SNAS207B
May 2004 – January 2024
LM64
PRODUCTION DATA
1
1
Features
2
Applications
3
Description
4
Pin Configuration and Functions
5
Specifications
5.1
Absolute Maximum Ratings
5.2
Operating Ratings
5.3
DC Electrical Characteristics
5.4
Operating Electrical Characteristics
5.5
AC Electrical Characteristics
5.6
Digital Electrical Characteristics
5.7
SMBus Logical Electrical Characteristics
5.8
SMBus Digital Switching Characteristics
6
Detailed Description
6.1
Overview
6.2
Functional Block Diagram
6.3
Feature Description
6.3.1
Conversion Sequence
6.3.2
The ALERT Output
6.3.2.1
ALERT Output as a Temperature Comparator
6.3.2.2
ALERT Output as an Interrupt
6.3.2.3
ALERT Output as an SMBus ALERT
6.3.3
SMBus Interface
6.3.4
Power-On Reset (POR) Default States
6.3.5
Temperature Data Format
6.3.6
Open-Drain Outputs, Inputs, and Pull-Up Resistors
6.3.7
Diode Fault Detection
6.3.8
Communicating with the LM64
6.3.9
Digital Filter
6.3.10
Fault Queue
6.3.11
One-Shot Register
6.3.12
Serial Interface Reset
7
Registers
7.1
LM64 Registers
7.1.1
LM64 Register Map in Hexadecimal Order
7.1.2
LM64 Register Map in Functional Order
7.1.3
LM64 Initial Register Sequence and Register Descriptions in Functional Order
7.1.3.1
LM64 Required Initial Fan Control Register Sequence
7.1.4
LM64 Register Descriptions in Functional Order
7.1.4.1
Fan Control Registers
7.1.4.2
Configuration Register
7.1.4.3
Tachometer Count And Limit Registers
7.1.4.4
Local Temperature And Local High Setpoint Registers
7.1.4.5
Remote Diode Temperature, Offset And Setpoint Registers
7.1.4.6
ALERT Status And Mask Registers
7.1.4.7
Conversion Rate And One-Shot Registers
7.1.4.8
ID Registers
7.2
General Purpose Registers
8
Application and Implementation
8.1
Application Information
8.1.1
Fan Control Duty Cycle VS. Register Settings and Frequency
8.1.1.1
Computing Duty Cycles for a Given Frequency
8.1.2
Use of the Lookup Table for Non-Linear PWM Values VS Temperature
8.1.3
NON-Ideality Factor and Temperature Accuracy
8.1.3.1
Diode Non_Ideality
8.1.3.2
Compensating for Diode Non-Ideality
8.1.4
Computing RPM of the Fan from the TACH Count
8.2
Typical Application
9
Layout
9.1
PCB Layout for Minimizing Noise
10
Device and Documentation Support
10.1
Documentation Support
10.2
Receiving Notification of Documentation Updates
10.3
Support Resources
10.4
Trademarks
10.5
Electrostatic Discharge Caution
10.6
Glossary
11
Revision History
12
Mechanical, Packaging, and Orderable Information
Package Options
Mechanical Data (Package|Pins)
NHW|24
MPQS003
Thermal pad, mechanical data (Package|Pins)
Orderable Information
snas207b_oa
snas207b_pm
1
Features
Accurately Senses Remote and Local Diode Temperatures
Integrated PWM Fan Speed Control Output
Programmable 8-step Lookup Table for Quieting Fans
ALERT
and
T_Crit
Open-drain Outputs
Tachometer Input for Measuring Fan RPM
10 bit Plus Sign Remote Diode Temperature Data Format, with 0.125°C Resolution
SMBus 2.0 Compatible Interface, Supports TIMEOUT
5 General Purpose Input/Output pins
5 General Purpose Default input pins
24-pin WQFN Package
Key Specifications:
Remote Diode Temperature Accuracy (includes quantization error)
Ambient Temp
30°C to 50°C
0°C to 85°C
Diode Temp
120°C to 140°C
25°C to 140°C
Max Error
±1.0°C (max)
±3.0°C (max)
Local Temp Accuracy (includes quantization error)
Ambient Temp 25°C to 125°C
Max Error ±3.0°C (max)
Power Supply Requirements
Supply DC Voltage 3.0 V to 3.6 V
Supply DC Current 1.1 mA (typ)