LM95172 13-Bit to 16-Bit 200°C Digital Temp Sensor with 3-Wire Interface General Description Features 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. ■ LM95172EWG is AEC-Q100 Grade 0 qualified and is 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. 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 Automotive high temperature applications Industrial Power Controllers Industrial motors, gear boxes Geothermal instrumentation High Temperature Test Equipment 400 µA (typ) Shutdown −40°C to +140°C 4 µA (max) Shutdown −40°C to +175°C 12 µA (max) Shutdown −40°C to +200°C 28 µA (max) ■ 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 Applications ■ ■ ■ ■ ■ 3.0V to 5.5V ±3.0°C (max) ±1.0°C (max) ±2.0°C (max) ±2.0°C (max) ±3.5°C (max) ■ 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 13-Bit to 16-Bit 200°C Digital Temp Sensor with 3-Wire Interface December 16, 2009 LM95172 Pin Descriptions Pin Number Name Type 1 OVERTEMP Output 2 SC 3 NC 4 Description Typical Connection OVERTEMP Alarm Over-temperature Alarm Output, Open-drain. Active Low on POR. Requires a pull-up resistor to VDD IO. Input Serial Clock input Serial clock from the Controller N/A No Connect Do not connect to this pin. CS Input Chip Select input Chip Select input for the bus. Low pass filtered. 5 GND Ground Power Supply Ground Ground 6 NC N/A No Connect Do not connect to this pin. 7 SI/O 8 NC Bidirectio Serial I/O nal N/A Serial I/O Data line to or from the Controller No Connect 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. 9 VDD ANALOG Power Analog Power Supply Voltage 10 VDD IO Power Digital Power Supply Voltage Simplified Block Diagram 30076601 Ordering Information www.national.com Order Number NS Package Number Transport Media LM95172EWG WG10A 54 units in tray 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 Operating Ratings Specified Temperature Range Analog Supply Voltage Range VDD ANALOG Digital Supply Voltage Range VDD IO −0.2V to 6.0V −0.2V to (VDD IO + 0.2V) 5 mA −65°C to +175°C −40°C to +200°C +3.0V to +5.5V +3.0V to +5.5V Package Thermal Resistances Package θJA 10-Lead CERPACK 175°C/W 235°C 2500 V 250 V 1000 V 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 Temperature Accuracy (Note 8) Typical (Note 3) Conditions TA = +175°C to +200°C ±3.0 TA = +130°C to +160°C ±1.0 TA = +120°C to +130°C ±2.0 TA = +160°C to +175°C ±2.0 TA = −40°C to +120°C Res 1 Bit Units (Limit) °C (max) ±3.5 Res 0 Bit 13 0.0625 Bits °C 0 0 0 1 14 0.03125 Bits °C 1 0 15 0.015625 Bits °C 1 1 16 0.0078125 Bits °C Resolution For 13 Bits Resolution 43 For 14 Bits Resolution 87 Temperature Conversion Time For 15 Bits Resolution 175 For 16 BIts Resolution Bus Inactive Continuous Conversion Mode Shutdown Mode 400 TA = −40°C to 175°C TA = −40°C to 200°C Total Quiescent Current (Note 9) ms (max) 350 TA = −40°C to 140°C 456 510 500 650 TA = −40°C to 140°C 4 TA = −40°C to 175°C 12 TA = −40°C to 200°C www.national.com LM95172EWG Limits (Note 2) 4 28 75 μA (max) Typical (Note 3) Conditions TA = −40°C to 140°C Power-On Reset TA = −40°C to 175°C Threshold TA = −40°C to 200°C 5 LM95172EWG Limits (Note 2) Units (Limit) 0.9 V (min) 2.1 V (max) 0.8 V (min) 2.1 V (max) 0.3 V (min) 2.1 V (max) www.national.com LM95172 Parameter 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 Parameter VIH Logical "1" Input Voltage VIL Logical "0" Input Voltage Conditions VHYST Digital Input Hysteresis IIH Logical “1” Input Leakage Current IIL Logical “0” Input Current VOH Output High Voltage VOL Output Low Voltage OVERTEMP Output Saturation Voltage www.national.com Typical (Note 3) Limits (Note 2) Units (Limit) 0.75×VDD IO V (min) 0.25×VDD IO V (max) VDD IO = 3.0V 0.63 0.42 V (min) VDD IO = 3.3V 0.79 0.56 VDD IO = 3.6V 0.97 0.72 VDD IO = 4.5V 0.9 VDD IO = 5.0V 1.0 VDD IO = 5.5V 1.1 VIN = VDD IO 1 μA (max) VIN = 0V −1 μA (max) IOH = 100 μA (Source) VDD IO − 0.2 V (min) IOH = 2 mA (Source) VDD IO − 0.45 IOL = 100 μA (Sink) 0.2 IOL = 2 mA (Sink) 0.45 IOL = 2 mA (Sink) 0.45 6 V (max) V(max) 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 Typical (Note 3) Parameter Limits (Note 2) Units (Limit) t1 SC (Serial Clock) Period 765 ns (min) t2 CS (Chip Select) Low to SC High Set-Up Time (Note 5) 1.25 µs (min) t3 CS Low to SI/O Output Delay (Note 5) 1 µs (max) t4 SC Low to SI/O Output Delay 120 ns (max) t5 CS High to Data Out (SI/O) TRI-STATE 220 ns (max) t6 SC High to SI/O Input Hold Time 50 ns (min) t7 SI/O Input to SC High Set-Up Time 30 ns (min) t8 SC Low to CS High Hold Time 50 ns (min) tTA Data Turn-Around Time: SI/O input (write to LM95172EWG) to output (read from LM95172EWG) 130 ns (max) tBUF Bus free time between communications: CS High to CS Low. (Note 5) 5 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. 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. 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- 30076622 FIGURE 8. LM95172EWG Functional Block Diagram 9 www.national.com LM95172 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 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. 1.1.3 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. 1.1.2 Power-Up Sequence Warning: In all cases listed below the VDD ANALOGwaveform must not lag the VDD IOwaveform 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 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 (-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. 1.2 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 LM95172 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. 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 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 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 +175°C +150°C +80°C +25°C +0.0625°C 0°C −0.0625°C −40°C 16-bit Binary All 16 Bits Bits D15 - D3 Hex Hex 0101011110000 000 5780 0101011110000 001 5781 0100101100000 000 4B00 0100101100000 001 4B01 0010100000000 000 2800 0010100000000 001 2801 0000110010000 000 0C80 0000110010000 001 0C81 0000000000001 000 0008 0000000000001 001 0009 0000000000000 000 0000 0000000000000 001 0001 1111111111111 000 FFF8 1111111111111 001 FFF9 1110110000000 000 EC00 1110110000000 001 EC01 0AF0 0960 0500 0190 0001 0000 1FFF 1D80 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 +175°C +150°C +80°C +25°C +0.03125°C 0°C −0.03125°C −40°C 16-bit Binary All 16 Bits Bits D15 - D2 Hex Hex 01010111100000 00 5780 01010111100000 01 5781 01001011000000 00 4B00 01001011000000 01 4B01 00101000000000 00 2800 00101000000000 01 2801 00001100100000 00 0C80 00001100100000 01 0C81 00000000000001 00 0004 00000000000001 01 0005 00000000000000 00 0000 00000000000000 01 0001 11111111111111 00 FFFC 11111111111111 01 FFFD 11101100000000 00 EC00 11101100000000 01 EC01 13 15E0 12C0 0A00 0320 0001 0000 3FFF 3B00 www.national.com LM95172 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. 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 LM95172 15-Bit Resolution. First bit (D15) is Sign and the last bit (D0) is Toggle. 15-bit Resolution Digital Output Temperature +175°C +150°C +80°C +25°C +0.015625°C 0°C −0.015625°C −40°C 16-bit Binary All 16 Bits Bits D15 - D1 Hex Hex 010101111000000 0 5780 010101111000000 1 5781 010010110000000 0 4B00 010010110000000 1 4B01 001010000000000 0 2800 001010000000000 1 2801 000011001000000 0 0C80 000011001000000 1 0C81 000000000000001 0 0002 000000000000001 1 0003 000000000000000 0 0000 000000000000000 1 0001 111111111111111 0 FFFE 111111111111111 1 FFFF 111011000000000 0 EC00 111011000000000 1 EC01 2BC0 2580 1400 0640 0001 0000 7FFF 7600 16-Bit Resolution. First bit (D15) is Sign and the last bit (D0) is the LSB. 16-bit Resolution Digital Output Temperature 16-bit Binary Hex +175°C 0101 0111 1000 0000 5780 +150°C 0100 1011 0000 0000 4B00 +80°C 0010 1000 0000 0000 2800 +25°C 0000 1100 1000 0000 0C80 +0.0078125°C 0000 0000 0000 0001 0001 0°C 0000 0000 0000 0000 0000 −0.0078125°C 1111 1111 1111 1111 FFFF −40°C 1110 1100 0000 0000 EC00 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. 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- www.national.com All 16 Bits 14 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 P6 P5 P4 P3 R/W 0 0 0 0 P2 P1 P0 Register Select Bit <7> 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 <6:3> Not Used. These Bits must be zero. If an illegal address is written, the LM95172EWG will return 0000h on the subsequent read. Bits <2:0> Pointer Address Bits. Points to desired register. See table below. P2 P1 P0 Register 0 0 0 Invalid. (Note 6) 0 0 1 Control/Status 0 1 0 THIGH 0 1 1 TLOW 1 0 0 1 0 1 1 1 0 1 1 1 Invalid. (Note 6) Identification Power-On Reset state: 00h Reset Conditions: Upon Power-on Reset 1.7.2 Temperature Register (Read Only): Default Register D7 1°C D6 0.5°C D15 D14 D13 D12 D11 D10 D9 D8 Sign 128°C 64°C 32°C 16°C 8°C 4°C 2°C D5 0.25°C D4 0.125°C D3 0.0625°C D2 0.03125°C D1 D0 0.015625°C Conversion - Toggle/ 0.0078125°C Bit <15:1>: 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 <1> is not used and, therefore, it is invalid and is always zero. Bit <0>: 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 1.7 INTERNAL REGISTER STRUCTURE 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 D13 D12 D11 D10 D9 D8 One-Shot OVERTEMP Reset Conversion Toggle OVERTEMP Status THIGH TLOW DAV D7 D6 D5 D4 D3 D2 D1 D0 OVERTEMP Disable OVERTEMP POL RES1 RES0 0 reserved reserved 0 Bit <15>: 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 <14>: One-Shot Bit. When in shutdown mode (Bit <15> 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 <15> is "0"). Always returns a "0" when read. Bit <13>: 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 <12>: 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 <11>: 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 <13>) 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 <10>: 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 <9>: 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 <8>: 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 <7>: 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 <11>) since that Bit reflects the state of the OVERTEMP pin. Bit <6>: OVERTEMP Polarity Bit. When set to "1", OVERTEMP is active-high. When "0" it is active-low. www.national.com 16 Bit <5:4>: Temperature Resolution Bits. Selects one of four user-programmable temperature data resolutions as indicated in the following table. Control/Status Register Resolution Bit 5 Bit 4 Bits °C 0 0 13 0.0625 0 1 14 0.03125 1 0 15 0.015625 1 1 16 0.0078125 Bit <3>: Always write a zero to this Bit. Bit <2:1>: Reserved Bits. Will return whatever was last written to them. Value is zero on power-up. Bit <0>: 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 D14 D13 D12 D11 D10 D9 D8 Sign 128°C 64°C 32°C 16°C 8°C 4°C 2°C D4 D3 D2 D1 D0 D7 D6 D5 1°C 0.5°C 0.25°C Reserved Bit <15:5>: 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 <4:0>: 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 D14 D13 D12 D11 D10 D9 D8 Sign 128°C 64°C 32°C 16°C 8°C 4°C 2°C D7 D6 D5 D4 D3 D2 D1 D0 1°C 0.5°C 0.25°C Reserved Bit <15:5>: 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 <4:0>: Reserved. Returns all zeroes when read. Reset State: 4600h (+140°C) Reset Conditions: Upon Power-on Reset. 17 www.national.com LM95172 Control/Status Register (Continued) LM95172 1.7.6 MFGID: Manufacturer, Product, and Step ID Register (Read Only) Pointer Address: 87h D15 D14 D13 D12 D11 D10 D9 D8 1 0 0 0 0 0 0 0 D7 D6 D5 D4 D3 D2 D1 D0 0 0 1 1 0 0 0 0 Bit <15:8>: Manufacturer Identification Byte. Always returns 80h to uniquely identify the manufacturer as National Semiconductor Corporation. Bit <7:4>: Product Identification Nibble. Always returns 30h to uniquely identify this part as the LM95172EWG. Bit <3:0>: 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 Design Support Amplifiers www.national.com/amplifiers WEBENCH® Tools www.national.com/webench Audio www.national.com/audio App Notes www.national.com/appnotes Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns Data Converters www.national.com/adc Samples www.national.com/samples Interface www.national.com/interface Eval Boards www.national.com/evalboards LVDS www.national.com/lvds Packaging www.national.com/packaging Power Management www.national.com/power Green Compliance www.national.com/quality/green Switching Regulators www.national.com/switchers Distributors www.national.com/contacts LDOs www.national.com/ldo Quality and Reliability www.national.com/quality LED Lighting www.national.com/led Feedback/Support www.national.com/feedback Voltage References www.national.com/vref Design Made Easy www.national.com/easy www.national.com/powerwise Applications & Markets www.national.com/solutions Mil/Aero www.national.com/milaero PowerWise® Solutions Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors SolarMagic™ www.national.com/solarmagic PLL/VCO www.national.com/wireless www.national.com/training PowerWise® Design University THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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