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)

2 Applications
• Computer Processor Thermal Management
• Graphics Processor Thermal Management
• Voltage Regulator Modules
• Electronic Instrumentation
• Power Supplies
• Projectors

3 Description
The LM64 is a remote diode temperature sensor
with PWM fan control. The LM64 accurately
measures its own temperature and that of a remote
diode. The LM64 remote temperature accuracy is
factory trimmed for a MMBT3904 diode-connected
transistor with a 16°C offset for high temperatures.
TACTUAL DIODE JUNCTION = TLM64 + 16°C
The LM64 features a PWM, open-drain, fan control
output, 5 GPIO (General Purpose Input/Output) and
5 GPD (General Purpose Default) pins. The 8-step
Lookup Table allows for a non-linear fan speed vs.
temperature transfer function often used to quiet
acoustic fan noise.