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.