compensation GPS Ease of use, no calibration or correction required by the user. Low power consumption. Excellent long-term stability and reliability. Packaged in an 8-lead SOIC, RoHS-compliant package. FUNCTIONAL BLOCK DIAGRAM ADT7311 SPI INTERFACE DOUT 2 DIN 3 CS 4 INTERNAL REFERENCE INTERNAL OSCILLATOR 6 CT 5 INT 7 GND 8 VDD TCRIT TEMPERATURE VALUE REGISTER CONFIGURATION, STATUS, AND ID REGISTERS THYST REGISTER TCRIT REGISTER THIGH REGISTER TLOW REGISTER TEMPERATURE SENSOR - MODULATOR THIGH FILTER LOGIC TLOW 09050-001 SCLK 1 Figure 1. Rev. 0 Information furnished 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 from its use. Specifications subject to change without notice. No license 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. 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 (c)2011 Analog Devices, Inc. All rights reserved. ADT7311 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Configuration Register .............................................................. 14 Applications....................................................................................... 1 Temperature Value Register ...................................................... 15 General Description ......................................................................... 1 ID Register................................................................................... 15 Product Highlights ........................................................................... 1 TCRIT Setpoint Register ............................................................... 15 Functional Block Diagram .............................................................. 1 THYST Setpoint Register............................................................... 16 Revision History ............................................................................... 2 THIGH Setpoint Register .............................................................. 16 Specifications..................................................................................... 3 TLOW Setpoint Register ............................................................... 16 SPI Timing Specifications ........................................................... 4 Serial Peripheral Interface ............................................................. 17 Absolute Maximum Ratings............................................................ 5 SPI Command Byte.................................................................... 17 ESD Caution.................................................................................. 5 Writing Data ............................................................................... 18 Pin Configuration and Function Descriptions............................. 6 Reading Data............................................................................... 19 Typical Performance Characteristics ............................................. 7 Interfacing to DSPs or Microcontrollers ................................. 19 Theory of Operation ........................................................................ 9 Serial Interface Reset.................................................................. 19 Circuit Information...................................................................... 9 INT and CT Outputs...................................................................... 20 Converter Details.......................................................................... 9 Undertemperature and Overtemperature Detection ............ 20 Temperature Measurement ......................................................... 9 Applications Information .............................................................. 22 One-Shot Mode .......................................................................... 10 Thermal Response Time ........................................................... 22 1 SPS Mode.................................................................................. 10 Supply Decoupling ..................................................................... 22 Shutdown..................................................................................... 11 Powering from a Switching Regulator..................................... 22 Fault Queue ................................................................................. 11 Temperature Monitoring........................................................... 22 Temperature Data Format ......................................................... 12 Quick Guide to Measuring Temperature ................................ 22 Temperature Conversion Formulas ......................................... 12 Outline Dimensions ....................................................................... 23 Registers ........................................................................................... 13 Ordering Guide .......................................................................... 23 Status Register ............................................................................. 13 Automotive Products ................................................................. 23 REVISION HISTORY 9/11--Revision 0: Initial Version Rev. 0 | Page 2 of 24 Data Sheet ADT7311 SPECIFICATIONS TA = -40C to +150C; VDD = 2.7 V to 5.5 V; unless otherwise noted. Table 1. Parameter TEMPERATURE SENSOR AND ADC Accuracy 1 Min ADC Resolution Temperature Resolution 13-Bit 16-Bit Temperature Conversion Time Fast Temperature Conversion Time 1 SPS Conversion Time Temperature Hysteresis Repeatability DC PSRR DIGITAL OUTPUTS (CT, INT), OPEN DRAIN High Output Leakage Current, IOH Output Low Voltage, VOL Output High Voltage, VOH Output Capacitance, COUT DIGITAL INPUTS (DIN, SCLK, CS) Input Current Input Low Voltage, VIL Input High Voltage, VIH Pin Capacitance DIGITAL OUTPUT (DOUT) Output High Voltage, VOH Output Low Voltage, VOL Output Capacitance, COUT POWER REQUIREMENTS Supply Voltage Supply Current At 3.3 V At 5.5 V 1 SPS Current At 3.3 V At 5.5 V Typ Max Unit Test Conditions/Comments -0.05 0.4 0.44 0.5 0.5 0.7 0.8 1.0 13 C C C C C C C Bits 16 Bits TA = -40C to +105C, VDD = 3.0 V TA = -40C to +105C, VDD = 2.7 V to 3.3 V TA = -40C to +125C, VDD = 3.0 V TA = -40C to +105C, VDD = 2.7 V to 3.6 V TA = -40C to +150C, VDD = 2.7 V to 3.6 V TA = -40C to +105C, VDD = 4.5 V to 5.5 V TA = -40C to +150C, VDD = 2.7 V to 5.5 V Twos complement temperature value of sign bit plus 12 ADC bits (power-up default resolution) Twos complement temperature value of sign bit plus 15 ADC bits (Bit 7 = 1 in the configuration register) 0.0625 0.0078 240 6 60 0.002 0.015 0.1 C C ms ms ms C C C/V 13-bit resolution (sign + 12 bits) 16-bit resolution (sign + 15 bits) Continuous conversion and one-shot conversion mode First conversion on power-up only Conversion time for 1 SPS mode Temperature cycle = 25C to 125C and back to 25C TA = 25C TA = 25C A V V CT and INT pins pulled up to 5.5 V IOL = 2 mA at 5.5 V, IOL = 1 mA at 3.3 V 0.1 5 0.4 0.7 x VDD 2 pF 1 0.4 A V V 10 pF 0.7 x VDD 5 V ISOURCE = ISINK = 200 A 0.4 50 V pF IOL = 200 A 5.5 V 265 300 A A Peak current while converting, SPI interface inactive Peak current while converting, SPI interface inactive A A VDD = 3.3 V, 1 SPS mode, TA = 25C VDD = 5.5 V, 1 SPS mode, TA = 25C VOH - 0.3 2.7 210 250 46 65 VIN = 0 V to VDD Rev. 0 | Page 3 of 24 ADT7311 Data Sheet Parameter Shutdown Current At 3.3 V At 5.5 V Power Dissipation Normal Mode Power Dissipation 1 SPS 1 Min Typ Max Unit Test Conditions/Comments 2.0 5.2 700 150 15 25 A A W W Supply current in shutdown mode Supply current in shutdown mode VDD = 3.3 V, normal mode at 25C Power dissipated for VDD = 3.3 V, TA = 25C Accuracy includes lifetime drift. SPI TIMING SPECIFICATIONS TA = -40C to +150C, VDD = 2.7 V to 5.5 V, unless otherwise noted. All input signals are specified with rise time (tR) = fall time (tF) = 5 ns (10% to 90% of VDD) and timed from a voltage level of 1.6 V. Table 2. Parameter1, 2 Limit at TMIN, TMAX Unit Conditions/Comments t1 t2 t3 t4 t5 t6 0 100 100 30 25 5 60 80 10 80 0 0 60 80 10 ns min ns min ns min ns min ns min ns min ns max ns max ns min ns max ns min ns min ns max ns max ns min CS falling edge to SCLK active edge setup time SCLK high pulse width SCLK low pulse width Data setup time prior to SCLK rising edge Data hold time after SCLK rising edge Data access time after SCLK falling edge VDD = 4.5 V to 5.5 V VDD = 2.7 V to 3.6 V Bus relinquish time after CS inactive edge t73 t8 t9 t10 SCLK inactive edge to CS rising edge hold time CS falling edge to DOUT active time VDD = 4.5 V to 5.5 V VDD = 2.7 V to 3.6 V SCLK inactive edge to DOUT low 1 Sample tested during initial release to ensure compliance. All input signals are specified with tR = tF = 5 ns (10% to 90% of VDD) and timed from a voltage level of 1.6 V. See Figure 2. 3 This means that the times quoted in the timing characteristics in Table 2 are the true bus relinquish times of the part and, as such, are independent of external bus loading capacitances. 2 CS t1 t2 1 SCLK t8 t3 2 3 6 7 8 9 10 23 24 t4 t5 LSB t6 t9 DOUT MSB t10 LSB t7 Figure 2. Detailed SPI Timing Diagram Rev. 0 | Page 4 of 24 09050-002 MSB DIN Data Sheet ADT7311 ABSOLUTE MAXIMUM RATINGS Table 3. Parameter VDD to GND DIN Input Voltage to GND DOUT Voltage to GND SCLK Input Voltage to GND CS Input Voltage to GND CT and INT Output Voltage to GND ESD Rating (Human Body Model) Operating Temperature Range1 Storage Temperature Range Maximum Junction Temperature, TJMAX 8-Lead SOIC_N (R-8) Power Dissipation2 Thermal Impedance4 JA, Junction-to-Ambient (Still Air) JC, Junction-to-Case IR Reflow Soldering Peak Temperature (RoHS-Compliant Package) Time at Peak Temperature Ramp-Up Rate Ramp-Down Rate Time from 25C to Peak Temperature Rating -0.3 V to +7 V -0.3 V to VDD + 0.3 V -0.3 V to VDD + 0.3 V -0.3 V to VDD + 0.3 V -0.3 V to VDD + 0.3 V -0.3 V to VDD + 0.3 V 2.0 kV -40C to +150C -65C to +160C 150C 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 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 WMAX = (TJMAX - TA3)/JA 121C/W 56C/W 220C 260C (0C) 20 sec to 40 sec 3C/sec maximum -6C/sec maximum 8 minutes maximum 1 Operating at extended temperatures over prolonged periods depends on the lifetime performance of the part. Consult your local Analog Devices, Inc., account representative for more details. 2 Value relates to package being used on a standard 2-layer PCB. This gives a worst-case JA and JC. 3 TA = 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 is more useful for air-cooled, PCB-mounted components. Rev. 0 | Page 5 of 24 ADT7311 Data Sheet SCLK 1 DOUT 2 DIN 3 ADT7311 TOP VIEW CS 4 (Not to Scale) 8 VDD 7 GND 6 CT 5 INT 09050-005 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Figure 3. Pin Configuration Table 4. Pin Function Descriptions Pin No. 1 2 3 Mnemonic SCLK DOUT DIN 4 5 CS INT 6 CT 7 8 GND VDD Description Serial Clock Input. The serial clock is used to clock in and clock out data to and from any register of the ADT7311. Serial Data Output. Data is clocked out on the SCLK falling edge and is valid on the SCLK rising edge. Serial Data Input. Serial data to be loaded to the part's control registers is provided on this input. Data is clocked into the registers on the rising edge of SCLK. Chip Select Input. The device is selected when this input is low. The device is disabled when this pin is high. Overtemperature and Undertemperature Indicator. Logic output. The power-up default setting is as an active low comparator interrupt. Open-drain configuration. A pull-up resistor is required, typically 10 k. Critical Overtemperature Indicator. Logic output. Power-up default polarity is active low. Open-drain configuration. A pull-up resistor is required, typically 10 k. Analog and Digital Ground. Positive Supply Voltage (2.7 V to 5.5 V). The supply should be decoupled with a 0.1 F ceramic capacitor to GND. Rev. 0 | Page 6 of 24 Data Sheet ADT7311 TYPICAL PERFORMANCE CHARACTERISTICS 300 1.0 5.5V CONTINUOUS CONVERSION 0.6 250 MAX ACCURACY LIMITS 0.4 3.0V CONTINUOUS CONVERSION 200 0.2 IDD (A) 0 150 -0.2 100 -0.4 5.5V 1SPS -0.6 MAX ACCURACY LIMITS 50 -40 -20 0 20 40 60 80 100 120 140 160 TEMPERATURE (C) 0 -100 09050-006 -1.0 -60 0 50 100 150 200 200 TEMPERATURE (C) Figure 4. Temperature Accuracy at 3 V Figure 6. Operating Supply Current vs. Temperature 8 1.0 0.8 7 MAX ACCURACY LIMITS 0.6 6 0.4 5.5V 5 IDD (A) 0.2 0 -0.2 5.0V 4 4.5V 3 -0.4 3.6V 2 -0.6 MAX ACCURACY LIMITS -0.8 -1.0 -60 -40 -20 0 20 40 60 80 3.0V 2.7V 1 100 120 TEMPERATURE (C) 140 160 09050-024 TEMPERATURE ERROR (C) -50 09050-007 3.0V 1SPS -0.8 09050-025 TEMPERATURE ERROR (C) 0.8 0 -100 -50 0 50 100 150 TEMPERATURE (C) Figure 7. Shutdown Current vs. Temperature Figure 5. Temperature Accuracy at 5 V Rev. 0 | Page 7 of 24 ADT7311 Data Sheet 300 160 140 IDD CONTINUOUS CONVERSION 250 TEMPERATURE (C) 120 150 100 60 3.0 3.5 4.0 4.5 5.0 5.5 6.0 SUPPLY VOLTAGE (V) 09050-008 20 0 2.5 Figure 8. Average Operating Supply Current vs. Supply Voltage at 25C 8 7 6 5 4 3 2 1 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) 6.0 09050-009 SHUTDOWN IDD (A) 80 40 IDD 1SPS 50 100 Figure 9. Shutdown Current vs. Supply Voltage at 25C Rev. 0 | Page 8 of 24 0 0 5 10 15 20 25 30 TIME (Seconds) Figure 10. Response to Thermal Shock 35 40 09050-011 IDD (A) 200 Data Sheet ADT7311 THEORY OF OPERATION CIRCUIT INFORMATION - MODULATOR The ADT7311 is a high accuracy digital temperature sensor that uses a 16-bit ADC to monitor and digitize the temperature to 0.0078C of resolution. The ADC resolution, by default, is set to 13 bits (0.0625C). An internal temperature sensor generates a voltage proportional to absolute temperature, which is compared to an internal voltage reference and input into a precision digital modulator. INTEGRATOR COMPARATOR VOLTAGE REF AND VPTAT 1-BIT DAC CLOCK GENERATOR LPF DIGITAL FILTER 13-BIT/ 16-BIT TEMPERATURE VALUE REGISTER 09050-012 1-BIT The internal temperature sensor has high accuracy and linearity over the entire rated temperature range without needing correction or calibration by the user. Figure 11. - Modulator The sensor output is digitized by a sigma-delta (-) modulator, also known as the charge balance type analog-to-digital converter. This type of converter utilizes time-domain oversampling and a high accuracy comparator to deliver 16 bits of resolution in an extremely compact circuit. CONVERTER DETAILS The - modulator consists of an input sampler, a summing network, an integrator, a comparator, and a 1-bit 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 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. TEMPERATURE MEASUREMENT In normal mode (default power-up mode), the ADT7311 runs an automatic conversion sequence. During this automatic conversion sequence, a conversion typically takes 240 ms to complete and the ADT7311 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 interface. 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 147C, the CT pin asserts low. If the temperature exceeds 64C, the INT pin asserts low. Fast conversion temperature accuracy is typically within 5C. 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 TCRIT setpoint read/write register), a high temperature limit (stored in the 16-bit THIGH setpoint read/write register), and a low temperature limit (stored in the 16-bit TLOW setpoint read/write register). If the measured value exceeds these limits, the INT pin is activated; and if it exceeds the TCRIT limit, the CT pin is activated. The INT and CT pins are programmable for polarity via the configuration register, and the INT and CT pins are also programmable for interrupt mode via the configuration register. Rev. 0 | Page 9 of 24 ADT7311 Data Sheet CS 0x08 DIN 0x20 WAIT 240ms MINIMUM FOR CONVERSION TO FINISH DATA 09050-026 DOUT SCLK Figure 12. Typical SPI One-Shot Write to Configuration Register Followed by a Read from the Temperature Value Register ONE-SHOT MODE 1 SPS MODE Setting Bit 6 to 0 and Bit 5 to 1 of the configuration register (Register Address 0x01) enables the one-shot mode. When this mode is enabled, the ADT7311 immediately completes a conversion and then goes into shutdown mode. In this mode, the part performs one measurement per second. A conversion takes only 60 ms, and it remains in the idle state for the remaining 940 ms period. This mode is enabled by writing 1 to Bit 6 and 0 to Bit 5 of the configuration register (Register Address 0x01). Wait for a minimum of 240 ms after writing to the operation mode bits before reading back the temperature from the temperature value register. This time ensures that the ADT7311 has time to power up and complete a conversion. To obtain an updated temperature conversion, reset the Bit 6 to 0 and Bit 5 to 1 in the configuration register (0x01). The one-shot mode is useful when one of the circuit design priorities is to reduce power consumption. Rev. 0 | Page 10 of 24 Data Sheet ADT7311 CT and INT Operation in One-Shot Mode See Figure 13 for more information on one-shot CT pin operation for TCRIT overtemperature events when one of the limits is exceeded. Note that, 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 THIGH - THYST value or goes above the TLOW + THYST 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 TCRIT - THYST 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). When using one-shot mode, ensure that the refresh rate is appropriate to the application being used. SHUTDOWN The ADT7311 can be placed in shutdown mode by writing 1 to Bit 6 and 1 to Bit 5 of the configuration register (Register Address 0x01). The ADT7311 can be taken out of shutdown mode by writing 0 to Bit 6 and 0 to Bit 5 of the configuration register (Register Address 0x01). The ADT7311 typically takes 1 ms (with a 0.1 F decoupling capacitor) to come out of shutdown mode. The conversion result from the last conversion prior to shutdown can still be read from the ADT7311 even when it is in shutdown mode. When the part is taken out of shutdown mode, the internal clock is started 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 ADT7311 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 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 0. TEMPERATURE 149C 148C TCRIT 147C 146C 145C 144C 143C TCRIT - THYST 142C 141C 140C CT PIN POLARITY = ACTIVE LOW CT PIN POLARITY = ACTIVE HIGH TIME WRITE TO BIT 5 AND BIT 6 OF CONFIGURATION REGISTER.* 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. Figure 13. One-Shot CT Pin Rev. 0 | Page 11 of 24 09050-013 WRITE TO BIT 5 AND BIT 6 OF CONFIGURATION REGISTER.* ADT7311 Data Sheet TEMPERATURE DATA FORMAT TEMPERATURE CONVERSION FORMULAS One LSB of the ADC corresponds to 0.0625C in 13-bit mode. The ADC can theoretically measure a temperature range of 255C, but the ADT7311 is guaranteed to measure a low value temperature limit of -40C to a high value temperature limit of +150C. The temperature measurement result is stored in the 16-bit temperature value register and is compared with the high temperature limits stored in the TCRIT setpoint register and the THIGH setpoint register. It is also compared with the low temperature limit stored in the TLOW setpoint register. 16-Bit Temperature Data Format Temperature data in the temperature value register, the TCRIT setpoint register, the THIGH setpoint register, and the TLOW setpoint register is represented by a 13-bit twos complement word. The MSB is the temperature sign bit. The three LSBs, Bit 0 to Bit 2, on power-up, are not part of the temperature conversion result and are flag bits for TCRIT, THIGH, and TLOW. Table 5 shows the 13-bit temperature data format without Bit 0 to Bit 2. 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 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 ADT7311 by ignoring the last four LSBs of the 13-bit temperature value. These four LSBs are Bit 3 to Bit 6 in Table 5. 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) Table 5. 13-Bit Temperature Data Format Temperature -40C -25C -0.0625C 0C +0.0625C +25C +50C +125C +150C Digital Output (Binary) Bits[15:3] 1 1100 1110 0000 1 1110 0111 0000 1 1111 1111 1111 0 0000 0000 0000 0 0000 0000 0001 0 0001 1001 0000 0 0011 0010 0000 0 0111 1101 0000 0 1001 0110 0000 Negative Temperature = ADC Code(dec) - 512 Digital Output (Hex) 0x1CE0 0x1E70 0x1FFF 0x000 0x001 0x190 0x320 0x7D0 0x960 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. 0 | Page 12 of 24 Data Sheet ADT7311 REGISTERS STATUS REGISTER The ADT7311 contains eight registers: * * * * 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 go 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. A status register A configuration register Five temperature registers An ID register The status register, temperature value register, and the ID register are read-only. Table 6. ADT7311 Registers Register Address 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 Power-On Default 0x80 0x00 0x0000 0xC3 0x4980 (147C) 0x05 (5C) 0x2000 (64C) 0x0500 (10C) Description Status Configuration Temperature value ID TCRIT setpoint THYST setpoint THIGH setpoint TLOW setpoint Table 7. Status Register (Register Address 0x00) Bit [3:0] 4 Default Value 0000 0 Type R R Name Unused TLOW 5 0 R THIGH 6 0 R TCRIT 7 1 R RDY Description Reads back 0. This bit is set to 1 when the temperature goes below the TLOW temperature limit. The bit clears to 0 when the status register is read and/or when the temperature measured goes back above the limit set in the TLOW + THYST setpoint registers. This bit is set to 1 when the temperature rises above the THIGH temperature limit. The bit clears to 0 when the status register is read and/or when the temperature measured drops below the limit set in the THIGH - THYST setpoint registers. This bit is set to 1 when the temperature rises above the TCRIT temperature limit. This bit clears to 0 when the status register is read and/or when the temperature measured drops below the limit set in the TCRIT - THYST setpoint registers. This bit goes low when the temperature conversion result is written into 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. Rev. 0 | Page 13 of 24 ADT7311 Data Sheet CONFIGURATION REGISTER This 8-bit read/write register (Register Address 0x01) stores various configuration modes for the ADT7311, including shutdown, overtemperature and undertemperature interrupts, one-shot, continuous conversion, interrupt pins polarity, and overtemperature fault queues. Table 8. Configuration Register (Register Address 0x01) Bit [1:0] Default Value 00 Type R/W Name Fault queue 2 0 R/W CT pin polarity 3 0 R/W INT pin polarity 4 0 R/W INT/CT mode [6:5] 00 R/W Operation mode 7 0 R/W Resolution Description These two bits set the number of undertemperature/overtemperature faults that can occur before setting the INT and CT pins. This helps to avoid false triggering due to temperature noise. 00 = 1 fault (default). 01 = 2 faults. 10 = 3 faults. 11 = 4 faults. This bit selects the output polarity of the CT pin. 0 = active low. 1 = active high. This bit selects the output polarity of the INT pin. 0 = active low. 1 = active high. This bit selects between comparator mode and interrupt mode. 0 = interrupt mode. 1 = comparator mode. These two bits set the operational mode for the ADT7311. 00 = continuous conversion (default). When one conversion is finished, the ADT7311 starts another. 01 = one shot. 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 interface circuitry is powered down. This bit sets up the resolution of the ADC when converting. 0 = 13-bit resolution. Sign bit + 12 bits gives a temperature resolution of 0.0625C. 1 = 16-bit resolution. Sign bit + 15 bits gives a temperature resolution of 0.0078C. Rev. 0 | Page 14 of 24 Data Sheet ADT7311 TEMPERATURE VALUE REGISTER ID REGISTER The temperature value register stores the temperature measured by the internal temperature sensor. The temperature is stored as a 16-bit twos complement format. The temperature is read back from the temperature value register (Register Address 0x02) as a 16-bit value. 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. Bit 2, Bit 1, and Bit 0 are event alarm flags for TCRIT, THIGH, and TLOW. 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 the extended digital value. TCRIT SETPOINT REGISTER The 16-bit TCRIT 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 temperature is stored in twos complement format with the MSB being the temperature sign bit. The default setting for the TCRIT setpoint is 147C. Table 9. Temperature Value Register (Register Address 0x02) Bit 0 Default Value 0 Type R Name TLOW flag/LSB0 1 0 R THIGH flag/LSB1 2 0 R TCRIT flag/LSB2 [7:3] [14:8] 15 00000 0000000 0 R R R Temp Temp Sign Description Flags a TLOW event if the configuration register, Register Address 0x01[7] = 0 (13-bit resolution). When the temperature value is below TLOW, this bit it set to 1. Contains the Least Significant Bit 0 of the 15-bit temperature value if the configuration register, Register Address 0x01[7] = 1 (16-bit resolution). Flags a THIGH event if the configuration register, Register Address 0x01[7] = 0 (13-bit resolution). When the temperature value is above THIGH, this bit it set to 1. Contains the Least Significant Bit 1 of the 15-bit temperature value if the configuration register, Register Address 0x01[7] = 1 (16-bit resolution). Flags a TCRIT event if the configuration register, Register Address 0x01[7] = 0 (13-bit resolution). When the temperature value exceeds TCRIT, this bit it 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). Temperature value in twos complement format. Temperature value in twos complement format. Sign bit, indicates if the temperature value is negative or positive. Table 10. ID Register (Register Address 0x03) Bit [2:0] [7:3] Default Value 011 11000 Type R R Name Revision ID Manufacturer ID Description Contains the silicon revision identification number. Contains the manufacturer identification number. Table 11. TCRIT Setpoint Register (Register Address 0x04) Bit Default Value Type Name Description [15:0] 0x4980 R/W TCRIT 16-bit critical overtemperature limit, stored in twos complement format. Rev. 0 | Page 15 of 24 ADT7311 Data Sheet THYST SETPOINT REGISTER The THYST setpoint 8-bit register (Register Address 0x05) stores the temperature hysteresis value for the THIGH, TLOW, and TCRIT temperature limits. The temperature hysteresis value is stored in straight binary format using four LSBs. Increments are possible in steps of 1C from 0C to 15C. The value in this register is subtracted from the THIGH and TCRIT values and added to the TLOW value to implement hysteresis. The default setting for the THYST setpoint is 5C. THIGH SETPOINT REGISTER The 16-bit THIGH 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 THIGH setpoint is 64C. TLOW SETPOINT REGISTER The 16-bit TLOW 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 event occurs. The temperature is stored in twos complement format with the MSB being the temperature sign bit. The default setting for the TLOW setpoint is 10C. Table 12. THYST Setpoint Register (Register Address 0x05) Bit Default Value Type Name Description [3:0] 0101 R/W THYST Hysteresis value, from 0C to 15C. Stored in straight binary format. The default setting is 5C. [7:4] 0000 R/W N/A Not used. Table 13. THIGH Setpoint Register (Register Address 0x06) Bit Default Value Type Name Description [15:0] 0x2000 R/W THIGH 16-bit overtemperature limit, stored in twos complement format. Table 14. TLOW Setpoint Register (Register Address 0x07) Bit Default Value [15:0] 0x0500 Type Name Description R/W TLOW 16-bit undertemperature limit, stored in twos complement format. Rev. 0 | Page 16 of 24 Data Sheet ADT7311 SERIAL PERIPHERAL INTERFACE PULL-UP VDD VDD VDD ADT7311 SCLK DOUT DIN CS 10k GND CT INT 09050-014 MICROCONTROLLER 10k 0.1F Figure 14. Typical SPI Interface Connection The ADT7311 has a 4-wire serial peripheral interface (SPI). The interface has a data input pin (DIN) for inputting data to the device, a data output pin (DOUT) for reading data back from the device, and a 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 of the ADT7311 on the negative edge of SCLK, and data is clocked into the device on the positive edge of SCLK. Bit C7, Bit C2, Bit C1, and Bit C0 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. 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. This indicates to the ADT7311 whether the transaction is a read or a write and provides the address of the register for the data transfer. Table 15 shows the format of the command byte. Table 15. Command Byte C7 0 C6 R/W C5 C4 C3 Register address C2 0 C1 0 C0 0 Rev. 0 | Page 17 of 24 ADT7311 Data Sheet Figure 15 shows a write to an 8-bit register, and Figure 16 shows a write to a 16-bit register. WRITING DATA Data is written to the ADT7311 in eight bits or 16 bits, depending on the addressed register. The first byte written to the device is the command byte, with the read/write bit set to 0. The master then supplies the 8-bit or 16-bit input data on the DIN line. The ADT7311 clocks the data into the register addressed in the command byte on the positive edge of SCLK. The master finishes the write by pulling CS high. The master must begin a new write transaction on the bus for every register write. Only one register is written to per bus transaction. CS 1 2 3 4 5 6 7 8 9 10 11 DIN 0 R/W C6 REGISTER ADDR 0 0 0 C4 C2 C1 C0 C5 C3 13 14 15 16 8-BIT DATA 8-BIT COMMAND BYTE C7 12 D7 D6 D5 D4 D3 D2 D1 09050-028 SCLK D0 Figure 15. Writing to an 8-Bit Register CS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 DIN R/W C7 C6 REGISTER ADDR 0 0 0 C5 C2 C1 C0 C4 C3 16 17 22 23 24 16-BIT DATA 8-BIT COMMAND BYTE 0 15 D15 D14 D13 D12 D11 D10 Figure 16. Writing to a 16-Bit Register Rev. 0 | Page 18 of 24 D9 D8 D7 D2 D1 D0 09050-029 SCLK Data Sheet ADT7311 CS can be tied to ground, and the serial interface can be operated in a 3-wire mode. DIN, DOUT, and SCLK are used to communicate with the ADT7311 in this mode. READING DATA A read transaction begins when the master writes the command byte to the ADT7311 with the read/write bit set to 1. The master then supplies eight or 16 clock pulses, depending on the addressed register, and the ADT7311 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. 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 ADT7311 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 gets lost due to a software error or some glitch in the system. Reset returns the interface to the state in which it is expecting a write to the communications register. This operation resets the contents of all registers to their power-on values. Following a reset, the user should allow a period of 500 s before addressing the serial interface. The read transaction finishes when the master takes CS high. INTERFACING TO DSPs OR MICROCONTROLLERS The ADT7311 can be operated with CS used as a frame synchronization signal. This scheme 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 specifications in Table 2 are obeyed. CS SCLK 2 1 4 3 5 7 6 9 8 11 10 12 13 14 16 15 8-BIT COMMAND WORD DIN 0 R/W C7 C6 REGISTER ADDR C5 C4 C3 0 0 0 C2 C1 C0 DOUT D7 D6 D5 D4 D3 15 16 D2 D1 09050-030 8-BIT DATA D0 Figure 17. Reading from an 8-Bit Register CS SCLK 1 2 3 4 5 6 7 8 9 10 11 12 13 14 17 22 23 24 8-BIT COMMAND BYTE DIN 0 R/W C7 C6 REGISTER ADDR 0 0 0 C4 C2 C1 C0 C5 C3 DOUT D15 D14 D13 D12 D11 D10 Figure 18. Reading from a 16-Bit Register Rev. 0 | Page 19 of 24 D9 D8 D7 D2 D1 D0 09050-031 16-BIT DATA ADT7311 Data Sheet INT AND CT OUTPUTS Comparator Mode The INT and CT pins are open-drain outputs, and both pins require a 10 k pull-up resistor to VDD. The ADT7311 must be fully powered up to VDD before reading INT and CT data. In comparator mode, the INT pin returns to its inactive status when the temperature drops below the THIGH - THYST limit or rises above the TLOW + THYST limit. UNDERTEMPERATURE AND OVERTEMPERATURE DETECTION Putting the ADT7311 into shutdown mode does not reset the INT state in comparator mode. 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 in the THIGH setpoint register or less than the temperature stored in the TLOW setpoint register. How this pin reacts after this event depends on the overtemperature mode selected. Interrupt Mode In interrupt mode, the INT pin goes inactive when any ADT7311 register is read. When the INT pin is reset, it goes active again only when the temperature is greater than the temperature stored in the THIGH setpoint register or less than the temperature stored in the TLOW setpoint register. Placing the ADT7311 into shutdown mode resets the INT pin in the interrupt mode. Figure 19 illustrates the comparator and interrupt modes for events exceeding the THIGH limit with both pin polarity settings. Figure 20 illustrates the comparator and interrupt modes for events exceeding the TLOW limit with both pin polarity settings. TEMPERATURE 82C 81C THIGH 80C 79C 78C 77C 76C THIGH - THYST 75C 74C 73C INT PIN (COMPARATOR MODE) POLARITY = ACTIVE LOW INT PIN (INTERRUPT MODE) POLARITY = ACTIVE LOW INT PIN (COMPARATOR MODE) POLARITY = ACTIVE HIGH TIME READ READ READ 09050-020 INT PIN (INTERRUPT MODE) POLARITY = ACTIVE HIGH Figure 19. INT Output Temperature Response Diagram for THIGH Overtemperature Events Rev. 0 | Page 20 of 24 Data Sheet ADT7311 TEMPERATURE -13C -14C TLOW + THYST -15C -16C -17C -18C -19C TLOW -20C -21C -22C INT PIN (COMPARATOR MODE) POLARITY = ACTIVE LOW INT PIN (INTERRUPT MODE) POLARITY = ACTIVE LOW INT PIN (COMPARATOR MODE) POLARITY = ACTIVE HIGH TIME READ READ READ 09050-021 INT PIN (INTERRUPT MODE) POLARITY = ACTIVE HIGH Figure 20. INT Output Temperature Response Diagram for TLOW Undertemperature Events Rev. 0 | Page 21 of 24 ADT7311 Data Sheet 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 the IC is mounted to. For example, a large PCB containing large amounts of copper tracking can act as a large heat sink and slow the thermal response. For a faster thermal response, it is recommended to mount the sensor on as small a PCB as possible. ADT7311 operates within specification. The RC filter should be mounted as far away as possible from the ADT7311 to ensure that the thermal mass is kept as low as possible. For additional information, contact Analog Devices. TEMPERATURE MONITORING SUPPLY DECOUPLING The ADT7311 is ideal for monitoring the thermal environment within hazardous automotive applications. The die accurately reflects the thermal conditions that affect nearby integrated circuits. The ADT7311 must have a decoupling capacitor connected between VDD and GND; otherwise, incorrect temperature readings will be obtained. A 0.1 F decoupling capacitor, such as a high frequency ceramic type, must be used and mounted as close as possible to the VDD pin of the ADT7311. The ADT7311 measures and converts the temperature at the surface of its own semiconductor chip. When the ADT7311 is used to measure the temperature of a nearby heat source, the thermal impedance between the heat source and the ADT7311 must be considered. If possible, the ADT7311 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 F ceramic capacitor is critical for the temperature accuracy specifications to be achieved. When the thermal impedance is determined, the temperature of the heat source can be inferred from the ADT7311 output. As much as 60% of the heat transferred from the heat source to the thermal sensor on the ADT7311 die is discharged via the copper tracks and the bond pads. Of the pads on the ADT7311, the GND pad transfers most of the heat. Therefore, to measure the temperature of a heat source, it is recommended that the thermal resistance between the ADT7311 GND pad and the GND of the heat source be reduced as much as possible. TTL/CMOS LOGIC CIRCUITS 0.1F QUICK GUIDE TO MEASURING TEMPERATURE ADT7311 POWER SUPPLY 09050-022 1. 2. 3. Figure 21. Use of Separate Traces to Reduce Power Supply Noise POWERING FROM A SWITCHING REGULATOR Precision analog devices such as the ADT7311 require a wellfiltered power source. If the ADT7311 is powered from a switching regulator, noise may be generated in the 50 kHz to 3 MHz range that may affect the temperature accuracy specification. To prevent this, it is recommended to connect an RC filter between the power supply and VDD. The value of components used should be carefully considered to ensure that the 4. Rev. 0 | Page 22 of 24 After power-up, reset the serial interface (load 32 consecutive 1s on DIN). This ensures all internal circuitary is properly initialized. Verify the setup by reading the device ID (Register Address 0x03). It should read 0xC3. After consistent consecutive readings are obtained from Step 2, proceed to read the configuration register (0x01), TCRIT (0x04), THIGH (0x06), and TLOW (0x07). Compare to the specified defaults in Table 6. If all the readings match, the interface is operational. Write to the configuration register to set theADT7311 to the desired configuration. Read the temperature value register. It should produce a valid temperature measurement. Data Sheet ADT7311 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 8 1 5 4 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) COPLANARITY 0.10 SEATING PLANE 6.20 (0.2441) 5.80 (0.2284) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) 0.31 (0.0122) 0.50 (0.0196) 0.25 (0.0099) 45 8 0 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) COMPLIANT TO JEDEC STANDARDS MS-012-AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. 012407-A 4.00 (0.1574) 3.80 (0.1497) Figure 22. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) ORDERING GUIDE Model 1, 2 ADT7311WTRZ ADT7311WTRZ-RL ADT7311WTRZ-RL7 EVAL-ADT7X10EBZ Temperature Range 3 -40C to +150C -40C to +150C -40C to +150C Temperature Accuracy 4 0.5C 0.5C 0.5C Package Description 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N Evaluation Board Package Option R-8 R-8 R-8 1 Z = RoHS Compliant Part. W = Qualified for Automotive Applications. 3 Operating at extended temperatures over prolonged periods depends on the lifetime performance of the part. 4 Maximum accuracy over the -40C to +105C temperature range (VDD = 2.7 V to 3.6 V) 2 AUTOMOTIVE PRODUCTS The ADT7311W models are available with controlled manufacturing to support the quality and reliability requirements of automotive applications. Note that these automotive models may have specifications that differ from the commercial models; therefore, designers should review the Specifications section of this data sheet carefully. Only the automotive grade products shown are available for use in automotive applications. Contact your local Analog Devices account representative for specific product ordering information and to obtain the specific Automotive Reliability reports for these models. Rev. 0 | Page 23 of 24 ADT7311 Data Sheet NOTES (c)2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D09050-0-9/11(0) Rev. 0 | Page 24 of 24