1FEATURES
23• Accurately Senses Diode-Connected 2N3904
Transistors or Thermal Diodes On Board Large
Processors or ASICs
• Accurately Senses its Own Temperature
• Factory Trimmed for Intel® Pentium® 4 and
Mobile Pentium 4 Processor-M Thermal Diodes
• Integrated PWM Fan Speed Control Output
• Acoustic Fan Noise Reduction With User-
Programmable 8-Step Lookup Table
• Multi-Function, User-Selectable Pin for Either nonALERT
Output, or Tachometer Input,
Functions width•
Tachometer Input for Measuring Fan RPM
• Smart-Tach Modes for Measuring RPM of Fans
With Pulse-Width-Modulated Power as Shown
in Typical Application
• Offset Register can Adjust for a Variety of
Thermal Diodes
• 10 Bit Plus Sign Remote Diode Temperature
Data Format, With 0.125°C Resolution
• SMBus 2.0 Compatible Interface, Supports
TIMEOUT
• LM86-Compatible Pinout
• LM86-Compatible Register Set
• 8-Pin SOIC Package

APPLICATIONS
• Computer Processor Thermal Management
(Laptop, Desktop, Workstations, Servers)
• Graphics Processor Thermal Management
• Electronic Test Equipment
• Projectors
• Office Equipment
• Industrial Controls

DESCRIPTION
The LM63 is a remote diode temperature sensor with
integrated fan control. The LM63 accurately
measures: (1) its own temperature and (2) the
temperature of a diode-connected transistor, such as
a 2N3904, or a thermal diode commonly found on
Computer Processors, Graphics Processor Units
(GPU) and other ASIC's. The LM63 remote
temperature sensor's accuracy is factory trimmed for
the series resistance and 1.0021 non-ideality of the
Intel 0.13 μm Pentium 4 and Mobile Pentium 4
Processor-M thermal diode. The LM63 has an offset
register to correct for errors caused by different nonALERT
ideality factors of other thermal diodes.
The LM63 also features an integrated, pulse-width•
modulated (PWM), open-drain fan control output. Fan
speed is a combination of the remote temperature
reading, the lookup table and the register settings. The 8-step Lookup Table enables the user to
program a non-linear fan speed vs. temperature
transfer function often used to quiet acoustic fan
noise.