TC655 Datasheet | Microchip Technology

Features : - Temperature Proportional Fan Speed for Reduced Acoustic Noise and Longer Fan Life - Fan Sense™ Protects against Fan Failure and Eliminates the Need for 3-wire Fans - Overtemperature Detection (TC655) - Efficient PWM Fan Drive - Provides RPM Data - 2-Wire SMBus™-patible 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: -40°C to +85ºC Applications: - Personal puters and Servers - LCD Projectors - Data and Tele Equipment - Fan Trays - File Servers - Workstations - General Purpose Fan Speed Control Package Type 10-Pin MSOP VIN 1 CF 2 SCLK 3 SDA 4 GND 5 TC654 TC655 10 VDD 9 VOUT 8 SENSE1 7 SENSE2 6 FAULT Description : The TC654 and TC655 are PWM mode fan speed controllers with Fan Sense technology for use with brushless DC fans. These devices implement temperature proportional fan speed control which lowers acoustic fan noise and increases fan life. The voltage at VIN (Pin 1) represents temperature and is typically provided by an external thermistor or voltage output temperature sensor. The PWM output (VOUT) is adjusted between 30% and 100%, based on the voltage at VIN. The PWM duty cycle can also be programmed via SMBus to allow fan speed control without the need for an external thermistor. If VIN is not connected, the TC654/TC655 will start driving the fan at a default duty cycle of 39.33%. See Section 4.3 “Fan Start-up” for more details. In normal fan operation, pulse trains are present at SENSE1 (Pin 8) and SENSE2 (Pin 7). The TC654/ TC655 use these pulses to calculate the fan revolutions per minute (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/TC655 to assert a logic low alert signal (FAULT). The default threshold value is 500 RPM. Also, if this condition occurs, F1F (bit 0<0>) or F2F (bit 1<0>) in the...