Texas Instruments LM64EVAL

Overview

LM64EVAL from National Semiconductor (now Texas Instruments) is an evaluation board designed to demonstrate and validate the LM64 Remote Diode Temperature Sensor with integrated fan control functionality. It includes a fully assembled PCBA featuring the LM64CILQ sensor, Cypress CY7C64603-52NC USB microcontroller, AT24C02 EEPROM, LP2950CDT-3.3 voltage regulator, and on-board MMBT3904 remote diode emulator - enabling real-time local/remote temperature monitoring, PWM fan speed control, tachometer feedback, and SMBus register access via USB.

For engineers reviewing the LM64EVAL datasheet, LM64EVAL pinout, LM64EVAL application, or LM64EVAL equivalent, this kit supports rapid validation of thermal management in PC, server, and embedded systems requiring dual-diode temperature sensing, programmable fan profiles, and SMBus-based system monitoring - with full software control via SensorEval GUI and register-level configuration.

Technical Context

The LM64EVAL implements a complete SMBus 2.0-compliant thermal monitoring system: the LM64CILQ sensor interfaces directly to the Cypress CY7C64603-52NC USB bridge IC, which handles host communication, register mapping, and USB enumeration. The board provides hardware-accessible GPIO/GPD headers, configurable ALERT#/TCRIT outputs, and jumper-selectable A0 address pin for multi-device SMBus bus testing.

It integrates analog signal conditioning for remote diode inputs (D+/D−), active fan power delivery (5 V or 12 V via J2), tachometer input circuitry, and on-board 3.3 V regulation - all synchronized to a 12 MHz crystal oscillator. SensorEval software enables full read/write access to LM64 registers including temperature conversion results (Registers 00–03), fan control setup (Registers 4A–4F), and critical limit thresholds (Registers 20–23).

Key Specifications

Availability

LM64EVAL is available at Aetrix Electronics and suitable for PC motherboard validation, server thermal subsystem development, embedded fan control prototyping, and SMBus device interoperability testing requiring stable component supply and legacy evaluation platform continuity.

Supply support for LM64EVAL includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

National Semiconductor, acquired by Texas Instruments in 2011, specialized in high-performance analog and mixed-signal semiconductors for power management, data conversion, and interface applications.

The LM64EVAL belongs to National Semiconductor's thermal monitoring evaluation platform family, developed specifically to accelerate design-in of the LM64 series for PC, server, and telecom equipment requiring precise dual-point temperature measurement and intelligent fan control.

FAQ

What is the primary function of the LM64EVAL evaluation board?

The LM64EVAL evaluation board is a complete hardware-software platform for evaluating the LM64CILQ remote diode temperature sensor with integrated fan control. It enables engineers to verify temperature measurement accuracy, configure SMBus registers, test PWM fan drive behavior, monitor tachometer feedback, and validate system-level thermal management logic - all through the SensorEval GUI running on a Windows PC connected via USB.

Does the LM64EVAL require an external power supply to operate?

Yes - the LM64EVAL requires two power sources: USB power (5 V) for the Cypress microcontroller, EEPROM, and LM64 logic; and an external DC power supply (5 V or 12 V) connected to header J2 to drive the fan under test. The board includes onboard regulation to generate 3.3 V for the LM64 and supporting circuitry, but fan power must be supplied externally as specified in Section 2.1 of the User's Guide.

Can the LM64EVAL be used without the SensorEval software?

No - the LM64EVAL relies entirely on the SensorEval software (provided on CD with the kit) to communicate with the Cypress USB bridge IC and access LM64 registers. While the hardware is fully functional, there is no standalone firmware or command-line interface; all configuration, temperature reads, fan control, and alert monitoring must be performed through SensorEval's graphical interface on Windows 98/2000/XP.

What components are included in the LM64EVAL kit?

The LM64EVAL kit includes: (1) the LM64 Evaluation Board (PCBA), (2) SensorEval Software CD containing readme.txt, installer, manual, and User's Guide, and (3) jumpers for GPD/GPIO testing. It does not include the USB cable or fan - those must be sourced separately per Section 2.1 of the User's Guide.

Is the LM64EVAL compatible with modern Windows operating systems?

The LM64EVAL was validated for Windows 98/2000/XP only. While it may function on newer Windows versions via compatibility mode or manual driver installation, National Semiconductor did not release updated drivers or SensorEval builds for Windows 7+, and USB enumeration or GUI responsiveness cannot be guaranteed. For production use, TI recommends verifying operation in target OS environments prior to integration.