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

7.1.4.6 ALERT Status And Mask Registers

ADDRESS
Hex		 Read/
Write		 Bits POR
Value		 Name Description
02HEX ALERT STATUS REGISTER (8-bits) (All Alarms are latched until read, then cleared if alarm condition was removed at the time of the read.)
0x02 Read Only 7 0 Busy When this bit is a 0, the ADC is not converting.
When this bit is set to a 1, the ADC is performing a conversion. This bit does not affect ALERT status.
6 0 Local
High Alarm		 When this bit is a 0, the internal temperature of the LM64 is at or below the Local High Setpoint.
When this bit is a 1, the internal temperature of the LM64 is above the Local High Setpoint, and an ALERT is triggered.
5 0 This bit is unused and always read as 0.
4 0 Remote
High Alarm		 When this bit is a 0, the temperature of the Remote Diode is at or below the Remote High Setpoint.
When this bit is a 1, the temperature of the Remote Diode is above the Remote High Setpoint, and an ALERT is triggered.
3 0 Remote
Low Alarm		 When this bit is a 0, the temperature of the Remote Diode is at or above the Remote Low Setpoint.
When this bit is a 1, the temperature of the Remote Diode is below the Remote Low Setpoint, and an ALERT is triggered.
2 0 Remote Diode
Fault Alarm		 When this bit is a 0, the Remote Diode appears to be correctly connected.
When this bit is a 1, the Remote Diode may be disconnected or shorted. This Alarm does not trigger an ALERT.
1 0 Remote
T_CRIT Alarm		 When this bit is a 0, the temperature of the Remote Diode is at or below the T_CRIT Limit.
When this bit is a 1, the temperature of the Remote Diode is above the T_CRIT Limit, and an ALERT is triggered.
0 0 Tach Alarm When this bit is a 0, the Tachometer count is lower than or equal to the Tachometer Limit (the RPM of the fan is greater than or equal to the minimum desired RPM).
When this bit is a 1, the Tachometer count is higher than the Tachometer Limit (the RPM of the fan is less than the minimum desired RPM), and an ALERT is triggered.
16HEX ALERT MASK REGISTER (8-bits)
16 R/W 7 1 This bit is unused and always read as 1.
6 0 Local High
Alarm Mask		 When this bit is a 0, a Local High Alarm event will generate an ALERT.
When this bit is a 1, a Local High Alarm will not generate an ALERT
5 1 This bit is unused and always read as 1.
4 0 Remote
High Alarm Mask		 When this bit is a 0, Remote High Alarm event will generate an ALERT.
When this bit is a 1, a Remote High Alarm event will not generate an ALERT.
3 0 Remote
Low Alarm
Mask		 When this bit is a 0, a Remote Low Alarm event will generate an ALERT.
When this bit is a 1, a Remote Low Alarm event will not generate an ALERT.
2 1 This bit is unused and always read as 1.
1 0 Remote
T_CRIT
Alarm Mask		 When this bit is a 0, a Remote T_CRIT event will generate an ALERT.
When this bit is a 1, a Remote T_CRIT event will not generate an ALERT.
0 0 Tach
Alarm Mask		 When this bit is a 0, a Tach Alarm event will generate an ALERT.
When this bit is a 1, a Tach Alarm event will not generate an ALERT.