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

7.1.4.5 Remote Diode Temperature, Offset And Setpoint Registers

ADDRESS
Hex		Read/
Write		BitsPOR
Value		NameDescription
01Read Only7:0N/ARemote Diode
Temperature
Reading (MSB)		This is the MSB of the LM64 remote diode temperature value, 2’s complement. Bit 7 is the sign bit, bit 6 has a weight 64°C, and bit 0 has a weight of 1°C. Read this byte first. The actual remote diode temperature is 16°C higher than the values in registers 0x01 and 0x10.
10Read Only7:5N/ARemote Diode
Temperature
Reading (LSB)		This is the LSB of the LM64 remote diode temperature value, in 2’s complement. Bit 7 has a weight 0.5°C, bit 6 has a weight of 0.25°C, and bit 5 has a weight of 0.125°C. The actual remote diode temperature is 16°C higher than the values in registers 0x01 and 0x10.
4:000Always 00.
11R/W7:500Remote
Temperature
OFFSET (MSB)		These registers contain the offset value added to, or subtracted from, the remote diode’s reading to compensate for the different non-ideality factors of different processors, diodes, etc. The 2’s complement value, in these registers is added to the output of the LM64’s ADC to form the temperature reading contained in registers 01 and 10.
12R/W7:500Remote
Temperature
OFFSET (LSB)
4:000Always 00.
07 (0D)R/W7:00x46
(70°C)		Remote HIGH
Setpoint (MSB)		High setpoint temperature for remote diode. Same format as Remote Temperature Reading (registers 01 and 10).
13R/W7:500Remote HIGH
Setpoint (LSB)
4:000Always 00.
08 (0E)R/W7:000
(0°C)		Remote LOW
Setpoint (MSB)		Low setpoint temperature for remote diode. Same format as Remote Temperature Reading (registers 01 and 10).
14R/W7:500Remote LOW
Setpoint (LSB)
4:000Always 00.
19R/W7:00x55
(85°C)		Remote Diode
T_CRIT Limit		This 8-bit integer storing the T_CRIT limit is initially 85°C (101°C actual remote T_Crit limit). This value can be changed at any time after power-up.
21R/W7:00x0A
(10°C)		Remote Diode
T_CRIT
Hysteresis		8-bit integer storing T_CRIT hysteresis. T_CRIT stays activated until the remote diode temperature goes below [(T_CRIT Limit)—(T_CRIT Hysteresis)].
BFR/W7:300000These bits are unused and should always set to 0.
2:100Remote Diode
Temperature
Filter		00: Filter Disabled
01: Filter Level 1 (minimal filtering, same as 10)
10: Filter Level 1 (minimal filtering, same as 01)
11: Filter Level 2 (maximum filtering)
00Comparator
Mode		0: the ALERT pin functions as an Interrupt or ARA mode.
1: the ALERT pin behaves as a comparator, asserting itself when an ALERT condition exists, de-asserting itself when the ALERT condition goes away.