TC654/TC655 M Dual SMBus PWM Fan Speed Controllers With Fan Fault Detection Features Description Temperature Proportional Fan Speed for The TC654 and TC655 are PWM mode fan speed con- Reduced Acoustic Noise and Longer Fan Life trollers with FanSense technology for use with brush- less DC fans. These devices implement temperature FanSense Protects against Fan Failure and proportional fan speed control which lowers acoustic Eliminates the Need for 3-wire Fans fan noise and increases fan life. The voltage at V IN Over Temperature Detection (TC655) (Pin 1) represents temperature and is typically pro- Efficient PWM Fan Drive vided by an external thermistor or voltage output tem- Provides RPM Data perature sensor. The PWM output (V ) is adjusted OUT 2-Wire SMBus-Compatible Interface between 30% and 100%, based on the voltage at V . IN The PWM duty cycle can also be programmed via Supports Any Fan Voltage SMBus to allow fan speed control without the need for Software Controlled Shutdown Mode forGree an external thermistor. If V is not connected, the IN Systems TC654/TC655 will start driving the fan at a default duty Supports Low Cost NTC/PTC Thermistors cycle of 39.33%. See Section 4.3,Fan Startu, for Space Saving 10-Pin MSOP Package more details. Temperature Range: -40C to +85C In normal fan operation, pulse trains are present at SENSE1 (Pin 8) and SENSE2 (Pin 7). The TC654/ Applications TC655 use these pulses to calculate the fan revolu- Personal Computers & Servers tions per minute (RPM). The fan RPM data is used to detect a worn out, stalled, open or unconnected fan. LCD Projectors An RPM level below the user-programmable threshold Datacom & Telecom Equipment causes the TC654/TC655 to assert a logic low alert Fan Trays signal (FAULT). The default threshold value is File Servers 500 RPM. Also, if this condition occurs, F1F (bit 0<0>) Workstations or F2F (bit 1<0>) in the Status Register will also be set to a 1. General Purpose Fan Speed Control An over-temperature condition is indicated when the Package Type voltage at V exceeds 2.6 V (typical). The TC654/ IN TC655 devices indicate this by setting OTF(bit 5<X>) in 10-Pin MSOP the Status Register to a 1 . The TC655 device also pulls the FAULT line low during an over-temperature condition. V 1 10 V IN DD The TC654/TC655 devices are available in a 10-Pin C 9 V 2 F OUT MSOP package and consume 150 A during opera- TC654 tion. The devices can also enter a low-power shutdown 8 SENSE1 SCLK 3 TC655 mode (5 A, typ.) by setting the appropriate bit in the Configuration Register. The operating temperature SDA 7 SENSE2 4 range for these devices is -40C to +85C. 5 6 FAULT GND SMBus is a trademark of Intel Corporation. 2002 Microchip Technology Inc. DS21734A-page 1TC654/TC655 Functional Block Diagram TC654/TC655 Note V OTF V V IN DD + OTF + Control + V OUT Logic Start-up FAULT Timer C F Missing Pulse V MIN Detect Clock Generator 50 k + SENSE1 SCLK Serial Port 100 mV (typ.) Interface SDA 50 k + SENSE2 GND 100 mV (typ.) Note: OTF condition applies for the TC655 device only. DS21734A-page 2 2002 Microchip Technology Inc.