LM74A-3MDA

LM74A SPI/MICROWIRE 12-Bit Plus Sign Temperature Sensor (LM74 in Die Form) November 2004 LM74A SPI/MICROWIRE™ 12-Bit Plus Sign Temperature Sensor (LM74 in Die Form) General Description 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. 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. 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. Applications n n n n n System Thermal Management Personal Computers Disk Drives Office Electronics Electronic Test Equipment Features 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 j Supply Current LM74A-5 LM74A-3 operating shutdown 4.5V to 5.5V 3.0V to 3.6V 310µA (typ) 520µA (max) 8µA (typ) j LM74A-5 MDA 0˚C to 140˚C 140˚C to 150˚C ± 3.0˚C(max) ± 3.5˚C(max) 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 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# 1 2 3 4 5 6 Back X -0.569 mm -0.537 mm -0.569 mm n/a +0.537 mm +0.569 mm Y +0.585 mm +0.314 mm -0.554 mm n/a +0.277 mm +0.569 mm Ordering Information Order Number LM74A-5 MDA LM74A-3 MDA NS Package Number No Package, Die No Package, Die Supply Voltage 4.5V to 5.5V 3.0V to 3.6V Transport Media 7k unit surftape tape-and-reel 7k unit surftape tape-and-reel Pin Descriptions Label SI/O SC GND NC CS V+ Pin # 1 2 3 4 5 6 Function Slave Input/Output - Serial bus bi-directional data line. Shmitt trigger input. Slave Clock - Serial bus clock Shmitt trigger input line. Power Supply Ground No Connection Chip Select input. Positive Supply Voltage Input Typical Connection From and to Controller From Controller Ground No Connection From Controller 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. Can go to GND connection Back (Backside) www.national.com 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 Input Current at any Pin (Note 2) Package Input Current (Note 2) Storage Temperature ESD Susceptibility (Note 3) Human Body Mode Machine Model −0.3V to 6.0V −0.3V to V+ + 0.3V 5 mA 20 mA −65˚C to +150˚C 2000V 200V Operating Ratings Operating Temperature Range Specified Temperature Range (Note 4) LM74A Supply Voltage Range (+VS) LM74-5 MDA LM74-3 MDA +4.5V to +5.5V +3.0V to +3.6V −40˚C to +150˚C TMIN to TMAX -40˚C to +150˚C 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 Temperature Error (Note 5) Conditions TA = 0˚C to +140˚C TA = +140˚C to +150˚C TA = -40˚C to +150˚C Resolution Temperature Conversion Time Quiescent Current (Note 8) Serial Bus Inactive Serial Bus Active Shutdown Mode, V+ = 5V 13 280 310 310 8 425 520 Typical (Note 6) LM74-5 MDA Limits (Note 7) LM74-3 MDA Limits (Note 7) Units (Limit) ± 3.0 ± 3.5 ±5 ˚C (max) ˚C (max) ˚C (max) Bits ms (max) µA (max) µA 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) VIN(0) Parameter Logical “1” Input Voltage Logical “0” Input Voltage Input Hysteresis Voltage IIN(1) IIN(0) CIN VOH VOL IO_TRI-STATE Logical “1” Input Current Logical “0” Input Current All Digital Inputs High Level Output Voltage Low Level Output Voltage TRI-STATE Output Leakage Current IOH = −400 µA IOL = +2 mA VO = GND V O = V+ V+ = 4.5V to 5.5V VIN = V + Conditions Typical (Note 6) Limits (Note 7) V+ x 0.7 V + 0.3 −0.3 V+ x 0.3 + Units (Limit) V (min) V (max) V (min) V (max) V (min) µA (max) µA (min) pF V (min) V (max) µA (min) µA (max) 0.8 0.005 −0.005 20 0.33 3.0 −3.0 V x 0.7 0.4 −1 +1 + VIN = 0V www.national.com 4 LM74A Serial Bus Digital Switching 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 t1 t2 t3 t4 t5 t6 t7 SC (Clock) Period CS Low to SC (Clock) High Set-Up Time CS Low to Data Out (SO) Delay SC (Clock) Low to Data Out (SO) Delay CS High to Data Out (SO) TRI-STATE SC (Clock) High to Data In (SI) Hold Time Data In (SI) Set-Up Time to SC (Clock) High Parameter Conditions Typical (Note 6) Limits (Note 7) 0.16 DC 100 70 100 200 50 30 Units (Limit) µs (min) (max) ns (min) ns (max) ns (max) ns (max) ns (min) 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 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 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 • 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. 1.3 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 +150˚C +125˚C +25˚C +0.0625˚C 0˚C −0.0625˚C −25˚C −55˚C Digital Output Binary 0100 1011 0000 0111 0011 1110 1000 0111 0000 1100 1000 0111 0000 0000 0000 1111 0000 0000 0000 0111 1111 1111 1111 1111 1111 0011 1000 0111 1110 0100 1000 0111 Hex 4B 07h 3E 87h 0B 87h 00 0Fh 00 07h FF FFh F3 87h 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 8 LM74A 1.0 Functional Description 1.5 INTERNAL REGISTER STRUCTURE (Continued) 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 X D14 X D13 X D12 X D11 X D10 X D9 X D8 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 D12 Bit 9 D11 Bit 8 D10 Bit 7 D9 Bit 6 D8 Bit 5 D7 Bit 4 D6 Bit 3 D5 Bit 2 D4 Bit 1 D3 LSB D2 1 D1 X D0 X Bit 11 Bit 10 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 1 D14 0 D13 0 D12 0 D11 0 D10 0 D9 0 D8 0 D7 0 D6 0 D5 0 D4 0 D3 0 D2 0 D1 X D0 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 LM74A 3.0 Application Hints 3.1 LIGHT SENSITIVITY 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 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. 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 SPI/MICROWIRE 12-Bit Plus Sign Temperature Sensor (LM74 in Die Form) 5.0 Revision History Date 10/12/2004 07/17/2001 Revision 1. Added LM74A-3 MDA specifications. 2. Updated order number of LM74A MDA to LM74A-5 MDA. 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. 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