LM95172

LM95172 13-Bit to 16-Bit 200°C Digital Temp Sensor with 3-Wire Interface December 16, 2009 LM95172 13-Bit to 16-Bit 200°C Digital Temp Sensor with 3-Wire Interface General Description The LM95172EWG is an integrated digital-output temperature sensor with a Serial Peripheral Interface (SPI) and MICROWIRE™-compatible interface in a 10-pin Cerpack high temperature ceramic package. It features a very linear SigmaDelta Analog-to-Digital Converter (ADC), high accuracy, fast conversion rates, and extremely low output noise. With an operating temperature as low as -40°C and optimized accuracy from 120°C to 200°C, it is ideal for high-temperature applications. The over-temperature alarm output (OVERTEMP) asserts when the die temperature exceeds a programmed THIGH limit. The user-programmed TLOW limit creates a temperature-stabilizing hysteresis when the ambient temperature is near the trip point. The LM95172EWG can be programmed to operate from 13 bits (0.0625°C per LSB) to 16 bits (0.0078125°C per LSB) resolution. The LM95172EWG powers up in 35 ms, the fastest conversion time, with temperature output set at 13-bit resolution. The resolution may then be changed to 14-, 15- or 16-bits. When in the 13-, 14- or 15-bit resolution mode, the least significant bit in the 16-bit temperature register toggles after the completion of each conversion. This bit may be monitored to verify that the conversion is complete. The high noise immunity of the Serial I/O (SI/O) output makes the LM95172EWG ideal for use in challenging electromagnetic environments. Features ■ LM95172EWG is AEC-Q100 Grade 0 qualified and is manufactured on an Automotive Grade Flow. ■ 13-bit (0.0625°C LSB) to 16-bit (0.0078125°C LSB) ■ ■ ■ ■ temperature resolution Wide −40°C to +200°C temperature range 35 ms best conversion time tracks fast temp changes OVERTEMP digital output switches when TDIE > THIGH Shutdown mode saves power yet wakes up for one-shot temperature update ■ SPI and MICROWIRE Bus interface ■ 10-Pin Cerpack high-temperature ceramic package Key Specifications ■ Analog and Digital Supply Voltage ■ Total Supply Current     Operating Shutdown −40°C to +140°C Shutdown −40°C to +175°C Shutdown −40°C to +200°C ■ Temperature Accuracy +175°C to +200°C +130°C to +160°C +120°C to +130°C +160°C to +175°C −40°C to +120°C 3.0V to 5.5V 400 µA (typ) 4 µA (max) 12 µA (max) 28 µA (max) ±3.0°C (max) ±1.0°C (max) ±2.0°C (max) ±2.0°C (max) ±3.5°C (max) Applications ■ ■ ■ ■ ■ Automotive high temperature applications Industrial Power Controllers Industrial motors, gear boxes Geothermal instrumentation High Temperature Test Equipment ■ Temperature Resolution 13-bit mode 0.0625°C/LSB 16-bit mode 0.0078125°C/LSB ■ Conversion Time 13-bit mode 16-bit mode 43 ms (max) 350 ms (max) Connection Diagram LM95172EWG Top View 30076602 MICROWIRE™ is a trademark of National Semiconductor Corporation. TRI-STATE® is a registered trademark of National Semiconductor Corporation. © 2009 National Semiconductor Corporation 300766 www.national.com LM95172 Pin Descriptions Pin Number 1 2 3 4 5 6 7 8 9 10 Name OVERTEMP SC NC CS GND NC SI/O NC VDD ANALOG VDD IO Type Output Input N/A Input Ground N/A Description OVERTEMP Alarm Serial Clock input No Connect Chip Select input Power Supply Ground No Connect Typical Connection Over-temperature Alarm Output, Open-drain. Active Low on POR. Requires a pull-up resistor to VDD IO. Serial clock from the Controller Do not connect to this pin. Chip Select input for the bus. Low pass filtered. Ground Do not connect to this pin. Serial I/O Data line to or from the Controller Do not connect to this pin. DC Voltage from 3.0V to 5.5V. Bypass with a 10 nF ceramic capacitor near the pad to ground. DC Voltage from 3.0V to 5.5V. Bypass with a 10 nF ceramic capacitor near the pin to ground. Bidirectio Serial I/O nal N/A Power Power No Connect Analog Power Supply Voltage Digital Power Supply Voltage Simplified Block Diagram 30076601 Ordering Information Order Number LM95172EWG NS Package Number WG10A Transport Media 54 units in tray www.national.com 2 LM95172 Typical Application 30076603 FIGURE 1. Microcontroller Interface - normal connection 3 www.national.com LM95172 Absolute Maximum Ratings (Note 1) VDD ANALOG and VDD IO Supply Voltages Voltage at any Pin Input Current at any Pin Storage Temperature Soldering Information Infrared or Convection (20 sec.) ESD Susceptibility (Note 7) Human Body Model Machine Model Charged Device Model −0.2V to 6.0V −0.2V to (VDD IO + 0.2V) 5 mA −65°C to +175°C Operating Ratings Specified Temperature Range Analog Supply Voltage Range VDD ANALOG Digital Supply Voltage Range VDD IO −40°C to +200°C +3.0V to +5.5V +3.0V to +5.5V Package Thermal Resistances 235°C 2500 V 250 V 1000 V Package 10-Lead CERPACK θJA 175°C/W Temperature-to-Digital Converter Characteristics Unless otherwise noted, these specifications apply for VDD ANALOG = VDD IO = 3.0V to 3.6V.(Note 8) Boldface limits apply for TA =−40°C to +200°C; all other limits TA = 25°C, unless otherwise noted. Parameter Conditions TA = +175°C to +200°C Temperature Accuracy (Note 8) TA = +130°C to +160°C TA = +120°C to +130°C TA = +160°C to +175°C TA = −40°C to +120°C Res 1 Bit 0 0 Resolution 1 1 Res 0 Bit 13 0.0625 14 0.03125 15 0.015625 16 0.0078125 43 87 175 350 TA = −40°C to 140°C Bus Inactive Continuous Conversion Mode Total Quiescent Current (Note 9) Shutdown Mode TA = −40°C to 175°C TA = −40°C to 200°C TA = −40°C to 140°C TA = −40°C to 175°C TA = −40°C to 200°C 28 500 400 456 510 650 4 12 75 ms (max) Typical (Note 3) LM95172EWG Limits (Note 2) ±3.0 ±1.0 ±2.0 ±2.0 ±3.5 Bits °C Bits °C Bits °C Bits °C °C (max) Units (Limit)  0  1  0  1 For 13 Bits Resolution Temperature Conversion Time For 15 Bits Resolution For 16 BIts Resolution For 14 Bits Resolution μA (max) www.national.com 4 LM95172 Parameter Conditions Typical (Note 3) LM95172EWG Limits (Note 2) 0.9 2.1 0.8 2.1 0.3 2.1 Units (Limit) V (min) V (max) V (min) V (max) V (min) V (max) TA = −40°C to 140°C Power-On Reset TA = −40°C to 175°C Threshold TA = −40°C to 200°C 5 www.national.com LM95172 Logic Electrical Characteristics Digital DC Characteristics Unless otherwise noted, these specifications apply for VDD ANALOG = VDD IO = 3.0V to 3.6V. (Note 8). Boldface limits apply for TA = -40°C to 200°C; all other limits TA = +25°C, unless otherwise noted. Symbol VIH VIL Parameter Logical "1" Input Voltage Logical "0" Input Voltage VDD IO = 3.0V VDD IO = 3.3V VHYST Digital Input Hysteresis VDD IO = 3.6V VDD IO = 4.5V VDD IO = 5.0V VDD IO = 5.5V IIH IIL VOH VOL Logical “1” Input Leakage Current Logical “0” Input Current Output High Voltage Output Low Voltage OVERTEMP Output Saturation Voltage VIN = VDD IO VIN = 0V IOH = 100 μA (Source) IOH = 2 mA (Source) IOL = 100 μA (Sink) IOL = 2 mA (Sink) IOL = 2 mA (Sink) 0.63 0.79 0.97 Conditions Typical (Note 3) Limits (Note 2) 0.75×VDD IO 0.25×VDD IO 0.42 0.56 0.72 0.9 1.0 1.1 1 −1 VDD IO − 0.2 VDD IO − 0.45 0.2 0.45 0.45 V(max) V (max) μA (max) μA (max) V (min) Units (Limit) V (min) V (max) V (min) www.national.com 6 LM95172 Serial Bus Digital Switching Characteristics Unless otherwise noted, these specifications apply for VDD ANALOG = VDD IO = 3.0V to 3.6V (Note 8); CL (load capacitance) on output lines = 100 pF unless otherwise specified. Boldface limits apply for TA = -40°C to 200°C; all other limits TA = +25°C, unless otherwise noted. Symbol t1 t2 t3 t4 t5 t6 t7 t8 tTA tBUF SC (Serial Clock) Period CS (Chip Select) Low to SC High Set-Up Time (Note 5) CS Low to SI/O Output Delay (Note 5) SC Low to SI/O Output Delay CS High to Data Out (SI/O) TRI-STATE SC High to SI/O Input Hold Time SI/O Input to SC High Set-Up Time SC Low to CS High Hold Time Data Turn-Around Time: SI/O input (write to LM95172EWG) to output (read from LM95172EWG) Bus free time between communications: CS High to CS Low. (Note 5) Parameter Typical (Note 3) Limits (Note 2) 765 1.25 1 120 220 50 30 50 130 5 Units (Limit) ns (min) µs (min) µs (max) ns (max) ns (max) ns (min) ns (min) ns (min) ns (max) µs (min) 30076604 FIGURE 2. Data Output Timing Diagram 30076605 FIGURE 3. TRI-STATE Data Output Timing Diagram 7 www.national.com LM95172 30076606 FIGURE 4. Data Input Timing Diagram 30076609 FIGURE 5. tBUF Timing Definition Diagram 30076610 FIGURE 6. tTA Timing Definition Diagram Note 1: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability and/or performance. Functional operation of the device and/or non-degradation at the Absolute Maximum Ratings or other conditions beyond those indicated in the Operating Ratings is not implied. The Operating Ratings indicate conditions at which the device is functional and the device should not be operated beyond such conditions. Note 2: The Electrical characteristics tables list guaranteed specifications under the listed Operating Ratings except as otherwise modified or specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations only and are not guaranteed. Note 3: Typical values represent most likely parametric norms at specific conditions (Example Vcc; specific temperature) and at the recommended Operating Conditions at the time of product characterizations and are not guaranteed. Note 4: Specification is guaranteed by characterization and is not tested in production Note 5: Specification is guaranteed by design and is not tested in production Note 6: Invalid. The LM95172EWG will return a "0" if read. If written to, no valid register will be modified. Note 7: Human body model, 100 pF discharged through a 1.5 kΩ resistor. Machine model, 200 pF discharged directly into each pin. The Charged Device Model (CDM) is a specified circuit characterizing an ESD event that occurs when a device acquires charge through some triboelectric (frictional) or electrostatic induction processes and then abruptly touches a grounded object or surface. Note 8: The LM95172EWG will operate properly over the VDD ANALOG = 3.0V to 5.5V and VDD IO = 3.0V to 5.5V supply voltage ranges. Note 9: Total Quiescent Current includes the sum of the currents into the VDD ANALOG and the VDD IO pins. Note 10: This specification is provided only to indicate how often temperature data is updated. The LM95172EWG can be read at any time without regard to conversion state (and will yield last conversion result). A conversion in progress will not be interrupted. The output shift register will be updated at the completion of the read and a new conversion restarted. www.national.com 8 LM95172 TRI-STATE Test Circuit 30076607 FIGURE 7. 1.0 Functional Description The LM95172EWG temperature sensor incorporates a temperature sensor and a 13-bit to 16-bit ΣΔ ADC (Sigma-Delta Analog-to-Digital Converter). Compatibility of the LM95172EWG's three wire serial interface with SPI and MI- CROWIRE allows simple communications with common microcontrollers and processors. Shutdown mode can be used to optimize current drain for different applications. A Manufacturer's/Device ID register identifies the LM95172EWG as National Semiconductor product. See Figure 8 for the Functional Block Diagram. 30076622 FIGURE 8. LM95172EWG Functional Block Diagram 9 www.national.com LM95172 1.1 INITIAL SOFTWARE RESET AND POWER-UP SEQUENCES AND POWER ON RESET (POR) 1.1.1 Software Reset Sequence A software reset sequence must be followed, after the initial VDD ANALOG and VDD IO supply voltages reach their specified minimum operating voltages, in order to ensure proper operation of the LM95172EWG. The software reset sequence is as follows: 1. Allow VDD ANALOG and VDD IO to reach their specified minimum operating voltages, as specified in the Operating Ratings section, and in a manner as specified in section 1.1.2 below. 2. Write a “1” to the Shutdown bit, Bit 15 of the Control/Status Register, and hold it high for at least the specified maximum conversion time for the initial default of 13-bits resolution, in order to ensure that a complete reset operation has occurred. (See the Temperature Conversion Time specifications within the Temperature-to-Digital Characteristics section.) 3. Write a “0” to the Shutdown bit to restore the LM95172EWG to normal mode. 4. Wait for at least the specified maximum conversion time for the initial default of 13-bits resolution in order to ensure that accurate data appears in the Temperature Register. 1.1.2 Power-Up Sequence Warning: In all cases listed below the VDD ANALOGwaveform must not lag the VDD IOwaveform B. Resistor-Capacitor (R-C) Charging Exponential Power-up In the case where the VDD ANALOG and VDD IO voltage-vs.-time function is as a typical R-C Charging exponential function the time constant must be less than or equal to 1.25 ms. C. Other Power-up Functions In the case where the VDD ANALOG and VDD IO voltage-vs.-time characteristic follows another function the following requirements must be met: (1) The specified minimum operating voltage values for VDD ANALOG and VDD IO must be reached in 5 ms or less. (2) The slope of the VDD ANALOG and VDD IO power-up curves must be greater than or equal to 0.7 V/ms at any time before the specified minimum operating voltage is reached. (3) The slope of the VDD ANALOG and VDD IO power-up curves must not allow ringing such that the voltage is allowed to drop below the specified minimum operating voltage at any time after the specified minimum operating voltage is reached. 1.1.3 Power On Reset (POR) After the requirements of section 1.1.1 and 1.1.2 above are met each register will then contain its defined POR default value. Any of the following actions may cause register values to change from their POR value: 1. The master writes different data to any Read/Write (R/W) bits, or 2. The LM95172EWG is powered down. The specific POR Value of each register is listed in Section 1.7 under Internal Register Structure. A. Linear Power-up In the case where the VDD ANALOG and VDD IO voltage-vs.-time function is linear, the specified minimum operating voltage must be reached in 5 ms or less. www.national.com 10 LM95172 1.2 ONE SHOT CONVERSION The LM95172EWG features a one-shot conversion bit, which is used to initiate a singe conversion and comparison cycle when the LM95172EWG is in shutdown mode. While the LM95172EWG is in shutdown mode, writing a "1" to the OneShot bit in the Control/Status Register will cause the LM95172EWG to perform a single temperature conversion and update the Temperature Register and the affected status bits. Operating the LM95172EWG in this one-shot mode allows for extremely low average-power comsumption, making it ideal for low-power applications. When the One-shot bit is set, the LM95172EWG initiates a temperature conversion. After this initiation, but before the completion of the conversion, and resultant register updates, the LM95172EWG is in a "one-shot" state. During this state, the Data Available (DAV) flag in the Control/Status Register is "0" and the Temperature Register contains the value 8000h (-256°C). All other registers contain the data that was present before initiating the one-shot conversion. After the temperature measurement is complete, the DAV flag will be set to "1" and the temperature register will contain the resultant measured temperature. 1.3 OVERTEMP OUTPUT The Over-temperature (OVERTEMP) output is a temperature switch signal that indicates when the measured temperature exceeds the THIGH programmed limit. The programmable THIGH register sets the high temperature limit and the TLOW register is used to set the hysteresis. The TLOW register also sets the temperature below which the OVERTEMP output resets. The OVERTEMP output of the LM95172EWG behaves as a temperature comparator. The following explains the operation of OVERTEMP. Figure 9 illustrates the OVERTEMP output behavior. 30076621 FIGURE 9. LM95172EWG OVERTEMP vs. Temperature Response Diagram The OVERTEMP Output will assert when the measured temperature is greater than the THIGH value. OVERTEMP will reset if any of the following events happen: 1. The temperature falls below the value stored in the TLOW register, or 2. A "1" is written to the OVERTEMP Reset bit in the Control/ Status Register. If OVERTEMP is cleared by the master writing a "1" to the OVERTEMP Reset bit while the measured temperature still exceeds the THIGH value, OVERTEMP will assert again after the completion of the next temperature conversion. Placing the LM95172EWG in shutdown mode or triggering a one-shot conversion does not cause OVERTEMP to reset. 11 www.national.com LM95172 1.4 COMMUNICATING WITH THE LM95172EWG The serial interface consists of three lines: CS (Chip Select), SC (Serial Clock), and the bi-directional SI/O (Serial I/O) data line. A high-to-low transition of the CS line initiates the communication. The master (processor) always drives the chip select and the clock. The first 16 clocks shift the temperature data out of the LM95172EWG on the SI/O line (a temperature read). Raising the CS at anytime during the communication will terminate this read operation. Following this temperature read, the SI/O line becomes an input and a command byte can be written to the LM95172EWG. This command byte contains a R/W bit and the address of the register to be communicated with next (see Section 1.7 Internal Register Structure). When writing, the data is latched in after every 8 bits. The processor must write at least 8 bits in order to latch the data. If CS is raised before the falling edge of the 8th command bit, no data will be latched into the command byte. If CS is raised after the 8th bit, but before the 16th bit, of a write to a 16-bit data register, only the most significant byte of the data will be latched. This command-data-command-data sequence may be performed as many times as desired. 30076614 FIGURE 10. Reading the Temperature Register 30076616 FIGURE 11. Reading the Temperature Register followed by a read or write from another register (Control/Status, THIGH, TLOW, or Identification register) 30076615 FIGURE 12. Reading the Temperature Register followed by repeated commands and Data Register accesses (Control/ Status, THIGH, TLOW, or Identification register) www.national.com 12 LM95172 1.5 TEMPERATURE DATA FORMAT Temperature data is represented by a 13- to 16-bit, two's complement word with a Least Significant Bit (LSB) equal to 0.0625 °C (13-bits), 0.03125 °C (14-bits), 0.015625 °C (15bits) or 0.0078125 °C (16-bits). See Section 1.7.2 for definition of the bits in the Temperature Register. 13-Bit Resolution. First Bit (D15) is Sign, the last bit (D0) is Toggle and bits D1 and D2 are always 0. 13-bit Resolution Digital Output Temperature 16-bit Binary 0101011110000 000 0101011110000 001 0100101100000 000 0100101100000 001 0010100000000 000 0010100000000 001 0000110010000 000 0000110010000 001 0000000000001 000 0000000000001 001 0000000000000 000 0000000000000 001 1111111111111 000 1111111111111 001 1110110000000 000 1110110000000 001 All 16 Bits Hex 5780 5781 4B00 4B01 2800 2801 0C80 0C81 0008 0009 0000 0001 FFF8 FFF9 EC00 EC01 Bits D15 - D3 Hex 0AF0 0960 0500 0190 0001 0000 1FFF 1D80 +175°C +150°C +80°C +25°C +0.0625°C 0°C −0.0625°C −40°C 14-Bit Resolution. First bit (D15) is Sign, the last bit (D0) is Toggle and bit D1 is always 0. 14-bit Resolution Digital Output Temperature 16-bit Binary 01010111100000 00 01010111100000 01 01001011000000 00 01001011000000 01 00101000000000 00 00101000000000 01 00001100100000 00 00001100100000 01 00000000000001 00 00000000000001 01 00000000000000 00 00000000000000 01 11111111111111 00 11111111111111 01 11101100000000 00 11101100000000 01 All 16 Bits Hex 5780 5781 4B00 4B01 2800 2801 0C80 0C81 0004 0005 0000 0001 FFFC FFFD EC00 EC01 Bits D15 - D2 Hex 15E0 12C0 0A00 0320 0001 0000 3FFF 3B00 +175°C +150°C +80°C +25°C +0.03125°C 0°C −0.03125°C −40°C 13 www.national.com LM95172 15-Bit Resolution. First bit (D15) is Sign and the last bit (D0) is Toggle. 15-bit Resolution Digital Output Temperature 16-bit Binary 010101111000000 0 010101111000000 1 010010110000000 0 010010110000000 1 001010000000000 0 001010000000000 1 000011001000000 0 000011001000000 1 000000000000001 0 000000000000001 1 000000000000000 0 000000000000000 1 111111111111111 0 111111111111111 1 111011000000000 0 111011000000000 1 All 16 Bits Hex 5780 5781 4B00 4B01 2800 2801 0C80 0C81 0002 0003 0000 0001 FFFE FFFF EC00 EC01 Bits D15 - D1 Hex 2BC0 2580 1400 0640 0001 0000 7FFF 7600 +175°C +150°C +80°C +25°C +0.015625°C 0°C −0.015625°C −40°C 16-Bit Resolution. First bit (D15) is Sign and the last bit (D0) is the LSB. 16-bit Resolution Digital Output Temperature +175°C +150°C +80°C +25°C +0.0078125°C 0°C −0.0078125°C −40°C 16-bit Binary 0101 0111 1000 0000 0100 1011 0000 0000 0010 1000 0000 0000 0000 1100 1000 0000 0000 0000 0000 0001 0000 0000 0000 0000 1111 1111 1111 1111 1110 1100 0000 0000 All 16 Bits Hex 5780 4B00 2800 0C80 0001 0000 FFFF EC00 The first data byte is the most significant byte with most significant bit first, permitting only as much data as necessary to be read to determine temperature condition. For instance, if the first four bits of the temperature data indicate an overtemperature condition, the host processor could immediately take action to remedy the excessive temperatures. 1.6 SHUTDOWN MODE Shutdown Mode is enabled by writing a “1” to the Shutdown Bit, Bit 15 of the Control/Status Register, and holding it high for at least the specified maximum conversion time at the ex- isting temperature resolution setting. (see Temperature Conversion Time specifications under the Temperature-to-Digital Characteristics section). For example, if the LM95172EWG is set for 16-bit resolution before shutdown, then Bit 15 of the Control/Status register must go high and stay high for the specified maximum conversion time for 16-bits resolution. The LM95172EWG will always finish a temperature conversion and update the temperature registers before shutting down. Writing a “0” to the Shutdown Bit restores the LM95172EWG to normal mode. www.national.com 14 LM95172 1.7 INTERNAL REGISTER STRUCTURE The LM95172EWG has four registers that are accessible by issuing a command byte (a R/W Bit plus the register address: Control/ Status, THIGH, TLOW, and Identification. Which of these registers will be read or written is determined by the Command Byte. See Section 1.4, "Communicating with the LM95172EWG", for a complete description of the serial communication protocol. The following diagram describes the Command Byte and lists the addresses of the various registers. On power-up, the Command Byte will point to the Temperature Register by default. The temperature is read by lowering the CS line and then reading the 16-Bit temperature register; all other registers are accessed by writing a Command Byte after reading the temperature. All registers can be communicated with, either in Continuous Conversion mode or in Shutdown mode. When the LM95172EWG has been placed in Shutdown Mode, the Temperature register will contain the temperature data which resulted from the last temperature conversion (whether it was the result of a continuous-conversion reading or a one-shot reading). 1.7.1 Command Byte P7 R/W P6 0 P5 0 P4 0 P3 0 P2 P1 P0 Register Select Bit Read/Write Bit. Tells the LM95172EWG if the host will be writing to, or reading from, the register to which this byte is pointing. Bits Not Used. These Bits must be zero. If an illegal address is written, the LM95172EWG will return 0000h on the subsequent read. Bits Pointer Address Bits. Points to desired register. See table below. P2 0 0 0 0 1 1 1 1 Power-On Reset state: 00h Reset Conditions: Upon Power-on Reset 1.7.2 Temperature Register (Read Only): Default Register D15 Sign D7 1°C D6 0.5°C D5 0.25°C D14 128°C D4 0.125°C D13 64°C D3 0.0625°C D12 32°C D11 16°C D2 0.03125°C D10 8°C D1 0.015625°C D9 4°C D8 2°C D0 Conversion - Toggle/ 0.0078125°C P1 0 0 1 1 0 0 1 1 P0 0 1 0 1 0 1 0 1 Identification Invalid. (Note 6) Register Invalid. (Note 6) Control/Status THIGH TLOW Bit : Temperature Data Byte. Reperesents the temperature that was measured by the most recent temperature conversion in two's complement form. On power-up, this data is invalid until the DAV Bit in the Control/Status Register is high (that is, after completion of the first conversion). The resolution is user-programmable from 13-Bit resolution (0.0625°C) through 16-Bit resolution (0.0078125°C). The desired resolution is programmed through Bits 4 and 5 of the Control/Status Register. See the description of the Control/Status Register for details on resolution selection. The Bits not used for a selected resolution are always set to "0" and are not to be considered part of a valid temperature reading. For example, for 14-Bit resolution, Bit is not used and, therefore, it is invalid and is always zero. Bit : Conversion Toggle or, if 16-Bit resolution has been selected, this is the 16-Bit temperature LSB. When in 13-Bit, 14-Bit, or 15-Bit resolution mode, this Bit toggles each time the Temperature register is read if a conversion has completed since the last read. If conversion has not completed, the value will be the same as the last read. 15 www.national.com LM95172 When in 16-Bit resolution mode, this is the Least Significant Bit of the temperature data. Reset Conditions: See Sections 1.1.1 through 1.1.3 for reset conditions. One-Shot State: 8000h (-256°C) 1.7.3 Control/Status Register (Read/Write) Pointer Address: 81h (Read); 01h (Write) D15 SD D14 One-Shot D13 OVERTEMP Reset D6 OVERTEMP POL D5 RES1 D12 Conversion Toggle D4 RES0 D11 OVERTEMP Status D3 0 D10 THIGH D9 TLOW D8 DAV D7 OVERTEMP Disable D2 reserved D1 reserved D0 0 Bit : Shutdown (SD) Bit. Writing a “1” to this bit and holding it high for at least the specified maximum conversion time, at the existing temperature resolution setting, enables the Shutdown Mode. Writing a “0” to this bit restores the LM95172EWG to normal mode. Bit : One-Shot Bit. When in shutdown mode (Bit is "1"), initates a single temperature conversion and update of the temperature register with new temperature data. Has no effect when in continuous conversion mode (i.e., when Bit is "0"). Always returns a "0" when read. Bit : OVERTEMP Reset Bit. Writing a "1" to this Bit resets the OVERTEMP Status bit and, after a possible wait up to one temperature conversion time, the OVERTEMP pin. It will always return a "0" when read. Bit : Conversion Toggle Bit. Toggles each time the Control/Status register is read if a conversion has completed since the last read. If conversion has not been completed, the value will be the same as last read. Bit : OVERTEMP Status Bit. This Bit is "0" when OVERTEMP output is low and "1" when OVERTEMP output is high. The OVERTEMP output is reset under the following conditions: (1) Cleared by writing a "1" to the OVERTEMP Reset Bit (Bit ) in this register or (2) Measured temperature falls below the TLOW limit. If the temperature is still above THIGH, and OVERTEMP Reset is set to "1", then the Bit and the pin clear until the next conversion, at which point the Bit and pin would assert again. Bit : Temperature High (THIGH) Flag Bit. This Bit is set to "1" when the measured temperature exceeds the THIGH limit stored in the programmable THIGH register. The flag is reset to "0" when both of two conditions are met: (1) temperature no longer exceeds the programmed THIGH limit and (2) upon reading the Control/Status Register. If the temperature no longer exceeds the THIGH limit, the status Bit remains set until it is read by the master so that the system can check the history of what caused the OVERTEMP to assert. Bit : Temperature Low (TLOW) Flag Bit. This Bit is set to "1" when the measured temperature falls below the TLOW limit stored in the programmable TLOW register. The flag is reset to "0" when both of two conditions are met: (1) temperature is no longer below the programmed TLOW limit and (2) upon reading the Control/Status Register. If the temperature is no longer below, or equal to, the TLOW limit, the status Bit remains set until it is read by the master so that the system can check the history of what caused the OVERTEMP to assert. Bit : Data Available (DAV) Status Bit. This Bit is "0" when the temperature sensor is in the process of converting a new temperature. It is "1" when the conversion is done. It is reset after each read and goes high again after one temperature conversion is done. In one-shot mode: after initiating a temperature conversion while operating, this status Bit can be monitored to indicate when the conversion is done. After triggering the one-shot conversion, the data in the temperature register is invalid until this Bit is high (i.e., after completion of the first conversion). Bit : OVERTEMP Disable Bit. When set to "0" the OVERTEMP output is enabled. When set to "1" the OVERTEMP output is disabled. This Bit also controls the OVERTEMP Status Bit (this register, Bit ) since that Bit reflects the state of the OVERTEMP pin. Bit : OVERTEMP Polarity Bit. When set to "1", OVERTEMP is active-high. When "0" it is active-low. www.national.com 16 LM95172 Control/Status Register (Continued) Bit : Temperature Resolution Bits. Selects one of four user-programmable temperature data resolutions as indicated in the following table. Control/Status Register Bit 5 0 0 1 1 Bit : Always write a zero to this Bit. Bit : Reserved Bits. Will return whatever was last written to them. Value is zero on power-up. Bit : Always write a zero to this Bit. Reset State: 0000h Reset Conditions: Upon Power-on Reset. 1.7.4 THIGH: Upper Limit Register (Read/Write) Pointer Address: 82h (Read); 02h (Write) D15 Sign D7 1°C D14 128°C D6 0.5°C D13 64°C D5 0.25°C D12 32°C D4 D11 16°C D3 D10 8°C D2 Reserved D9 4°C D1 D8 2°C D0 Bit 4 0 1 0 1 Bits 13 14 15 16 Resolution °C 0.0625 0.03125 0.015625 0.0078125 Bit : Upper-Limit Temperature byte. If the measured temperature, stored in the temperature register, exceeds this userprogrammable temperature limit, the OVERTEMP pin will assert and the THIGH flag in the Control/Status register will be set to "1". Bit : Reserved. Returns all zeroes when read. Reset State: 4880h (+145°C) Reset Conditions: Upon Power-on Reset. 1.7.5 TLOW: Lower Limit Register (Read/Write) Pointer Address: 83h (Read); 03h (Write) D15 Sign D7 1°C D14 128°C D6 0.5°C D13 64°C D5 0.25°C D12 32°C D4 D11 16°C D3 D10 8°C D2 Reserved D9 4°C D1 D8 2°C D0 Bit : Lower-Limit Temperature byte. If the measured temperature that is stored in the temperature register falls below this user-programmable temperature limit, the OVERTEMP pin will not assert and the TLOW flag in the Control/Status register will be set to "1". Bit : Reserved. Returns all zeroes when read. Reset State: 4600h (+140°C) Reset Conditions: Upon Power-on Reset. 17 www.national.com LM95172 1.7.6 MFGID: Manufacturer, Product, and Step ID Register (Read Only) Pointer Address: 87h D15 1 D7 0 D14 0 D6 0 D13 0 D5 1 D12 0 D4 1 D11 0 D3 0 D10 0 D2 0 D9 0 D1 0 D8 0 D0 0 Bit : Manufacturer Identification Byte. Always returns 80h to uniquely identify the manufacturer as National Semiconductor Corporation. Bit : Product Identification Nibble. Always returns 30h to uniquely identify this part as the LM95172EWG. Bit : Die Revision Nibble. Returns 0h to uniquely identify the revision level as zero. Reset State: 8030h Reset Conditions: Upon Power-on Reset. www.national.com 18 LM95172 2.0 Typical Applications 30076620 FIGURE 13. Temperature monitor using Intel 196 processor 30076619 FIGURE 14. LM95172EWG digital input control using microcontroller's general purpose I/O. 19 www.national.com LM95172 Physical Dimensions inches (millimeters) unless otherwise noted 10-pin Cerpack Package LM95172EWG www.national.com 20 LM95172 Notes 21 www.national.com LM95172 13-Bit to 16-Bit 200°C Digital Temp Sensor with 3-Wire Interface Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Amplifiers Audio Clock and Timing Data Converters Interface LVDS Power Management Switching Regulators LDOs LED Lighting Voltage References PowerWise® Solutions Temperature Sensors PLL/VCO www.national.com/amplifiers www.national.com/audio www.national.com/timing www.national.com/adc www.national.com/interface www.national.com/lvds www.national.com/power www.national.com/switchers www.national.com/ldo www.national.com/led www.national.com/vref www.national.com/powerwise WEBENCH® Tools App Notes Reference Designs Samples Eval Boards Packaging Green Compliance Distributors Quality and Reliability Feedback/Support Design Made Easy Design Support www.national.com/webench www.national.com/appnotes www.national.com/refdesigns www.national.com/samples www.national.com/evalboards www.national.com/packaging www.national.com/quality/green www.national.com/contacts www.national.com/quality www.national.com/feedback www.national.com/easy www.national.com/solutions www.national.com/milaero www.national.com/solarmagic www.national.com/training Applications & Markets Mil/Aero PowerWise® Design University Serial Digital Interface (SDI) www.national.com/sdi www.national.com/wireless www.national.com/tempsensors SolarMagic™ THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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