TC654

Features:

• Temperature Proportional Fan Speed for Reduced Acoustic Noise and Longer Fan Life
• FanSense™ Protects against Fan Failure and Eliminates the Need for 3-wire Fans
• Over Temperature Detection (TC655)
• Efficient PWM Fan Drive
• Provides RPM Data
• 2-Wire SMBus™-Compatible Interface
• Supports Any Fan Voltage
• Software Controlled Shutdown Mode for "Green" Systems
• Supports Low Cost NTC/PTC Thermistors
• Space Saving 10-Pin MSOP Package
• Temperature Range: -40to +85




Application

• Personal Computers & Servers
• LCD Projectors
• Datacom & Telecom Equipment
• Fan Trays
• File Servers
• Workstations
• General Purpose Fan Speed Control




Pinout






Specifications

Parameter NameValueTypical Accuracy (°C)Depends on external thermistorOver Temp AlertNOSM BusyesPredictive Fan FaultyesMax. Supply Current (A)320Max. Accuracy @ 25°C (°C)Depends on external thermistorIntegrated Temp SensorNoFan SenseYesExternal Temp InputYesAuto ShutdownNoDevice DescriptionDual SMBus Fan ManagerTemp Range (°C)-40 to +85Vcc Range (V)+3.0 to +5.5

V_DD..................................................................................6.5 V
Input Voltages .................................... -0.3 V to (V_DD + 0.3 V)
Output Voltages .................................. -0.3 V to (V_DD + 0.3 V)
Storage temperature ......................................-65 to +150
Ambient temp. with power applied .................-40 to +125
Maximum Junction Temperature, T_J ................................ 150
ESD protection on all pins.............................................. 4 kV


*Notice: Stresses above those listed under "Maximum ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operational listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability.

Description

The TC654 is a dual PWM mode fan speed controller with FanSense™ TM technology for use with brush-less DC motors. The device allows temperature proportional speed control and therefore accomplishes lower acoustic fan noise and longer fan life. The TC654 reads the voltage provided by an external ther-mistor (or voltage output temperature sensor) and adjusts a 30% to 100% PWM duty cycle output to the fan with respect to the input temperature voltage. The PWM duty cycle can also be programmed via SMBus to allow fan speed control without the need of an external thermistor.

In normal fan operation, pulse trains are present at the SENSE pin. These pulses are used to calculate the fan RPM. The fan RPM data is used to detect a worn out, stalled, open or unconnected fan. An RPM level below the user-programmable threshold causes the TC654 to assert a logic low alert signal (FAULT). Thedefault value is 500RPM. The TC654 consumes only 0.3mA during operation and can also enter a low-power shutdown mode by setting the appropriate bit in the configuration register.