THMC50 Status:OBSOLETE

Product Information

Features

• Two-Wire SMBus Serial Interface
• 3.3 V Operation
• Low Operating and Standby Current
• Remote and Local Temperature Monitoring
• 0 V to 2.5 V, 8-bit DAC for Fan Speed Control
• Two Voltage Supervisors With Reset Functions
• Fault Tolerant Fan Control With Automatic Hardware Trip Point
• Bidirectional Thermal Overload Indicator
• ACPI Thermal Model Compliant

Intel and Pentium are registered trademarks of Intel Corporation.
Sun is a registered trademark and UltraSPARC is a trademark of Sun Microsystems.

Description

The THMC50 is a local/remote temperature monitor with two voltage supervisor circuits and an 8-bit, 0-V to 2.5-V DAC designed for temperature monitoring and fan control via a two-wire SMBus serial interface. The THMC50 is intended for use in personal computer applications according to the Advanced Configuration and Power Interface (ACPI) thermal model. The device is also suitable for use in network routers and hubs, office equipment, telephone switching networks, industrial control applications, and any other application requiring temperature monitoring, fan speed control, and two 3.3-V supply voltage supervisors.

Temperature data is reported in a 2s complement, 8-bit binary format. The local temperature sensor can be used to monitor the ambient temperature, while a remote thermal diode, such as the one present on the Intel^® Pentium^® II, III, and the Sun^® UltraSPARC^TM microprocessors, can be used to monitor the actual CPU die temperature. For applications not using a microprocessor with an integrated thermal diode, an inexpensive diode-connected 2N3904 NPN transistor can also be used to sense the remote temperature.

The THMC50 provides maskable interrupts for under/over temperature condition with default or user adjustable limit values. If the temperature limit values are exceeded, the THMC50 asserts INT\ low. If the default thermal limits are exceeded, the THERM\ terminal is asserted low, and the FAN_SPD analog output automatically goes to full-scale voltage to set the fan at maximum speed. THERM\ can also be used as an input to instantly command full fan speed.

The 8-bit, 0-2.5 V DAC output of the THMC50, along with an external amplifier circuit, provides the means to control the speed of a cooling fan. Fault tolerant fan-speed control is achieved through default and user-programmable values for high temperature limits that command the fan to full speed once the temperature limits are exceeded.

The THMC50 also provides two reset functions for the V_(VCC3AUX) and V_(VCC3) supply voltage. The reset functions are assured down to 1-V supply voltage.