View LM74AMDA_988532.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

LM74A SPI/MICROWIRE 12-Bit Plus Sign Temperature Sensor (LM74 in Die Form)
December 2001
LM74A SPI/MICROWIRETM 12-Bit Plus Sign Temperature Sensor (LM74 in Die Form)
General Description
The LM74A is a temperature sensor, Delta-Sigma analog-to-digital 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 A. 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 (0.0625C per LSB) while operating over a temperature range of -55C to +150C. The LM74A accuracy of 3.5C is specified over a temperature range of 0C to +150C. The LM74A's 4.5V to 5.5V 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. n Disk Drives n Office Electronics n Electronic Test Equipment
Features
n 0.0625C temperature resolution. n Shutdown mode conserves power between temperature reading n SPI and MICROWIRE Bus interface n LM74 is available in a 5-Bump micro SMD and 8-pin SOP
Key Specifications
j Supply Voltage j Supply Current
4.5V to 5.5V operating shutdown 310A (typ) 520A (max) 8A (typ)
j Temperature
0C to 140C 140C to 150C
Accuracy
3.0C(max) 3.5C(max)
Applications
n System Thermal Management n Personal Computers
Simplified Block Diagram
20017701
MICROWIRE (R) is a registered trademark of National Semiconductor Corporation.
(c) 2001 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 MDA NS Package Number No Package, Die Supply Voltage 4.5V to 5.5V Transport Media 7k unit surftape tape-and-reel
Pin Descriptions
Label SI/O SC GND NC CS V+ Back Pin # 1 2 3 4 5 6 (Backside) 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. Bypass with a 0.1 F ceramic capacitor. Can go to GND connection
www.national.com
2
LM74A
Typical Application
20017703
FIGURE 1. COP Microcontroller Interface
3
www.national.com
LM74A
Absolute Maximum Ratings
Supply Voltage Voltage at any Pin Input Current at any Pin (Note 2) Package Input Current (Note 2) Storage Temperature ESD Susceptibility (Note 4) Human Body Mode Machine Model
(Note 1)
Operating Ratings
Operating Temperature Range Specified Temperature Range (Note 5) LM74A Supply Voltage Range (+VS) 0C to +150C TMIN to TMAX 0C to +150C +4.5V to +5.5V
-0.3V to 6.0V -0.3V to V+ + 0.3V 5 mA 20 mA -65C to +150C 2000V 200V
Temperature-to-Digital Converter Characteristics
Unless otherwise noted, these specifications apply for V+ = 4.5V to 5.5V (Note 6). Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ =+25C, unless otherwise noted. Parameter Temperature Error (Note 6) Conditions TA = 0C to +140C TA = +140C to +150C Resolution Temperature Conversion Time Quiescent Current (Note 9) Serial Bus Inactive Serial Bus Active Shutdown Mode, V+ = 5V 13 280 310 310 8 425 520 Typical (Note 7) Limits (Note 8) Units (Limit) C (max) C (max) Bits ms (max) A (max) A A
3.0 3.5
Logic Electrical Characteristics
DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for V+ = 4.5V to 5.5V (Note 6). Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ =+25C, 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 A IOL = +2 mA VO = GND VO = V + V+ = 4.5V to 5.5V VIN = V
+
Conditions
Typical (Note 7)
Limits (Note 8) 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) A (max) A (min) pF V (min) V (max) A (min) A (max)
0.8 0.005 -0.005 20
0.33 3.0 -3.0 2.4 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 (Note 6); CL (load capacitance) on output lines = 100 pF unless otherwise specified. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = +25C, 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 7) Limits (Note 8) 0.16 DC 100 70 100 200 50 30 Units (Limit) s (min) (max) ns (min) ns (max) ns (max) ns (max) ns (min) ns (min)
20017704
FIGURE 2. Data Output Timing Diagram
20017705
FIGURE 3. TRI-STATE Data Output Timing Diagram
5
www.national.com
LM74A
20017706
FIGURE 4. Data Input Timing Diagram
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: See AN-450 "Surface Mounting Methods and Their Effect on Product Reliability" or the section titled "Surface Mount" found in a current National Semiconductor Linear Data Book for other methods of soldering surface mount devices. Note 4: Human body model, 100 pF discharged through a 1.5 k resistor. Machine model, 200 pF discharged directly into each pin. Note 5: The life expectancy of the LM74 will be reduced when operating at elevated temperatures. Note 6: All LM74 parts will function over the V+ supply voltage range of 3V to 5.5V. The LM74A temperature error specifications for temperature ranges of 0C to +140C, and 0C to +150C include error induced by power supply variation of 10% from the nominal value of 5V. Note 7: Typicals are at TA = 25C and represent most likely parametric norm. Note 8: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level). Note 9: 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 10: For best accuracy, minimize output loading. Higher sink currents can affect sensor accuracy with internal heating. This can cause an error of 0.64C at full rated sink current and saturation voltage based on junction-to-ambient thermal resistance.
Electrical Characteristics
20017708
FIGURE 5. Temperature-to-Digital Transfer Function (Non-linear scale for clarity)
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 ADC (Delta-Sigma 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 LM74 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 LM74 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 (R) . 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 LM74 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 LM74 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 LM74 out of shutdown. The following codes should only be transmitted to the LM74:
* 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 LM74 during production testing. Only eight bits have been defined above since only the last eight transmitted are detected by the LM74, 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 LM74 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 0.0625C: Temperature +150C +125C +25C +0.0625C 0C -0.0625C -25C -55C 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 LM74 as shown in Figure 7c. The serial bus is still active when the LM74 is in shutdown. Current draw drops to less than 10 A between serial communications. When in shutdown mode the LM74 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.
* * * * * *
00 hex 01 hex 03 hex 07 hex 0F hex 1F hex
www.national.com
8
LM74A
1.0 Functional Description
1.5 INTERNAL REGISTER STRUCTURE
(Continued)
The LM74 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 LM74 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 = 0.0625C. 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 LM74 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 LM74 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 LM74. Since the EEPROM is used for storing calibration coefficients, the LM74 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. LM74 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)
Physical Dimensions
unless otherwise noted
inches (millimeters)
20017727
Bond Pad Layout Order Number LM74A MDA Bare Die TOP VIEW 1.40mm x 1.57 mm (55 x 62 mils) For Bond Pad Mechanical Dimensions see Connection Diagram Section
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.
National Semiconductor Corporation Americas Email: support@nsc.com National Semiconductor Europe Fax: +49 (0) 180-530 85 86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Francais Tel: +33 (0) 1 41 91 8790
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.
National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: ap.support@nsc.com
National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507
www.national.com
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.

▲Up To Search▲

Price & Availability of LM74AMDA

	To Download LM74AMDA Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .