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0.5C Accurate, 16-Bit Digital SPI Temperature Sensor ADT7310
FEATURES
13- or 16-bit user selectable temperature-to-digital converter Temperature accuracy 0.5C from -40C to +105C No temperature calibration/correction required by user Power saving 1 sample per second (SPS) mode Fast first conversion on power-up of 6 ms SPI-compatible interface Operating temperature from -55C to +150C Operating voltage: 2.7 V to 5.5 V Critical overtemperature indicator Programmable overtemperature/undertemperature interrupt Low power consumption: 700 W typical at 3.3 V Shutdown mode for lower power: 7W typical at 3.3 V 8-lead narrow SOIC RoHS-compliant package
GENERAL DESCRIPTION
The ADT7310 is a high accuracy digital temperature sensor in a narrow SOIC package. It contains a band gap temperature reference and a 13-bit ADC to monitor and digitize the temperature to a 0.0625C resolution. The ADC resolution, by default, is set to 13 bits (0.0625 C). This can be changed to 16 bits (0.0078 C) by setting Bit 7 in the configuration register (Register Address 0x01). The ADT7310 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 ADT7310 has a shutdown mode that powers down the device and offers a shutdown current of typically 2 A. The ADT7310 is rated for operation over the -55C 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.
APPLICATIONS
Medical equipment Environmental control systems Computer thermal monitoring Thermal protection Industrial process control Power system monitors Hand-held applications
FUNCTIONAL BLOCK DIAGRAM
SPI INTERFACE SCLK 1 DOUT 2 DIN 3 CS 4
ADT7310
INTERNAL REFERENCE INTERNAL OSCILLATOR
6
CT
TCRIT TEMPERATURE SENSOR - MODULATOR
5
TEMPERATURE VALUE REGISTER THYST REGISTER THIGH REGISTER
CONFIGURATION AND STATUS REGISTERS TCRIT REGISTER TLOW REGISTER
INT
THIGH FILTER LOGIC TLOW
7 8
GND VDD
07789-001
Figure 1.
Rev. 0
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ADT7310 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications ....................................................................................... 1 General Description ......................................................................... 1 Functional Block Diagram .............................................................. 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 SPI Timing Specifications ........................................................... 4 Absolute Maximum Ratings............................................................ 5 ESD Caution .................................................................................. 5 Pin Configuration and Function Descriptions ............................. 6 Typical Performance Characteristics ............................................. 7 Theory of Operation ........................................................................ 9 Circuit Information ...................................................................... 9 Converter Details.......................................................................... 9 Temperature Measurement ......................................................... 9 One-Shot Mode .......................................................................... 10 1 SPS Mode .................................................................................. 10 Continuous Read Mode ............................................................. 12 Shutdown ..................................................................................... 12 Fault Queue ................................................................................. 12 Temperature Data Format ......................................................... 13 Temperature Conversion Formulas ......................................... 13 Registers ........................................................................................... 14 Status Register ............................................................................. 14 Configuration Register .............................................................. 15 Temperature Value Register ...................................................... 16 ID Register................................................................................... 16 TCRIT Setpoint Register ............................................................... 16 THYST Setpoint Register............................................................... 17 THIGH Setpoint Register .............................................................. 17 TLOW Setpoint Register ............................................................... 17 Serial Interface ................................................................................ 18 SPI Command Byte .................................................................... 18 Writing Data ............................................................................... 19 Reading Data............................................................................... 20 Interfacing to DSPs or Microcontrollers ................................. 20 Serial Interface Reset.................................................................. 20 INT and CT Outputs...................................................................... 21 Undertemperature and Overtemperature Detection ............ 21 Applications Information .............................................................. 23 Thermal Response Time ........................................................... 23 Supply Decoupling ..................................................................... 23 Temperature Monitoring ........................................................... 23 Outline Dimensions ....................................................................... 24 Ordering Guide .......................................................................... 24
REVISION HISTORY
4/09--Revision 0: Initial Version
Rev. 0 | Page 2 of 24
ADT7310 SPECIFICATIONS
TA = -55C to +150C; VDD = 2.7 V to 5.5 V; unless otherwise noted. Table 1.
Parameter TEMPERATURE SENSOR AND ADC Accuracy 1 Min Typ Max 0.5 0.7 0.8 1.0 13 16 Temperature Resolution 13 Bit 16 Bit Temperature Conversion Time Fast Temperature Conversion Time 1 SPS Conversion Time Temperature Hysteresis Repeatability DC PSRR DIGITAL OUTPUTS (OPEN DRAIN) High Output Leakage Current, IOH Output High Current Output Low Voltage, VOL Output High Voltage, VOH Output Capacitance, COUT DIGITAL INPUTS 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 3.3V At 5.5V Shutdown Current At 3.3 V At 5.5 V Power Dissipation Normal Mode Power Dissipation 1 SPS
1
Unit C C C C Bits Bits
Test Conditions/Comments TA = -40C to +105C, VDD = 2.7 V to 3.6 V TA = -55C to +150C, VDD = 2.7 V to 3.6 V TA = -40C to +105C, VDD = 4.5 V to 5.5 V TA = -55C 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) 13-bit resolution (sign + 12-bit) 16-bit resolution (sign + 15-bit) 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 CT and INT pins pulled up to 5.5 V VOH = 5 .5V IOL = 2 mA @ 5.5 V, IOL = 1 mA @ 3.3 V
ADC Resolution
0.0625 0.0078 240 6 60 0.02 0.01 0.1 0.1 5 1 0.4
C C ms ms ms C C C/V A mA V V pF A V V pF V V pF V A A A A 15 25 A A W W
0.7 x VDD 3 1 0.4 0.7 x VDD 5 VOH - 0.3 0.4 50 2.7 210 230 46 65 2.0 4.4 700 150 5.5 250 300 10
VIN = 0 V to VDD
ISOURCE = ISINK = 200 A IOL = 200 A
Peak current while converting, SPI interface inactive Peak current while converting, SPI interface inactive VDD = 3.3 V, 1 SPS mode, TA = 25C VDD = 5.5 V, 1 SPS mode, TA = 25C 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.
Rev. 0 | Page 3 of 24
ADT7310
SPI TIMING SPECIFICATIONS
TA = -55C 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.
Parameter 1, 2 t1 t2 t3 t4 t5 t6 Limit at TMIN, TMAX (B Version) 0 100 100 30 25 0 60 80 10 80 0 0 60 80 10 Unit 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 Conditions/Comments CS falling edge to SCLK active edge setup time3 SCLK high pulse width SCLK low pulse width Data valid to SCLK edge setup time Data valid to SCLK edge hold time SCLK active edge to data valid delay 3 VDD = 4.5 V to 5.5 V VDD = 2.7 V to 3.6 V Bus relinquish time after CS inactive edge CS rising edge to SCLK 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 high
t7 4 t8 t9
t10
1 2 3
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. SCLK active edge is falling edge of SCLK. 4 This means that the times quoted in the timing characteristics are the true bus relinquish times of the part and, as such, are independent of external bus loading capacitances.
CS
t1
t2
1 2
t3
3 7 8 1 2 7
t8
8
SCLK
t4
DIN
t5
MSB LSB
DOUT
MSB
LSB
Figure 2. Detailed SPI Timing Diagram
ISINK (1.6mA WITH VDD = 5V, 100A WITH VDD = 3V) TO OUTPUT PIN
1.6V
10pF
ISOURCE (200A WITH VDD = 5V, 100A WITH VDD = 3V)
07789-004
Figure 3. Load Circuit for Timing Characterization
Rev. 0 | Page 4 of 24
07789-002
t9
t6
t10 t7
ADT7310 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 Range Storage Temperature Range Maximum Junction Temperature, TJMAX 8-Lead SOIC-N (R-8) Power Dissipation1 Thermal Impedance3 JA, Junction-to-Ambient (Still Air) JC, Junction-to-Case IR Reflow Soldering Peak Temperature (RoHSCompliant Package) Time at Peak Temperature Ramp-Up Rate Ramp-Down Rate Time from 25C to Peak Temperature
1
MAXIMUM POWER DISSIPATION (W)
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 -55C to +150C -65C to +160C 150C WMAX = (TJMAX - TA2)/JA 121C/W 56C/W 220C 260C (0C) 20 sec to 40 sec 3C/sec maximum -6C/sec maximum 8 minutes maximum
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.
1.2
1.0
0.8
0.6
0.4
0.2
MAX PD = 3.4mW AT 150C
TEMPERATURE (C)
Figure 4. SOIC_N Maximum Power Dissipation vs. Temperature
ESD CAUTION
Values relate to package being used on a standard 2-layer PCB. This gives a worst-case JA and JC. See Figure 4 for a plot of maximum power dissipation vs. ambient temperature (TA). 2 TA = ambient temperature. 3 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
07789-003
0
-55 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
ADT7310 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
SCLK 1 DOUT 2 DIN 3
8
ADT7310
VDD GND INT
07789-005
7 6 5
TOP VIEW CS 4 (Not to Scale)
CT
Figure 5. Pin Configuration
Table 4. Pin Function Descriptions
Pin No. 1 2 3 4 5 6 7 8 Mnemonic SCLK DOUT DIN CS INT CT 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 ADT7310. 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. 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 ground.
Rev. 0 | Page 6 of 24
ADT7310 TYPICAL PERFORMANCE CHARACTERISTICS
1.0 0.8
TEMPERATURE ERROR (C) 0.30
5.5V CONTINUOUS CONVERSION 3.0V CONTINUOUS CONVERSION
0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -40 -20
MAX ACCURACY LIMITS
0.25
0.20
IDD (mA)
0.15
0.10
MAX ACCURACY LIMITS
0.05
5.5V 1SPS
3.0V 1SPS
-50
0
50
100
150
200
TEMPERATURE (C)
TEMPERATURE (C)
Figure 6. Temperature Accuracy at 3 V
1.0 0.8
MAX ACCURACY LIMITS
Figure 8. Operating Supply Current vs. Temperature
6
TEMPERATURE ERROR (C)
0.6
5 SHUTDOWN IDD (A)
0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 -60
-40 -20 0 MAX ACCURACY LIMITS
4
5.5V 5.0V
3
4.5V
2
3.6V 3.0V 2.7V
-50 0 50 100 150 200
07789-025
1
TEMPERATURE (C)
07789-024
20
40
60
80
100
120
140
160
0 -100
TEMPERATURE (C)
Figure 7. Temperature Accuracy at 5 V
Figure 9. Shutdown Current vs. Temperature
Rev. 0 | Page 7 of 24
07789-007
0
20
40
60
80
100
120
140
160
07789-006
-1.0 -60
0 -100
ADT7310
0.30 IDD CONTINUOUS CONVERSION
160 140 120
0.25
0.20
TEMPERATURE (C)
IDD 1SPS 3.0 3.5 4.0 4.5 5.0 5.5 6.0
07789-008
100 80 60 40 20 0
IDD (mA)
0.15
0.10
0.05
0
5
10
15
20
25
30
35
40
SUPPLY VOLTAGE (V)
TIME (Seconds)
Figure 10. Average Operating Supply Current vs. Supply Voltage at 25C
Figure 12. Response to Thermal Shock
8 7 6
SHUTDOWN IDD (A)
5 4 3 2 1 0 2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
SUPPLY VOLTAGE (V)
Figure 11. Shutdown Current vs. Supply Voltage at 25C
07789-009
Rev. 0 | Page 8 of 24
07789-011
0 2.5
ADT7310 THEORY OF OPERATION
CIRCUIT INFORMATION
The ADT7310 is a 13-bit digital temperature sensor that is extendable to 16-bits for greater resolution. An on-board temperature sensor generates a voltage proportional to absolute temperature, which is compared to an internal voltage reference and input to a precision digital modulator. The on-board temperature sensor has excellent accuracy and linearity over the entire rated temperature range without needing correction or calibration by the user. The sensor output is digitized by a sigma-delta (-) modulator, also known as the charge balance type analog-todigital 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. Configuration register functions consist of * * * * * * Switching between 13-bit and 16-bit resolution Switching between normal operation and full power-down Switching between comparator and interrupt event modes on the INT and CT pins Setting the active polarity of the CT and INT pins Setting the number of faults that activate CT and INT Enabling the standard one-shot mode and 1 SPS mode
VOLTAGE REF AND VPTAT - MODULATOR INTEGRATOR COMPARATOR
1-BIT DAC
1-BIT
07789-012
CLOCK GENERATOR
LPF DIGITAL FILTER
13-BIT
TEMPERATURE VALUE REGISTER
Figure 13. - Modulator
TEMPERATURE MEASUREMENT
In normal mode, the ADT7310 runs an automatic conversion sequence. During this automatic conversion sequence, a conversion takes 240 ms to complete and the ADT7310 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.
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.
Rev. 0 | Page 9 of 24
ADT7310
CS
DIN
0x08
0x20 WAIT 240ms MINIMUM FOR CONVERSION TO FINISH
DOUT
DATA
SCLK
Figure 14. Typical SPI One-Shot Write to Configuration Register Followed by a Read from the Temperature Value Register
ONE-SHOT MODE
Setting Bit 5 to 1 and Bit 6 to 0 of the configuration register (Register Address 0x01) enables the one-shot mode. When this mode is enabled, the ADT7310 immediately completes a conversion and then goes into shutdown mode. Wait for a minimum of 240 ms after writing to the one-shot bits before reading back the temperature from the temperature value register. This time ensures that the ADT7310 has time to power up and complete a conversion. The one-shot mode is useful when one of the circuit design priorities is to reduce power consumption.
1 SPS 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 0 to Bit 5 and 1 to Bit 6 of the configuration register (Register Address 0x01).
Rev. 0 | Page 10 of 24
07789-026
ADT7310
CT and INT Operation in One-Shot Mode
See Figure 15 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 the comparator mode, if the temperature drops below the THIGH - THYST value or goes above the TLOW + THYST value, a write to the one-shot bits (Bit 5 and Bit 6 of the configuration register, Register Address 0x01) resets the INT pin.
TEMPERATURE 149C 148C 147C 146C 145C 144C 143C 142C 141C 140C TCRIT - THYST TCRIT
For the CT pin in the comparator mode, if the temperature drops below the TCRIT - THYST value, a write to the one-shot bits (Bit 5 and Bit 6 of the configuration register, Register Address 0x01) resets the CT pin; see Figure 15. Note that when using one-shot mode, ensure that the refresh rate is appropriate to the application being used.
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.* WRITE TO BIT 5 AND BIT 6 OF CONFIGURATION REGISTER.*
07789-013
*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 15. One-Shot CT Pin
Rev. 0 | Page 11 of 24
ADT7310
CONTINUOUS READ MODE
When the command byte = 01010100 (0x54), the contents of the temperature value register can be read out without requiring repeated writes to the communications register. By sending 16 SCLK clocks to the ADT7310, the contents of the temperature value register are output onto the DOUT pin. To exit the continuous read mode, the Command Byte 01010000 (0x50) must be written to the ADT7310. While in continuous read mode, the part monitors activity on the DIN line so that it can receive the instruction to exit the continuous read mode. Additionally, a reset occurs if 32 consecutive 1s are seen on the DIN pin. Therefore, hold DIN low in continuous read mode until an instruction is to be written to the device. In continuous read mode, the temperature value register cannot be read when a conversion is taking place. If an attempt is made to read the temperature value register while a conversion is taking place, then all 0s are read. This is because the continuous read mode blocks read access to temperature value register during a conversion.
SHUTDOWN
The ADT7310 can be placed in shutdown mode by writing 1 to Bit 5 and 1 to Bit 6 of the configuration register (Register Address 0x01). The ADT7310 can be taken out of shutdown mode by writing 0 to Bit 5 and 0 to Bit 6 of the configuration register (Register Address 0x01). The ADT7310 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 ADT7310 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 ADT7310 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 zero.
CS
DIN
0x54
DOUT
TEMPERATURE VALUE
TEMPERATURE VALUE
TEMPERATURE VALUE
Figure 16. Continuous Read Mode
Rev. 0 | Page 12 of 24
07789-027
SCLK
ADT7310
TEMPERATURE DATA FORMAT
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 ADT7310 is guaranteed to measure a low value temperature limit of -55C 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. Temperature data in the temperature value register, the TCRIT setpoint register, the THIGH setpoint register, and the TLOW setpoint register are 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. 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 ADT7310 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 -55C -50C -25C -0.0625C 0C +0.0625C +25C +50C +125C +150C Digital Output (Binary) Bits[15:3] 1 1100 1001 0000 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 Digital Output (Hex) 0x1C90 0x1CE0 0x1E70 0x1FFF 0x000 0x001 0x190 0x320 0x7D0 0x960
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. 0 | Page 13 of 24
ADT7310 REGISTERS
The ADT7310 contains eight registers: * * * * A status register A configuration register Five temperature registers An ID register
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 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 hysterisis. 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 one-shot bits.
The status register, temperature value register, and the ID register are read-only. Table 6. ADT7310 Registers
Register Address 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 Description Status Configuration Temperature value ID TCRIT setpoint THYST setpoint THIGH setpoint TLOW setpoint Power-On Default 0x80 0x00 0x0000 0xCX 0x4980 (147C) 0x05 (5C) 0x2000 (64C) 0x0500 (10C)
Table 7. Status Register (Register Address 0x00)
Bit [0:3] [4] Default Value 0000 0 Type R R Name Unused TLOW 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 goes above the THIGH temperature limit. The bit clears to 0 when the status register is read and/or when the temperature measured goes back below the limit set in the THIGH - THYST setpoint registers. This bit is set to 1 when the temperature goes above the TCRIT temperature limit. This bit clears to 0 when the status register is read and/or when the temperature measured goes back 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 one-shot bits.
[5]
0
R
THIGH
[6]
0
R
TCRIT
[7]
1
R
RDY
Rev. 0 | Page 14 of 24
ADT7310
CONFIGURATION REGISTER
This 8-bit read/write register stores various configuration modes for the ADT7310, including shutdown, overtemperature and Table 8. Configuration Register (Register Address 0x01)
Bit [0:1] Default Value 00 Type R/W Name Fault queue 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 ADT7310. 00 = continuous conversion (default). When one conversion is finished, the ADT7310 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 0.0078125C.
undertemperature interrupts, one-shot, continuous conversion, interrupt pins polarity, and overtemperature fault queues.
[2]
0
R/W
CT pin polarity
[3]
0
R/W
INT pin polarity
[4]
0
R/W
INT/CT mode
[5:6]
00
R/W
Operation mode
[7]
0
R/W
Resolution
Rev. 0 | Page 15 of 24
ADT7310
TEMPERATURE VALUE 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. 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.
ID REGISTER
This 8-bit read-only register stores the manufacturer ID in Bit 7 to Bit 3 and the silicon revision in Bit 2 to Bit 0.
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 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.
[1]
0
R
THIGH flag/LSB1
[2]
0
R
TCRIT flag/LSB2
[3:7] [8:14] [15]
00000 0000000 0
R R R
Temp Temp Sign
Table 10. ID Register (Register Address 0x03)
Bit [2:0] [7:3] Default Value XXX 11000 Type R R Name Revision ID Manufacture ID Description Contains the silicon revision identification number. Contains the manufacturer identification number.
Table 11. TCRIT Setpoint Register (Register Address 0x04)
Bit [15:0] Default Value 0x4980 Type R/W Name TCRIT Description 16-bit critical overtemperature limit, stored in twos complement format.
Rev. 0 | Page 16 of 24
ADT7310
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. 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.
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 Table 12. THYST Setpoint Register (Register Address 0x05)
Bit [0:3] [4:7] Default Value 0101 0000 Type R/W R/W Name THYST N/A Description
Hysteresis value, from 0C to 15C. Stored in straight binary format. The default setting is 5C. Not used.
Table 13. THIGH Setpoint Register (Register Address 0x06)
Bit [0:15] Default Value 0x2000 Type R/W Name THIGH Description 16-bit overtemperature limit, stored in twos complement format.
Table 14. TLOW Setpoint Register (Register Address 0x07)
Bit [0:15] Default Value 0x0500 Type R/W Name TLOW Description 16-bit undertemperature limit, stored in twos complement format.
Rev. 0 | Page 17 of 24
ADT7310 SERIAL INTERFACE
VDD VDD PULL-UP VDD 10k 10k
ADT7310
MICROCONTROLLER SCLK DOUT DIN CS GND CT INT
0.1F
Figure 17. Typical SPI Interface Connection
The ADT7310 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 ADT7310 on the negative edge of SCLK, and data is clocked into the device on the positive edge of SCLK.
Bit C7 of the command byte must be set to 0 to successfully begin a bus transaction. The SPI interface does not work correctly if a 1 is written into this bit. 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. Bit C2 activates a continuous read mode on the temperature value register only. When this bit is set, the serial interface is configured so that the temperature value register can be continuously read. When the command word is 01010100 (0x54), the contents of the temperature value register can be read out without requiring repeated writes to set the address bits. Simply sending 16 SCLK clocks to the ADT7310 clocks the contents of the temperature value register onto the DOUT pin.
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 ADT7310 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 0 C6 R/W C5 C4 C3 Register address C2 Continuous read C1 0 C0 0
Rev. 0 | Page 18 of 24
07789-014
ADT7310
WRITING DATA
Data is written to the ADT7310 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 ADT7310 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.
CS
Figure 18 shows a write to an 8-bit register, and Figure 19 shows a write to a 16-bit register. The master must begin a new write transaction on the bus for every register write. Only one register is written to per bus transaction.
SCLK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
8-BIT COMMAND BYTE 0 DIN C7 R/W C6 REGISTER ADDR C5 C4 C3 CONT READ C2 0 C1 0 C0 D7 D6 D5
8-BIT DATA
D4
D3
D2
D1
D0
Figure 18. Writing to an 8-Bit Register
CS
SCLK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
22
23
07789-028
24
8-BIT COMMAND BYTE 0 DIN C7 R/W C6 REGISTER ADDR C5 C4 C3
CONT READ
16-BIT DATA 0 C1 0 C0 D15 D14 D13 D12 D11 D10 D9 D8 D7 D2 D1 D0
07789-029
C2
Figure 19. Writing to a 16-Bit Register
CS
SCLK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
8-BIT COMMAND WORD 0 DIN C7 R/W C6 REGISTER ADDR C5 C4 C3
CONT READ
0 C1
0 C0 8-BIT DATA D7 D6 D5 D4 D3 D2 D1 D0
07789-030
C2
DOUT
Figure 20. Read from an 8-Bit Register
Rev. 0 | Page 19 of 24
ADT7310
CS
SCLK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
22
23
24
8-BIT COMMAND BYTE
0 DIN C7 R/W C6
CONT REGISTER ADDR READ
C5 C4 C3 C2
0 C1
0 C0
16-BIT DATA
DOUT D15 D14 D13 D12 D11 D10 D9 D8 D7 D2 D1 D0
07789-031
Figure 21. Read from a 16-Bit Register
READING DATA
A read transaction begins when the master writes the command byte to the ADT7310 with the read/write bit set to 1. The master then supplies 8 or 16 clock pulses, depending on the addressed register, and the ADT7310 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 takes CS high. The master must begin a new read transaction on the bus for every register read. Only one register is read per bus transaction. However, in continuous read mode, Command Byte C2 = 1, and the temperature value register can be read from continuously. The master sends 16 clock pulses on SCLK, and the temperature value is clocked out on DOUT.
DSPs. SCLK can continue to run between data transfers, provided that the timing numbers are obeyed. 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 ADT7310 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 ADT7310 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.
INTERFACING TO DSPs OR MICROCONTROLLERS
The ADT7310 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
Rev. 0 | Page 20 of 24
ADT7310 INT AND CT OUTPUTS
The INT and CT pins are open drain outputs, and both pins require a 10 k pull-up resistor to VDD.
Comparator Mode
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. Putting the ADT7310 into shutdown mode does not reset the INT state in comparator mode.
UNDERTEMPERATURE AND OVERTEMPERATURE 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 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. Figure 22 illustrates the comparator and interrupt modes for events exceeding the THIGH limit with both pin polarity settings. Figure 23 illustrates the comparator and interrupt modes for events exceeding the TLOW limit with both pin polarity settings.
Interrupt Mode
In interrupt mode, the INT pin goes inactive when any ADT7310 register is read. Once 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 ADT7310 into shutdown mode resets the INT pin in the interrupt mode.
TEMPERATURE 82C 81C 80C 79C 78C 77C 76C 75C 74C 73C THIGH - THYST THIGH
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 TIME READ READ READ
Figure 22. INT Output Temperature Response Diagram for THIGH Overtemperature Events
Rev. 0 | Page 21 of 24
07789-020
ADT7310
TEMPERATURE -13C -14C -15C -16C -17C -18C -19C -20C -21C -22C TLOW TLOW + THYST
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 TIME READ READ READ
Figure 23. INT Output Temperature Response Diagram for TLOW Undertemperature Events
Rev. 0 | Page 22 of 24
07789-021
ADT7310 APPLICATIONS INFORMATION
THERMAL RESPONSE TIME
The time required for a temperature sensor to settle to a specified accuracy is a function of the thermal mass of the sensor and the thermal conductivity between the sensor and the object being sensed. Thermal mass is often considered equivalent to capacitance. Thermal conductivity is commonly specified using the symbol, Q, and can be thought of as thermal resistance. It is commonly specified in units of degrees per watt of power transferred across the thermal joint. The time required for the part to settle to the desired accuracy is dependent on the thermal contact established in that particular application, and the equivalent power of the heat source. In most applications, the settling time is best determined empirically.
TEMPERATURE MONITORING
The ADT7310 is ideal for monitoring the thermal environment within hazardous automotive applications. The die accurately reflects the exact thermal conditions that affect nearby integrated circuits. The ADT7310 measures and converts the temperature at the surface of its own semiconductor chip. When the ADT7310 is used to measure the temperature of a nearby heat source, the thermal impedance between the heat source and the ADT7310 must be considered. When the thermal impedance is determined, the temperature of the heat source can be inferred from the ADT7310 output. As much as 60% of the heat transferred from the heat source to the thermal sensor on the ADT7310 die is discharged via the copper tracks and the bond pads. Of the pads on the ADT7310, 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 ADT7310 GND pad and the GND of the heat source be reduced as much as possible.
SUPPLY DECOUPLING
The ADT7310 should be decoupled with a 0.1 F ceramic capacitor between VDD and GND. This is particularly important when the ADT7310 is mounted remotely from the power supply. Precision analog products, such as the ADT7310, require a wellfiltered power source. Because the ADT7310 operates from a single supply, it may seem convenient to tap into the digital logic power supply. Unfortunately, the logic supply is often a switch-mode design, which generates noise in the 20 kHz to 1 MHz range. In addition, fast logic gates can generate glitches hundreds of millivolts in amplitude due to wiring resistance and inductance. If possible, the ADT7310 should be powered directly from the system power supply. This arrangement, shown in Figure 24, 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. This decoupling capacitor must be placed as close as possible to the VDD pin of the ADT7310.
TTL/CMOS LOGIC CIRCUITS
0.1F
ADT7310
POWER SUPPLY
Figure 24. Use of Separate Traces to Reduce Power Supply Noise
Rev. 0 | Page 23 of 24
07789-022
ADT7310 OUTLINE DIMENSIONS
5.00 (0.1968) 4.80 (0.1890)
4.00 (0.1574) 3.80 (0.1497)
8 1
5 4
6.20 (0.2441) 5.80 (0.2284)
1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) COPLANARITY 0.10 SEATING PLANE
1.75 (0.0688) 1.35 (0.0532)
0.50 (0.0196) 0.25 (0.0099) 8 0 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157)
45
0.51 (0.0201) 0.31 (0.0122)
COMPLIANT TO JEDEC STANDARDS MS-012-A A 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.
Figure 25. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model ADT7310TRZ 2 ADT7310TRZ-REEL2 ADT7310TRZ-REEL72 EVAL-ADT7310EBZ2
1 2
Temperature Range -55C to +150C -55C to +150C -55C to +150C
Temperature Accuracy 1 0.5C 0.5C 0.5C
Package Description 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N Evaluation Board
012407-A
Package Option R-8 R-8 R-8
Maximum accuracy over the -40C to +105C temperature range. Z = RoHS Compliant Part.
(c)2009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D07789-0-4/09(0)
Rev. 0 | Page 24 of 24

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