the TC647 and TC649 fan controllers

TelCom Semiconductor Inc. (Mountain View, CA) recently announced two new additions to their proprietary line of fan controllers: the TC647 and TC649. The TC647 and TC649 are stand alone, low-cost fan managers that integrate a pulse width modulation (PWM) fan speed controller with start up timer and fan fault detection circuitry. The fan speed control's PWM is claimed to reduce the acoustic noise of a fan, extends fan life, and lowers average fan operating current. The TC647/649 can drive any standard two-wire fan through a low cost transistor or logic level MOSFET. The devices take a temperature signal, generated with a NTC thermistor and resistor, as input. These fan controllers provide temperature proportional fan speed control, whereby the fan speed is increased linearly from 40 percent speed to 100 percent speed based on a user-programmed temperature range. The TC647 and TC649 differ from the TC642 and TC646 in one significant way, the TC647 and TC649 do not include an OTF (over temperature fault) alert. The TC647/649 are available in standard 8-pin PDIP and SOIC packages and are considered ideal for personal computer motherboards, power supplies, and any other application that uses brushless dc fans for forced-air cooling. Both package options are available with commercial and industrial temperature ranges. In quantities of 1,000, pricing for the TC647 starts at $1.40, and pricing for the TC649 starts at $1.33.