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±1°C Accurate, 13-Bit, Digital Temperature Sensor ADT7301 Rev. B 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. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2005–2011 Analog Devices, Inc. All rights reserved.
FEATURES
13-bit temperature-to-digital converter −40°C to +150°C operating temperature range ±0.5°C typical accuracy 0.03125°C temperature resolution Shutdown current of 1 μA Power dissipation of 0.631 mW at V DD = 3.3 V SPI- and DSP-compatible serial interface Shutdown mode Space-saving SOT-23 and MSOP packages Compatible with AD7814
APPLICATIONS
Figure 1. GENERAL DESCRIPTION The ADT7301 is a complete temperature monitoring system available in SOT-23 and MSOP packages. It contains a band gap temperature sensor and a 13-bit ADC to monitor and digitize the temperature reading to a resolution of 0.03125°C. The ADT7301 has a flexible serial interface that allows easy interfacing to most microcontrollers. The interface is compati- ble with SPI®, QSPI™, and MICROWIRE™ protocols as well as DSPs. The part features a standby mode that is controlled via the serial interface. The ADT7301’s wide supply voltage range, low supply current, and SPI-compatible interface make it ideal for a variety of applications including personal computers, office equipment, automotive, and domestic appliances. The ADT7301 is rated for operation over the −40°C to +150°C temperature range. It is not recommended to operate the device at temperatures above +125°C for greater than a total of 5% (5,000 hours) of the lifetime of the device. Exposure beyond this limit affects device reliability. PRODUCT HIGHLIGHTS 1. On-chip temperature sensor that allows an accurate measurement of the ambient temperature. The measurable temperature range is −40°C to +150°C. 2. Supply voltage of 2.7 V to 5.25 V . 3. Space-saving 6-lead SOT-23 and 8-lead MSOP packages. 4. Typical temperature accuracy of ±0.5°C. 5. 13-bit temperature reading to 0.03125°C resolution. 6. Shutdown mode that reduces the power consumption to 4.88 μW with V DD = 3.3 V @ 1 SPS. 7. Compatible with AD7814.
ADT7301* PRODUCT PAGE QUICK LINKS Last Content Update: 02/23/2017 COMPARABLE PARTS View a parametric search of comparable parts. EVALUATION KITS
- ADT7301 Evaluation Board DOCUMENTATION Application Notes
- AN-892: Temperature Measurement Theory and Practical Techniques Data Sheet
- ADT7301: ±1°C Accurate, 13-Bit, Digital Temperature Sensor Data Sheet DESIGN RESOURCES
- ADT7301 Material Declaration
- PCN-PDN Information
- Quality And Reliability
- Symbols and Footprints DISCUSSIONS View all ADT7301 EngineerZone Discussions. SAMPLE AND BUY Visit the product page to see pricing options. TECHNICAL SUPPORT Submit a technical question or find your regional support number. DOCUMENT FEEDBACK Submit feedback for this data sheet. This page is dynamically generated by Analog Devices, Inc., and inserted into this data sheet. A dynamic change to the content on this page will not trigger a change to either the revision number or the content of the product data sheet. This dynamic page may be frequently modified.
Rev. B | Page 2 of 16 TABLE OF CONTENTS
REVISION HISTORY
6/11—Rev. A to Rev. B Changed Temperature Conversion Time from 800 µs to 1.2 ms .. 3 Changed Temperature Conversion Time in Converter 3/10—Rev. 0 to Rev. A 10/05—Revision 0: Initial Version
TA = TMIN to TMAX, VDD = 2.7 V to 5.25 V , unless otherwise noted. All specifications are for −40°C to +150°C, unless otherwise noted. Table 1. A Grade Specifications 1 The accuracy specifications for 0°C to 70°C are specified to 3.5-Σ performance. beyond this limit affects device reliability. from 0°C to 100°C, it would take typically 2 seconds for the ADT7301 to reach 63.2°C. complete, the ADT7301 is put back into shutdown mode. 5 Guaranteed by design and characterization, not production tested.
1 See Figure 14 for the SPI timing diagram. 2 Measured with the load circuit of Figure 2. Figure 2. Load Circuit for Data Access Time and Bus Relinquish Time
1 It is not recommended to operate the ADT7301 at temperatures above
device. Any exposure beyond this limit affects device reliability.
4 Junction-to-case resistance is applicable to components featuring a
Figure 3. Plot of Maximum Power Dissipation vs. Temperature
Rev. B | Page 9 of 16 THEORY OF OPERATION The ADT7301 is a 13-bit digital temperature sensor with a 14th bit that acts as a sign bit. The part houses an on-chip temperature sensor, a 13-bit A/D converter, a reference circuit, and serial interface logic functions in SOT-23 and MSOP packages. The ADC section consists of a conventional successive approximation converter based around a capacitor DAC. The parts run on a 2.7 V to 5.25 V power supply. The on-chip temperature sensor allows an accurate measure- ment of the ambient device temperature to be made. The specified measurement range of the ADT7301 is −40°C to +150°C. Greater than 125°C, the ADT7301 is limited to 5% of its 55°C operational lifetime. The structural integrity of the device may start to deteriorate when continuously operated at absolute maximum voltage and temperature specifications. CONVERTER DETAILS The conversion clock for the part is internally generated. No external clock is required except when reading from and writing to the serial port. In normal mode, an internal clock oscillator runs an automatic conversion sequence. During this automatic conversion sequence, a conversion is initiated every 1.5 second. At this time, the part powers up its analog circuitry and performs a temperature conversion. This temperature conversion typically takes 1.2 ms, after which the analog circuitry of the part auto- matically shuts down. The analog circuitry powers up again when the 1.5 second timer times out and the next conversion begins. Since the serial interface circuitry never shuts down, the result of the most recent temperature conversion is always available in the serial output register. The ADT7301 can be placed into shutdown mode via the control register. This means that the on-chip oscillator is shut down and no further conversions are initiated until the ADT7301 is taken out of shutdown mode. The ADT7301 can be taken out of shutdown mode by writing all 0s into the control register. The conversion result from the last conversion prior to shutdown can still be read from the ADT7301 even when it is in shutdown mode. In normal conversion mode, the internal clock oscillator is reset after every read or write operation. This causes the device to start a temperature conversion, the result of which is typically available 1.2 ms later. Similarly, when the part is taken out of shutdown mode, the internal clock oscillator is started and a conversion is initiated. The conversion result is available 1.2 ms later. Every result is stored in a buffer register and is loaded into the temperature value register only at the first falling SCLK edge of every serial port activity. Serial port activity does not interfere with conversion processes, and every conversion is completed, even during a read operation. A conversion has to be completed before a read occurs, otherwise its result is not loaded into the temperature value register and instead is loaded into the buffer register. A new conversion is triggered at the end of each serial port activity, except when a conversion is already in progress.
typical performance curve is shown in Figure 11. Table 5. Temperature Data Format Figure 13. Temperature-to-Digital Transfer Function 1 ADC code uses all 14 bits of the data byte, including the sign bit. 2 DB13 (the sign bit) is removed from the ADC code.
Rev. B | Page 13 of 16 The following software program shows how to program a PIC16F873 to communicate with the ADT7301. The PIC16F873 is configured as an SPI master with the Port A.1 pin used as CS . Any microchip microcontroller can use this program by simply exchanging the include file for the device that is being used. #include <16F873.h> #device adc = 8 #use delay(clock = 4000000) #fuses NOWDT,XT, PUT, NOPROTECT, BROWNOUT, LVP #BIT CKP = 0x14.4 #define CS PIN_A1 void main(){ int MSByte,LSByte; long int ADC_Temp_Code; float TempVal,ADC_Temp_Code_dec; setup_spi(spi_master); //Pic is set up as master device. CKP = 1; //Idle state of clock is high. do{ delay_ms(10); //Allow time for conversions. Output_low(CS); //Pull CS low. delay_us(10); //CS to SCLK set-up time. MSByte = SPI_Read(0); //The first byte is clocked in. LSByte = SPI_Read(0); //The second byte is clocked in. delay_us(10); //SCLK to CS set-up time. Output_High(CS); //Bring CS high. ADC_Temp_Code = make16(MSByte,LSByte); //16 bit ADC code is stored ADC_Temp_Code. ADC_Temp_Code_dec = (float)ADC_Temp_Code; //Convert to float for division. if ((0x2000 & ADC_Temp_Code) == 0x2000) //Check sign bit for negative value. TempVal = (ADC_Temp_Code_de c - 16384)/32; //Conversion formula if negative temperature. else TempVal = (ADC_Temp_Code_dec/32); //Conversion formula if positive temperature. }while(True); //Temperature value stored in TempVal.
0.95 BSC
0.15 MAX
0.05 MIN
1.45 MAX
0.95 MIN
0.20 MAX
0.08 MIN
0.50 MAX
0.30 MIN
Figure 19. 6-Lead Small Outline Transistor Package [SOT-23]
0.65 BSC
1.10 MAX
Figure 20. 8-Lead Mini Small Outline Package [MSOP] 2 Temperature accuracy is over a 0°C to 70°C temperature range.
Rev. B | Page 16 of 16 NOTES ©2005–2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D02884–0–6/ 1 1(B)