Driver IC Replaces All Cooling Fan Components

A reduction in a traditional cooling fan’s component count from eight to one is made possible by the US79 single IC fan driver- a fan is an essential part of a CPU: if it fails, the CPU often does, too. The US79 provides exceptional reliability by simplifying fan assembly design and adding critical protection circuitry. The 3-lead IC also eliminates 13 solder joints as a potential source of fan reliability problems (the photo shows the chip connected to a motor’s windings).In addition, the US79 IC provides built-in protection against all environmental causes of fan failure. These include overheating, reverse voltage, RFI suppression, power supply overvoltage, inductive spikes caused by the output transistor clamp, and locked-rotor protection. Use of the US79 raises a fan’s ESD tolerance from 3 kV to 25 kV and from 3 kV to 9 kV at the IC’s pins. This was accomplished by eliminating the IC’s power supply pin. Power is supplied through the motor coils, which filter ESD nicely. The device also offers a low starting voltage of 2.2V for 3V computers, low power dissipation, N-channel MOS output transistors for low V_sat, elimination of “dead angle” effects, and a 40-to-400-mA driver capability. It comes in a standard 3-pin UA package. Samples are available now.