LM74A SPI/MICROWIRE™ 12-Bit Plus Sign Temperature Sensor (LM74 in Die Form) General Description Applications The LM74A is a temperature sensor, Delta-Sigma analog-todigital converter with an SPI and MICROWIRE compatible interface in die form. The host can query the LM74A at any time to read temperature. A shutdown mode decreases power consumption to less than 10 µA. This mode is useful in systems where low average power consumption is critical. n n n n n This particular data sheet applies to the LM74 in die form. The LM74 is available in the SO-8 package as well as an 5-Bump micro SMD package please refer to LM74 data sheet for detailed specifictions pertaining to the packaged parts. The LM74A has 12-bit plus sign temperature resolution (0.0625˚C per LSB) while operating over a temperature range of −40˚C to +150˚C. The LM74A-5 MDA accuracy of ± 3.5˚C is specified over a temperature range of 0˚C to +150˚C. Features The LM74A’s 4.5V to 5.5V or 3.0V to 3.6V supply voltage range, low supply current and simple SPI interface make it ideal for a wide range of applications. These include thermal management and protection applications in hard disk drives, printers, electronic test equipment, and office electronics. System Thermal Management Personal Computers Disk Drives Office Electronics Electronic Test Equipment n 0.0625˚C temperature resolution. n Shutdown mode conserves power between temperature reading n SPI and MICROWIRE Bus interface n LM74 is also available in a 5-Bump micro SMD and 8-pin MSOP Key Specifications j Supply Voltage LM74A-5 4.5V to 5.5V LM74A-3 j Supply Current 3.0V to 3.6V operating 310µA (typ) 520µA (max) shutdown 8µA (typ) 0˚C to 140˚C ± 3.0˚C(max) 140˚C to 150˚C ± 3.5˚C(max) j LM74A-5 MDA Temperature Accuracy Simplified Block Diagram 20017701 MICROWIRE™ is a trademark of National Semiconductor Corporation. TRI-STATE ® is a registered trademark of National Semiconductor Corporation. © 2004 National Semiconductor Corporation DS200177 www.national.com LM74A SPI/MICROWIRE 12-Bit Plus Sign Temperature Sensor (LM74 in Die Form) November 2004 LM74A Connection Diagram LM74A Bond Pad Layout 20017727 TOP VIEW 1.40mm x 1.57 mm (55 x 62 mils) Bond Pad Mechanical Dimensions Dimensions of bond pad coordinates are in millimeters. Origin of coordinates: center of die. X-Direction is in the longitudinal axis of the die. Coordinates refer to center of Bond Pad. Pin# X Y 1 -0.569 mm +0.585 mm 2 -0.537 mm +0.314 mm 3 -0.569 mm -0.554 mm 4 n/a n/a 5 +0.537 mm +0.277 mm 6 +0.569 mm +0.569 mm Back Ordering Information Order Number NS Package Number Supply Voltage Transport Media LM74A-5 MDA No Package, Die 4.5V to 5.5V 7k unit surftape tape-and-reel LM74A-3 MDA No Package, Die 3.0V to 3.6V 7k unit surftape tape-and-reel Pin Descriptions Label Pin # Function Typical Connection SI/O 1 Slave Input/Output - Serial bus bi-directional data line. Shmitt trigger input. From and to Controller SC 2 Slave Clock - Serial bus clock Shmitt trigger input line. From Controller Ground GND 3 Power Supply Ground NC 4 No Connection No Connection CS 5 Chip Select input. From Controller V+ 6 Positive Supply Voltage Input DC Voltage from 4.5V to 5.5V for the LM74A-5 and 3.0V to 3.6V for the LM74A-3. Bypass with a 0.1 µF ceramic capacitor. Back www.national.com (Backside) Can go to GND connection 2 LM74A Typical Application 20017703 FIGURE 1. COP Microcontroller Interface 3 www.national.com LM74A Absolute Maximum Ratings (Note 1) Supply Voltage Voltage at any Pin Operating Ratings −0.3V to 6.0V Operating Temperature Range −40˚C to +150˚C −0.3V to V+ + 0.3V Specified Temperature Range TMIN to TMAX Input Current at any Pin (Note 2) 5 mA Package Input Current (Note 2) (Note 4) LM74A 20 mA Storage Temperature Supply Voltage Range (+VS) −65˚C to +150˚C ESD Susceptibility (Note 3) Human Body Mode Machine Model -40˚C to +150˚C 2000V 200V LM74-5 MDA +4.5V to +5.5V LM74-3 MDA +3.0V to +3.6V Temperature-to-Digital Converter Characteristics Unless otherwise noted, these specifications apply for V+ = 4.5V to 5.5V for the LM74-5 MDA and V+ = 3.0V to 3.6V for the LM74-3 MDA.(Note 5). Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ=+25˚C, unless otherwise noted. Parameter Conditions Temperature Error (Note 5) Typical (Note 6) LM74-5 MDA Limits (Note 7) TA = 0˚C to +140˚C ± 3.0 TA = +140˚C to +150˚C ± 3.5 LM74-3 MDA Limits (Note 7) ˚C (max) ˚C (max) ±5 TA = -40˚C to +150˚C Resolution Units (Limit) ˚C (max) 13 Bits Temperature Conversion Time (Note 8) 280 425 ms (max) Quiescent Current Serial Bus Inactive 310 520 µA (max) Serial Bus Active 310 µA Shutdown Mode, V+ = 5V 8 µA Logic Electrical Characteristics DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for V+ = 4.5V to 5.5V for the LM74-5 MDA and V+ = 3.0V to 3.6V for the LM74-3 MDA.(Note 5). Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ=+25˚C, unless otherwise noted. Symbol VIN(1) Parameter Conditions Typical (Note 6) Logical “1” Input Voltage Limits (Note 7) Units (Limit) V+ x 0.7 V (min) + V + 0.3 VIN(0) Logical “0” Input Voltage Input Hysteresis Voltage V+ = 4.5V to 5.5V + IIN(1) Logical “1” Input Current VIN = V IIN(0) Logical “0” Input Current VIN = 0V CIN All Digital Inputs V (max) −0.3 V (min) V+ x 0.3 V (max) 0.33 V (min) 0.005 3.0 µA (max) −0.005 −3.0 µA (min) 0.8 20 pF + VOH High Level Output Voltage IOH = −400 µA V x 0.7 V (min) VOL Low Level Output Voltage IOL = +2 mA 0.4 V (max) IO_TRI-STATE TRI-STATE Output Leakage Current VO = GND V O = V+ −1 +1 µA (min) µA (max) www.national.com 4 Unless otherwise noted, these specifications apply for V+ = 4.5V to 5.5V for the LM74-5 MDA and V+ = 3.0V to 3.6V for the LM74-3 MDA.(Note 5). Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ=+25˚C, unless otherwise noted. Symbol Parameter Conditions Typical (Note 6) Limits (Note 7) Units (Limit) µs (min) (max) t1 SC (Clock) Period 0.16 DC t2 CS Low to SC (Clock) High Set-Up Time 100 ns (min) t3 CS Low to Data Out (SO) Delay 70 ns (max) t4 SC (Clock) Low to Data Out (SO) Delay 100 ns (max) t5 CS High to Data Out (SO) TRI-STATE 200 ns (max) t6 SC (Clock) High to Data In (SI) Hold Time 50 ns (min) t7 Data In (SI) Set-Up Time to SC (Clock) High 30 ns (min) Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating the device beyond its rated operating conditions. Note 2: When the input voltage (VI) at any pin exceeds the power supplies (VI < GND or VI > +VS) the current at that pin should be limited to 5 mA. The 20 mA maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5 mA to four. Note 3: Human body model, 100 pF discharged through a 1.5 kΩ resistor. Machine model, 200 pF discharged directly into each pin. Note 4: The life expectancy of the LM74A will be reduced when operating at elevated temperatures. Note 5: All LM74A parts will function over the V+ supply voltage range of 3V to 5.5V. The LM74A temperature error specifications for temperature ranges of 0˚C to +140˚C, 0˚C to +150˚C and −40˚C to +150˚C include error induced by power supply variation of ± 10% from the nominal value of 5V or 3.3V. Note 6: Typicals are at TA = 25˚C and represent most likely parametric norm. Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level). Note 8: This specification is provided only to indicate how often temperature data is updated. The LM74A 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. Note 9: For best accuracy, minimize output loading. Higher sink currents can affect sensor accuracy with internal heating. This can cause an error of 0.64˚C at full rated sink current and saturation voltage based on junction-to-ambient thermal resistance. Timing Diagrams 20017704 FIGURE 2. Data Output Timing Diagram 5 www.national.com LM74A Serial Bus Digital Switching Characteristics LM74A Timing Diagrams (Continued) 20017705 FIGURE 3. TRI-STATE Data Output Timing Diagram 20017706 FIGURE 4. Data Input Timing Diagram 20017708 Temperature-to-Digital Transfer Function (Non-linear scale for clarity) FIGURE 5. www.national.com 6 LM74A TRI-STATE Test Circuit 20017707 FIGURE 6. Typical Performance Characteristics Average Power-On Reset Voltage vs Temperature Static Supply Current vs Temperature 20017723 20017721 Temperature Error 20017726 7 www.national.com LM74A • 3F hex • 7F hex • FF hex any others may place the part into a Test Mode. Test Modes are used by National Semiconductor to thoroughly test the function of the LM74A during production testing. Only eight bits have been defined above since only the last eight transmitted are detected by the LM74A, before CS is taken HIGH. The following communication can be used to determine the Manufacturer’s/Device ID and then immediately place the part into continuous conversion mode. With CS continuously low: • Read 16 bits of temperature data • Write 16 bits of data commanding shutdown • Read 16 bits of Manufacture’s/Device ID data • Write 8 to 16 bits of data commanding Conversion Mode • Take CS HIGH. Note that 250 ms will have to pass for a conversion to complete before the LM74A actually transmits temperature data. 1.0 Functional Description The LM74A temperature sensor incorporates a band-gap type temperature sensor and 12-bit plus sign ∆Σ ADC (DeltaSigma Analog-to-Digital Converter). Compatibility of the LM74’s three wire serial interface with SPI and MICROWIRE allows simple communications with common microcontrollers and processors. Shutdown mode can be used to optimize current drain for different applications. A Manufacture’s/ Device ID register identifies the LM74A as National Semiconductor product. 1.1 POWER UP AND POWER DOWN The LM74A always powers up in a known state. The power up default condition is continuous conversion mode. Immediatly after power up the LM74A will output an erroneous code until the first temperature conversion has completed. When the supply voltage is less than about 1.6V (typical), the LM74A is considered powered down. As the supply voltage rises above the nominal 1.6V power up threshold, the internal registers are reset to the power up default state described above. 1.2 SERIAL BUS INTERFACE The LM74A operates as a slave and is compatible with SPI or MICROWIRE bus specifications. Data is clocked out on the falling edge of the serial clock (SC), while data is clocked in on the rising edge of SC. A complete transmit/receive communication will consist of 32 serial clocks. The first 16 clocks comprise the transmit phase of communication, while the second 16 clocks are the receive phase. When CS is high SI/O will be in TRI-STATE ® . Communication should be initiated by taking chip select (CS) low. This should not be done when SC is changing from a low to high state. Once CS is low the serial I/O pin (SI/O) will transmit the first bit of data. The master can then read this bit with the rising edge of SC. The remainder of the data will be clocked out by the falling edge of SC. Once the 14 bits of data (one sign bit, twelve temperature bits and 1 high bit) are transmitted the SI/O line will go into TRI-STATE. CS can be taken high at any time during the transmit phase. If CS is brought low in the middle of a conversion the LM74A will complete the conversion and the output shift register will be updated after CS is brought back high. The receive phase of a communication starts after 16 SC periods. CS can remain low for 32 SC cycles. The LM74A will read the data available on the SI/O line on the rising edge of the serial clock. Input data is to an 8-bit shift register. The part will detect the last eight bits shifted into the register. The receive phase can last up to 16 SC periods. All ones must be shifted in order to place the part into shutdown. A zero in any location will take the LM74A out of shutdown. The following codes should only be transmitted to the LM74A: • 00 hex • 01 hex • • • • 1.3 TEMPERATURE DATA FORMAT Temperature data is represented by a 13-bit, two’s complement word with an LSB (Least Significant Bit) equal to 0.0625˚C: Temperature Hex +150˚C 0100 1011 0000 0111 4B 07h +125˚C 0011 1110 1000 0111 3E 87h +25˚C 0000 1100 1000 0111 0B 87h +0.0625˚C 0000 0000 0000 1111 00 0Fh 0˚C 0000 0000 0000 0111 00 07h −0.0625˚C 1111 1111 1111 1111 FF FFh −25˚C 1111 0011 1000 0111 F3 87h −55˚C 1110 0100 1000 0111 E4 87h Note: The last two bits are TRI-STATE and depicted as one in the table. 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. 1.4 SHUTDOWN MODE/MANUFACTURER’S ID Shutdown mode is enabled by writing XX FF to the LM74A as shown in Figure 7c. The serial bus is still active when the LM74A is in shutdown. Current draw drops to less than 10 µA between serial communications. When in shutdown mode the LM74A always will output 1000 0000 0000 0XX. This is the manufacturer’s/Device ID information. The first 5-bits of the field (1000 0XXX) are reserved for manufacturer’s ID. 03 hex 07 hex 0F hex 1F hex www.national.com Digital Output Binary 8 LM74A 1.0 Functional Description (Continued) 1.5 INTERNAL REGISTER STRUCTURE The LM74A has three registers, the temperature register, the configuration register and the manufacturer’s/device identification register. The temperature and manufacturer’s/device identification registers are read only. The configuration register is write only. 1.5.1 Configuration Register (Selects shutdown or continuous conversion modes): (Write Only): D15 D14 D13 D12 D11 D10 D9 D8 X X X X X X X X D7 D6 D5 D4 D3 D2 D1 D0 Shutdown D0–D15 set to XX FF hex enables shutdown mode. D0–D15 set to 00 00 hex sets Continuous conversion mode. Note: setting D0-D15 to any other values may place the LM70 into a manufacturer’s test mode, upon which the LM74A will stop responding as described. These test modes are to be used for National Semiconductor production testing only. See Section 1.2 Serial Bus Interface for a complete discussion. 1.5.2 Temperature Register (Read Only): D15 MSB D14 D13 Bit 11 Bit 10 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB 1 X X D0–D1: Undefined. TRI-STATE will be output on SI/0. D2: Always set high. D3–D15: Temperature Data. One LSB = 0.0625˚C. Two’s complement format. 1.5.3 Manufacturer’s/Device Id Register (Read Only): D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 X X D0–D1: Undefined. TRI-STATE will be output on SI/0. D2–D15: Manufacturer’s/Device ID Data. This register is accessed whenever the LM74A is in shutdown mode. 9 www.national.com LM74A 2.0 Serial Bus Timing Diagrams 20017714 a) Reading Continuous Conversion - Single Eight-Bit Frame 20017715 b) Reading Continuous Conversion - Two Eight-Bit Frames 20017718 c) Writing Shutdown Control FIGURE 7. Timing Diagrams www.national.com 10 3.1 LIGHT SENSITIVITY a wavelength of 254nm, for greater than 20 minutes will deprogram the EEPROM cells in the LM74A. Since the EEPROM is used for storing calibration coefficients, the LM74A will function but the temperature accuracy will no longer be as specified. Light can penetrate through the side of the die as well. The LM74A in die form should not be exposed to ultraviolet light. Exposing the LM74A to bright sunlight will not immediatly cause a change in the output reading. Our experiments show that directly exposing the circuit side (pad side) of the die to high intensity (≥ 1mW/cm2) ultraviolet light, centered at 4.0 Typical Applications 20017720 FIGURE 8. Temperature monitor using Intel 196 processor 20017719 FIGURE 9. LM74A digital input control using micro-controller’s general purpose I/O. 11 www.national.com LM74A 3.0 Application Hints LM74A SPI/MICROWIRE 12-Bit Plus Sign Temperature Sensor (LM74 in Die Form) 5.0 Revision History Date Revision 10/12/2004 1. Added LM74A-3 MDA specifications. 2. Updated order number of LM74A MDA to LM74A-5 MDA. 07/17/2001 Released to web originaly. Bond Pad Layout 20017727 Bond Pad Layout Order Number LM74A-5 MDA or LM74A-3 MDA Bare Die TOP VIEW 1.40mm x 1.57 mm (55 x 62 mils) For Bond Pad Mechanical Dimensions see Connection Diagram Section National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. For the most current product information visit us at www.national.com. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. BANNED SUBSTANCE COMPLIANCE National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. 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