SNAS207B May   2004  – January 2024 LM64

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 Operating Ratings
    3. 5.3 DC Electrical Characteristics
    4. 5.4 Operating Electrical Characteristics
    5. 5.5 AC Electrical Characteristics
    6. 5.6 Digital Electrical Characteristics
    7. 5.7 SMBus Logical Electrical Characteristics
    8. 5.8 SMBus Digital Switching Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Conversion Sequence
      2. 6.3.2  The ALERT Output
        1. 6.3.2.1 ALERT Output as a Temperature Comparator
        2. 6.3.2.2 ALERT Output as an Interrupt
        3. 6.3.2.3 ALERT Output as an SMBus ALERT
      3. 6.3.3  SMBus Interface
      4. 6.3.4  Power-On Reset (POR) Default States
      5. 6.3.5  Temperature Data Format
      6. 6.3.6  Open-Drain Outputs, Inputs, and Pull-Up Resistors
      7. 6.3.7  Diode Fault Detection
      8. 6.3.8  Communicating with the LM64
      9. 6.3.9  Digital Filter
      10. 6.3.10 Fault Queue
      11. 6.3.11 One-Shot Register
      12. 6.3.12 Serial Interface Reset
  8. 7 Registers
    1. 7.1 LM64 Registers
      1. 7.1.1 LM64 Register Map in Hexadecimal Order
      2. 7.1.2 LM64 Register Map in Functional Order
      3. 7.1.3 LM64 Initial Register Sequence and Register Descriptions in Functional Order
        1. 7.1.3.1 LM64 Required Initial Fan Control Register Sequence
      4. 7.1.4 LM64 Register Descriptions in Functional Order
        1. 7.1.4.1 Fan Control Registers
        2. 7.1.4.2 Configuration Register
        3. 7.1.4.3 Tachometer Count And Limit Registers
        4. 7.1.4.4 Local Temperature And Local High Setpoint Registers
        5. 7.1.4.5 Remote Diode Temperature, Offset And Setpoint Registers
        6. 7.1.4.6 ALERT Status And Mask Registers
        7. 7.1.4.7 Conversion Rate And One-Shot Registers
        8. 7.1.4.8 ID Registers
    2. 7.2 General Purpose Registers
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Fan Control Duty Cycle VS. Register Settings and Frequency
        1. 8.1.1.1 Computing Duty Cycles for a Given Frequency
      2. 8.1.2 Use of the Lookup Table for Non-Linear PWM Values VS Temperature
      3. 8.1.3 NON-Ideality Factor and Temperature Accuracy
        1. 8.1.3.1 Diode Non_Ideality
        2. 8.1.3.2 Compensating for Diode Non-Ideality
      4. 8.1.4 Computing RPM of the Fan from the TACH Count
    2. 8.2 Typical Application
  10. 9 Layout
    1. 9.1 PCB Layout for Minimizing Noise
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

6.3.1 Conversion Sequence

The LM64 takes approximately 31.25 ms to convert the Local Temperature (LT), Remote Temperature (RT), and to update all of its registers. The Conversion Rate may be modified using the Conversion Rate Register. When the conversion rate is modified a delay is inserted between conversions, the actual conversion time remains at 31.25 ms. Different Conversion Rates will cause the LM64 to draw different amounts of supply current as shown in Figure 6-1.

GUID-6A11D92C-362B-4064-8B29-D193F3960C73-low.gifFigure 6-1 Supply Current vs Conversion Rate