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LM75AIMM/NOPB

LM75AIMM/NOPB

  • 厂商:

    BURR-BROWN(德州仪器)

  • 封装:

    VSSOP-8_3X3MM

  • 描述:

    SENSOR TEMPERATURE I2C 8VSSOP

  • 数据手册
  • 价格&库存
LM75AIMM/NOPB 数据手册
Product Folder Sample & Buy Support & Community Tools & Software Technical Documents LM75A SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 LM75A Digital Temperature Sensor and Thermal Watchdog With Two-Wire Interface 1 Features 3 Description • • • The LM75A is an industry-standard digital temperature sensor with an integrated sigma-delta analog-to-digital converter (ADC) and I2C interface. The LM75A provides 9-bit digital temperature readings with an accuracy of ±2°C from –25°C to 100°C and ±3°C over –55°C to 125°C. 1 • • No External Components Required Shutdown Mode to Minimize Power Consumption Up to Eight LM75As can be Connected to a Single Bus Power up Defaults Permit Stand-Alone Operation as Thermostat Key Specifications: – Supply Voltage – LM75A: 2.7 V to 5.5 V – Supply Current – Operating: 280 μA (Typical) – Shutdown: 4 μA (Typical) – Temperature Accuracy – 25°C to 100°C: ±2°C (Max) – 55°C to 125°C: ±3°C (Max) The LM75A operates with a single supply from 2.7 V to 5.5 V. Communication is accomplished over a 2-wire interface which operates up to 400 kHz. The LM75A has three address pins, allowing up to eight LM75A devices to operate on the same 2-wire bus. The LM75A has a dedicated overtemperature output (O.S.) with programmable limit and hysteresis. This output has programmable fault tolerance, which lets the user to define the number of consecutive error conditions that must occur before O.S. is activated. The wide temperature and supply range and I2C interface make the LM75A ideal for a number of applications including base stations, electronic test equipment, office electronics, personal computers, and any other system in which thermal management is critical to performance. The LM75A is available in an SOIC-8 package and an VSSOP-8 package. 2 Applications • • • • General System Thermal Management Communications Infrastructure Electronic Test Equipment Environmental Monitoring Device Information(1) PART NUMBER LM75A PACKAGE BODY SIZE (NOM) SOIC (8) 4.90 mm × 3.91 mm VSSOP (8) 3.00 mm × 3.00 mm (1) For all available packages, see the orderable addendum at the end of the datasheet. Typical Application +VS 100 nF (typ) unless mounted close to processor 8 A0 Address A1 (Set as desired) A2 Interface SDA SCL 7 6 5 LM75 3 O.S. To Processor Interrupt Line 1 O.S. set to active low IRUZLUH25¶GPXOWLSOH interrupt line 2 4 GND 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. LM75A SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 www.ti.com Table of Contents 1 2 3 4 5 6 7 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Pin Configuration and Functions ......................... Specifications......................................................... 1 1 1 2 3 3 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 3 3 4 4 4 5 5 9 Absolute Maximum Ratings ...................................... ESD Ratings.............................................................. Recommended Operating Conditions....................... Thermal Information .................................................. Temperature-to-Digital Converter Characteristics..... Digital DC Characteristics ......................................... I2C Digital Switching Characteristics......................... Typical Characteristics .............................................. Detailed Description ............................................ 10 7.1 Overview ................................................................. 10 7.2 Functional Block Diagram ....................................... 10 7.3 7.4 7.5 7.6 8 Feature Description................................................. Device Functional Modes........................................ Programming........................................................... Register Maps ......................................................... 10 10 11 13 Application and Implementation ........................ 15 8.1 Application Information............................................ 15 8.2 Typical Applications ................................................ 15 8.3 System Examples ................................................... 16 9 Power Supply Recommendations...................... 18 10 Layout................................................................... 18 10.1 Layout Guidelines ................................................. 18 10.2 Layout Example .................................................... 19 11 Device and Documentation Support ................. 20 11.1 Trademarks ........................................................... 20 11.2 Electrostatic Discharge Caution ............................ 20 11.3 Glossary ................................................................ 20 12 Mechanical, Packaging, and Orderable Information ........................................................... 20 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision O (May 2013) to Revision P • Added Pin Configuration and Functions section, ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section .............................. 1 Changes from Revision N (May 2013) to Revision O • 2 Page Page Changed layout of National Data Sheet to TI format ........................................................................................................... 16 Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A LM75A www.ti.com SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 5 Pin Configuration and Functions 8-Pins SOIC (D) and VSSOP (DGK) Packages Top View Pin Functions PIN NO. NAME 1 SDA 2 DESCRIPTION TYPICAL CONNECTION I2C Serial Bi-Directional Data Line, Open Drain 2 From Controller, tied to a pullup resistor or current source SCL I C Clock Input From Controller, tied to a pullup resistor or current source 3 O.S. Overtemperature Shutdown, Open Drain Output Pull–up Resistor, Controller Interrupt Line 4 GND Power Supply Ground Ground 5 A2 6 A1 User-Set I2C Address Inputs Ground (Low, “0”) or +VS (High, “1”) 7 A0 8 +VS Positive Supply Voltage Input DC Voltage from 2.7 V to 5.5 V 100-nF bypass capacitor with 10-µF bulk capacitance in the near vicinity 6 Specifications 6.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) MIN MAX UNIT Supply Voltage Pin (+VS) −0.3 6.5 V Voltage at A0, A1and A2 Pins −0.3 (+VS + 0.3) and must be ≤ 6.5 V Voltage at OS, SCL and SDA Pins −0.3 6.5 V Input Current at any Pin (2) 5 mA Package Input Current (2) 20 mA O.S. Output Sink Current 10 mA O.S. Output Voltage 6.5 V 150 °C Storage temperature, Tstg (1) (2) –65 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. 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 5mA. The 20mA maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5mA to four. 6.2 ESD Ratings VALUE Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 V(ESD) (1) (2) Electrostatic discharge (1) UNIT ±2500 Charged-device model (CDM), per JEDEC specification JESD22C101 (2) ±1000 Machine model ±250 V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A 3 LM75A SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 www.ti.com 6.3 Recommended Operating Conditions (1) (2) Specified Temperature Range (TMIN to TMAX) Supply Voltage Range (+VS) LM75A (1) (2) MIN MAX UNIT −55 125 °C 2.7 5.5 V LM75A θJA (thermal resistance, junction-to-ambient) when attached to a printed circuit board with 2 oz. foil similar to the one shown in Thermal Information is summarized in the table below the Operating Ratings table. Reflow temperature profiles are different for lead-free and non-lead-free packages. Soldering process must comply with Reflow Temperature Profile specifications. Refer to www.ti.com/packaging.(2) 6.4 Thermal Information LM75A THERMAL METRIC (1) RθJA (1) Junction-to-ambient thermal resistance D DGK 8 PINS 8 PINS 200 250 UNIT °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. 6.5 Temperature-to-Digital Converter Characteristics Unless otherwise noted, these specifications apply for: +VS = 2.7 to 5.5 Vdc for LM75AIM. TA = TJ = 25°C, unless otherwise noted. PARAMETER TEST CONDITIONS Accuracy MIN TYP (1) TA = −25°C to +100°C –55°C ≤ TJ ≤ 125°C –2 2 TA = −55°C to +125°C –55°C ≤ TJ ≤ 125°C –3 3 Resolution 9 See (3) Temperature Conversion Time 300 I2C Inactive LM75A 0.28 I2C Inactive, –55°C ≤ TJ ≤ 125°C 0.5 Shutdown Mode, +VS = 3 V 4 Shutdown Mode, +VS = 5 V 6 UNIT °C Bits 100 See (3), –55°C ≤ TJ ≤ 125°C Quiescent Current MAX (2) ms mA μA μA O.S. Output Saturation Voltage IOUT = 4 mA, –55°C ≤ TJ ≤ 125°C O.S. Delay See (4), –55°C ≤ TJ ≤ 125°C TOS Default Temperature See (5) 80 °C THYST Default Temperature See (5) 75 °C (1) (2) (3) (4) (5) 4 0.8 1 6 V Conversion Typicals are at TA = 25°C and represent most likely parametric norm. Maximum values (limits) are ensured to AOQL (Average Outgoing Quality Level). The conversion-time specification is provided to indicate how often the temperature data is updated. The LM75A can be accessed at any time and reading the Temperature Register will yield result from the last temperature conversion. When the LM75A is accessed, the conversion that is in process will be interrupted and it will be restarted after the end of the communication. Accessing the LM75A continuously without waiting at least one conversion time between communications will prevent the device from updating the Temperature Register with a new temperature conversion result. Consequently, the LM75A should not be accessed continuously with a wait time of less than 300ms. O.S. Delay is user programmable up to 6 “over limit” conversions before O.S. is set to minimize false tripping in noisy environments. Default values set at power up. Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A LM75A www.ti.com SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 6.6 Digital DC Characteristics Unless otherwise noted, these specifications apply for +VS = 2.7 to 5.5 Vdc for LM75AIM and LM75AIMM. TA = TJ = 25°C, unless otherwise noted. PARAMETER VIN(1) VIN(0) TEST CONDITIONS Logical “1” Input Voltage Logical “0” Input Voltage MIN –55°C ≤ TJ ≤ 125°C +VS × 0.7 –55°C ≤ TJ ≤ 125°C −0.3 TYP (1) MAX (2) V +VS + 0.3 V V +VS × 0.3 VIN = +VS V 0.005 1.0 μA −1.0 μA IIN(1) Logical “1” Input Current IIN(0) Logical “0” Input Current CIN All Digital Inputs IOH High Level Output Current Open drain leakage VOL Low Level Output Voltage IOL = 3 mA, –55°C ≤ TJ ≤ 125°C 0.4 Output Fall Time CL = 400 pF IO = 3 mA, –55°C ≤ TJ ≤ 125°C 250 tOF VIN = +VS, –55°C ≤ TJ ≤ 125°C −0.005 VIN = 0 V (1) (2) UNIT VIN = 0 V, –55°C ≤ TJ ≤ 125°C 5 LM75A pF VOH = 5 V, –55°C ≤ TJ ≤ 125°C μA 1 V ns Typicals are at TA = 25°C and represent most likely parametric norm. Maximum values (limits) are ensured to AOQL (Average Outgoing Quality Level). 6.7 I2C Digital Switching Characteristics Unless otherwise noted, these specifications apply for +VS = 2.7 to 5.5 Vdc for LM75AIM and LM75AIMM on output lines = 80 pF unless otherwise specified. TA = TJ = 25°C, unless otherwise noted. PARAMETER TEST CONDITIONS MIN TYP (1) MAX (2) (3) UNIT t1 SCL (Clock) Period –55°C ≤ TJ ≤ 125°C 2.5 ns t2 Data in Set-Up Time to SCL High –55°C ≤ TJ ≤ 125°C 100 ns t3 Data Out Stable after SCL Low –55°C ≤ TJ ≤ 125°C 0 ns t4 SDA Low Set-Up Time to SCL Low (Start Condition) –55°C ≤ TJ ≤ 125°C 100 t5 SDA High Hold Time after SCL High (Stop Condition) –55°C ≤ TJ ≤ 125°C 100 tTIMEOUT SDA Time Low for Reset of Serial LM75A Interface (4) (1) (2) (3) (4) ns ns 75 –55°C ≤ TJ ≤ 125°C 325 ms Typicals are at TA = 25°C and represent most likely parametric norm. Maximum values (limits) are ensured to AOQL (Average Outgoing Quality Level). Timing specifications are tested at the bus input logic levels (Vin(0)=0.3XVA for a falling edge and Vin(1)=0.7XVA for a rising edge) when the SCL and SDA edge rates are similar. Holding the SDA line low for a time greater than tTIMEOUT will cause the LM75A to reset SDA to the IDLE state of the serial bus communication (SDA set High). Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A 5 LM75A SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 www.ti.com Figure 1. Timing Diagram Figure 2. Temperature-to-Digital Transfer Function (Non-Linear Scale for Clarity) Figure 3. Printed Circuit Board Used for Thermal Resistance Specifications 6 Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A LM75A www.ti.com SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 Figure 4. I2C Timing Diagram Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A 7 LM75A SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 www.ti.com Figure 5. I2C Timing Diagrams (Continued) 8 Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A LM75A www.ti.com SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 6.8 Typical Characteristics Figure 6. Accuracy vs Temperature (LM75A) Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A 9 LM75A SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 www.ti.com 7 Detailed Description 7.1 Overview The LM75A temperature sensor incorporates a band-gap type temperature sensor and 9-bit ADC (sigma-delta ADC). The temperature data output of the LM75A is available at all times via the I2C bus. If a conversion is in progress, it will be stopped and restarted after the read. A digital comparator is also incorporated that compares a series of readings, the number of which is user-selectable, to user-programmable setpoint and hysteresis values. The comparator trips the O.S. output line, which is programmable for mode and polarity. The LM75A has an integrated low-pass filter on both the SDA and the SCL line. These filters increase communications reliability in noisy environments. The LM75A also has a bus fault timeout feature. If the SDA line is held low for longer than tTIMEOUT (see specification) the LM75A will reset to the IDLE state (SDA set to high impedance) and wait for a new start condition. The TIMEOUT feature is not functional in Shutdown Mode. 7.2 Functional Block Diagram +VS 8 Ð 1-Bit D/A TOS Set Point Register A0 A1 Set Point Comparator A2 Reset Configuration Register Pointer Register 5 THYST Set Point Register Product ID Register 1 7 6 O.S. Threshold 9-Bit Sigma-Delta ADC Silicon Bandgap Temperature Sensor 3 Temperature 10-Bit Digital Decimation Filter Two-Wire Interface 2 SDA SCL 4 GND 7.3 Feature Description 7.3.1 Digital Temperature Sensor The LM75A is an industry-standard digital temperature sensor with an integrated sigma-delta ADC and I2C interface. The LM75A provides 9-bit digital temperature readings with an accuracy of ±2°C from –25°C to 100°C and ±3°C over –55°C to 125°C. The LM75A operates with a single supply from +2.7 V to +5.5 V. Communication is accomplished over a 2-wire interface which operates up to 400kHz. The LM75A has three address pins, allowing up to eight LM75A devices to operate on the same 2-wire bus. The LM75A has a dedicated over-temperature output (O.S.) with programmable limit and hysteresis. This output has programmable fault tolerance, which allows the user to define the number of consecutive error conditions that must occur before O.S. is activated. 7.4 Device Functional Modes In Comparator mode the O.S. Output behaves like a thermostat. The output becomes active when temperature exceeds the TOS limit, and leaves the active state when the temperature drops below the THYST limit. In this mode the O.S. output can be used to turn a cooling fan on, initiate an emergency system shutdown, or reduce system clock speed. Shutdown mode does not reset O.S. state in a comparator mode. In Interrupt mode exceeding TOS also makes O.S. active but O.S. will remain active indefinitely until reset by reading any register via the I2C interface. Once O.S. has been activated by crossing TOS, then reset, it can be activated again only by Temperature going below THYST. Again, it will remain active indefinitely until being reset by a read. Placing the LM75A in shutdown mode also resets the O.S. Output. 10 Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A LM75A www.ti.com SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 Device Functional Modes (continued) The LM75A always powers up in a known state. The power up default conditions are: • Comparator mode • TOS = 80°C • THYST = 75°C • O.S. active low • Pointer = “00” When the supply voltage is less than about 1.7V, the LM75A is considered powered down. As the supply voltage rises above the nominal 1.7V power up threshold, the internal registers are reset to the power up default values listed above. If the LM75A is not connected to the I2C bus on power up, it will act as a stand-alone thermostat with the power up default conditions listed above. It is optional, but recommended, to connect the address pins (A2, A1, A0) and the SCL and SDA pins together and to a 10k pullup resistor to +VS for better noise immunity. Any of these pins may also be tied high separately through a 10-k pullup resistor. 7.5 Programming 7.5.1 I2C Bus Interface The LM75A operates as a slave on the I2C bus, so the SCL line is an input (no clock is generated by the LM75A) and the SDA line is a bi-directional serial data path. According to I2C bus specifications, the LM75A has a 7-bit slave address. The four most significant bits of the slave address are hard wired inside the LM75A and are “1001”. The three least significant bits of the address are assigned to pins A2–A0, and are set by connecting these pins to ground for a low, (0); or to +VS for a high, (1). Therefore, the complete slave address is: 1 0 0 1 A2 A1 MSB A0 LSB These interrupt mode resets of O.S. occur only when LM75A is read or placed in shutdown. Otherwise, O.S. would remain active indefinitely for any event. Figure 7. O.S. Output Temperature Response Diagram Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A 11 LM75A SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 www.ti.com 7.5.2 Temperature Data Format Temperature data can be read from the Temperature, TOS Set Point, and THYST Set Point registers; and written to the TOS Set Point, and THYST Set Point registers. Temperature data is represented by a 9-bit, two's complement word with an LSB (Least Significant Bit) equal to 0.5°C: Temperature Digital Output Binary Hex +125°C 0 1111 1010 0FAh +25°C 0 0011 0010 032h +0.5°C 0 0000 0001 001h 0°C 0 0000 0000 000h −0.5°C 1 1111 1111 1FFh −25°C 1 1100 1110 1CEh −55°C 1 1001 0010 192h 7.5.3 Shutdown Mode Shutdown mode is enabled by setting the shutdown bit in the Configuration register via the I2C bus. Shutdown mode reduces power supply current significantly. See specified quiescent current specification in the electrical tables. In Interrupt mode O.S. is reset if previously set and is undefined in Comparator mode during shutdown. The I2C interface remains active. Activity on the clock and data lines of the I2C bus may slightly increase shutdown mode quiescent current. TOS, THYST, and Configuration registers can be read from and written to in shutdown mode. For the LM75A, the TIMEOUT feature is turned off in Shutdown Mode. 7.5.4 Fault Queue A fault queue of up to 6 faults is provided to prevent false tripping of O.S. when the LM75A is used in noisy environments. The number of faults set in the queue must occur consecutively to set the O.S. output. 7.5.5 Comparator and Interrupt Mode As indicated in the O.S. Output Temperature Response Diagram, Figure 7, the events that trigger O.S. are identical for either Comparator or Interrupt mode. The most important difference is that in Interrupt mode the O.S. will remain set indefinitely once it has been set. To reset O.S. while in Interrupt mode, perform a read from any register in the LM75A. 7.5.6 O.S. Output The O.S. output is an open-drain output and does not have an internal pullup. A “high” level will not be observed on this pin until pullup current is provided from some external source, typically a pullup resistor. Choice of resistor value depends on many system factors but, in general, the pullup resistor should be as large as possible. This will minimize any errors due to internal heating of the LM75A. The maximum resistance of the pullup, based on LM75A specification for High Level Output Current, to provide a 2-V high level, is 30 kΩ. 7.5.7 O.S. Polarity The O.S. output can be programmed via the configuration register to be either active low (default mode), or active high. In active low mode the O.S. output goes low when triggered exactly as shown on the O.S. Output Temperature Response Diagram, Figure 7. Active high simply inverts the polarity of the O.S. output. 12 Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A LM75A www.ti.com SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 7.5.8 Internal Register Structure SCL 2 I C Interface SDA Data Address Pointer Register (Selects register for communication) Temperature (Read-Only) Pointer = 00000000 Configuration (Read-Write) Pointer = 00000001 TOS Set Point (Read-Write) Pointer = 00000011 THYST Set Point (Read-Write) Pointer = 00000010 Product ID (Read-Only) Pointer = 00000111 Figure 8. Register Structure There are four data registers in the LM75A and an additional Product ID register selected by the Pointer register. At power-up the Pointer is set to “000”; the location for the Temperature Register. The Pointer register latches whatever the last location it was set to. In Interrupt Mode, a read from the LM75A, or placing the device in shutdown mode, resets the O.S. output. All registers are read and write, except the Temperature register and the LM75A's Product ID register, which are read-only. A write to the LM75A will always include the address byte and the Pointer byte. A write to the Configuration register requires one data byte, and the TOS and THYST registers require two data bytes. Reading the LM75A can take place either of two ways: If the location latched in the Pointer is correct (most of the time it is expected that the Pointer will point to the Temperature register because it will be the data most frequently read from the LM75A), then the read can simply consist of an address byte, followed by retrieving the corresponding number of data bytes. If the Pointer needs to be set, then an address byte, pointer byte, repeat start, and another address byte will accomplish a read. 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 indicates an overtemperature condition, the host processor could immediately take action to remedy the excessive temperatures. At the end of a read, the LM75A can accept either Acknowledge or No Acknowledge from the Master (No Acknowledge is typically used as a signal for the slave that the Master has read its last byte). 7.6 Register Maps 7.6.1 Pointer Register (Selects Which Registers Will Be Read From or Written to): P7 P6 P5 P4 P3 0 0 0 0 0 P2 P1 P0 Register Select P0-P1: Register Select: P2 P1 P0 0 0 0 Temperature (Read-only) (Power-up default) Register 0 0 1 Configuration (Read/Write) 0 1 0 THYST (Read/Write) 0 1 1 TOS (Read/Write) 1 1 1 Product ID Register Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A 13 LM75A SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 www.ti.com P3–P7: Must be kept zero. 7.6.2 Temperature Register (Read-Only): D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 MSB Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB X X X X X X X D0–D6: Undefined. D7–D15: Temperature Data. One LSB = 0.5°C. Two's complement format. 7.6.3 Configuration Register (Read/Write): D7 D6 D5 0 0 0 D4 D3 Fault Queue D2 D1 D0 O.S. Polarity Cmp/Int Shutdown Power up default is with all bits “0” (zero). D0: Shutdown: When set to 1 the LM75A goes to low power shutdown mode. D1: Comparator/Interrupt mode: 0 is Comparator mode, 1 is Interrupt mode. D2: O.S. Polarity: 0 is active low, 1 is active high. O.S. is an open-drain output under all conditions. D3–D4: Fault Queue: Number of faults necessary to detect before setting O.S. output to avoid false tripping due to noise. Faults are determine at the end of a conversion. See specified temperature conversion time in the electrical tables. D4 D3 Number of Faults 0 0 1 (Power-up default) 0 1 2 1 0 4 1 1 6 D5–D7: These bits are used for production testing and must be kept zero for normal operation. 7.6.4 THYST and TOS Register (Read/Write): D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 MSB Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB X X X X X X X D0–D6: Undefined 75°C D7–D15: THYST Or TOS Trip Temperature Data. Power up default is TOS = 80°C, THYST = 7.6.5 PRODID: Product ID Register (Read-Only) Pointer Address: 07h D7 D6 D5 D4 D3 D2 D1 D0 1 0 1 0 0 0 0 1 D4--D7 Product Identification Nibble. Always returns Ah to uniquely identify this part as the LM75A. D0--D3 Die Revision Nibble. Returns 1h to uniquely identify the revision level as one. 14 Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A LM75A www.ti.com SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 8 Application and Implementation NOTE Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality. 8.1 Application Information The wide temperature and supply range and I2C interface make the LM75A ideal for a number of applications including base stations, electronic test equipment, office electronics, personal computers, and any other system where thermal management is critical to performance. 8.2 Typical Applications 8.2.1 Simple Fan Controller, Interface Optional +VS +12V Optional but Recommended Pull-up In Stand-alone Mode R3 10k C1 100 nF R1 10k R2 10k +12V/300 mA Fan Motor 8 A0 7 A1 6 3 O.S. A2 5 Q1 2N3904 Q2 NDP410A series LM75A SDA 1 SCL 2 4 GND When using the two-wire interface: program O.S. for active high and connect O.S. directly to Q2's gate. Figure 9. Simple Fan Controller, Interface Optional 8.2.1.1 Design Requirements The LM75A requires positive supply voltage of 2.7 V to 5.5 V to be applied between +Vs and GND. For best results, bypass capacitors of 100 nF and 10 µF are recommended. Pullup resistors of 10 kΩ are required on SCL and SDA. 8.2.1.2 Detailed Design Procedure Accessing the conversion result of the LM75A consists of writing an address byte followed by retrieving the corresponding number of data bytes. The first data byte is the most significant byte with the 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 indicates an overtemperature condition, the host processor could immediately take action to remedy the excessive temperatures. At the end of a read, the LM75A can accept either Acknowledge or No Acknowledge from the Master (No Acknowledge is typically used as a signal for the slave that the Master has read its last byte). Temperature data is two's complement format and one LSB is equivalent to 0.5°C. Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A 15 LM75A SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 www.ti.com Typical Applications (continued) 8.2.1.3 Application Curve Figure 10. Temperature Accuracy 8.3 System Examples 8.3.1 Simple Thermostat, Interface Optional + 5 VDC Heater Heater Supply Optional but Recommended Pull-up In Stand-alone Mode C1 100 nF R2 10k 8 R1 +VS 10k K1 5V Relay D1 1N4001 A0 7 A1 6 A2 5 LM75A 3 O.S. Q1 2N2222A SDA 1 SCL 2 4 GND Figure 11. Simple Thermostat, Interface Optional 16 Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A LM75A www.ti.com SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 System Examples (continued) 8.3.2 Temperature Sensor with Loudmouth Alarm (Barking Watchdog) +VS Optional but Recommended Pull-up In Stand-alone Mode R3 10k C6 100 nF R1 10k 8 A0 7 A1 6 3 A2 5 LM75A SDA 1 SCL 2 4 GND SHUTDOWN Vo2 BYPASS C1 100 nF C2 100 nF +IN -IN GND VDD LM4861M Vo1 R5 200k O.S. C3 6.8 nF C4 6.8 nF C5 6.8 nF R2 10k R3 10k R4 10k Figure 12. Temperature Sensor with Loudmouth Alarm (Barking Watchdog) Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A 17 LM75A SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 www.ti.com 9 Power Supply Recommendations The LM75A is specified for operation from 2.7 V to 5.5 V. Place 100-nF and 10-µF capacitors close to +Vs in order to reduce errors coupling in from noisy or high impedance supplies. 10 Layout 10.1 Layout Guidelines To achieve the expected results when measuring temperature with an integrated circuit temperature sensor like the LM75A, it is important to understand that the sensor measures its own die temperature. For the LM75A, the best thermal path between the die and the outside world is through the LM75A's pins. In the VSSOP-8 package, the GND pin is directly connected to the die, so the GND pin provides the best thermal path. If the other pins are at different temperatures (unlikely, but possible), they will affect the die temperature, but not as strongly as the GND pin. In the SOIC-8 package, none of the pins is directly connected to the die, so they will all contribute similarly to the die temperature. Because the pins represent a good thermal path to the LM75A die, the LM75A will provide an accurate measurement of the temperature of the printed circuit board on which it is mounted. There is a less efficient thermal path between the plastic package and the LM75A die. If the ambient air temperature is significantly different from the printed circuit board temperature, it will have a small effect on the measured temperature. In probe-type applications, the LM75A can be mounted inside a sealed-end metal tube, and can then be dipped into a bath or screwed into a threaded hole in a tank. As with any IC, the LM75A and accompanying wiring and circuits must be kept insulated and dry, to avoid leakage and corrosion. This is especially true if the circuit may operate at cold temperatures where condensation can occur. Printed-circuit coatings and varnishes such as Humiseal and epoxy paints or dips are often used to insure that moisture cannot corrode the LM75A or its connections. 10.1.1 Digital Noise Issues The LM75A features an integrated low-pass filter on both the SCL and the SDA digital lines to mitigate the effects of bus noise. Although this filtering makes the LM75A communication robust in noisy environments, good layout practices are always recommended. Minimize noise coupling by keeping digital traces away from switching power supplies. Also, ensure that digital lines containing high-speed data communications cross at right angles to the SDA and SCL lines. Excessive noise coupling into the SDA and SCL lines on the LM75A—specifically noise with amplitude greater than 400 mVpp (the LM75A’s typical hysteresis), overshoot greater than 300mV above +Vs, and undershoot more than 300 mV below GND—may prevent successful serial communication with the LM75A. Serial bus no-acknowledge is the most common symptom, causing unnecessary traffic on the bus. Although the serial bus maximum frequency of communication is only 400 kHz, care must be taken to ensure proper termination within a system with long printed circuit board traces or multiple parts on the bus. 18 Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A LM75A www.ti.com SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 10.2 Layout Example Figure 13. Printed Circuit Board Used for Thermal Resistance Specifications Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A 19 LM75A SNOS808P – JANUARY 2000 – REVISED DECEMBER 2014 www.ti.com 11 Device and Documentation Support 11.1 Trademarks All trademarks are the property of their respective owners. 11.2 Electrostatic Discharge Caution These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 11.3 Glossary SLYZ022 — TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 12 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. 20 Submit Documentation Feedback Copyright © 2000–2014, Texas Instruments Incorporated Product Folder Links: LM75A PACKAGE OPTION ADDENDUM www.ti.com 10-Dec-2020 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) LM75AIM/NOPB ACTIVE SOIC D 8 95 RoHS & Green SN Level-1-260C-UNLIM -55 to 125 LM75 AIM LM75AIMM/NOPB ACTIVE VSSOP DGK 8 1000 RoHS & Green SN Level-1-260C-UNLIM -55 to 125 T00A LM75AIMME/NOPB ACTIVE VSSOP DGK 8 250 RoHS & Green SN Level-1-260C-UNLIM -55 to 125 T00A LM75AIMMX/NOPB ACTIVE VSSOP DGK 8 3500 RoHS & Green SN Level-1-260C-UNLIM -55 to 125 T00A LM75AIMX/NOPB ACTIVE SOIC D 8 2500 RoHS & Green SN Level-1-260C-UNLIM -55 to 125 LM75 AIM (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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