found some PWM Fan control chips

Daemonfly · Oct 3, 2002

http://www.microchip.com/1010/pline/analog/anicateg/thermal/dcfan/index.htm

Found these when searching the Microchip site for some PIC info. They look rather interesting. Heres the desc from the TC642"

The TC642 is a switch mode fan speed controller for use with brushless DC motors. Temperature proportional speed control is accomplished using pulse width modulation. A thermistor (or other voltage output temperature sensor) connected to the VIN input furnishes the required control voltage of 1.25Vto 2.65V (typical) for 0% to 100% PWM duty cycle. Minimum fan speed is set by a simple resistor divider on the VMIN input. An integrated Start-Up Timer ensures reliable motor start-up at turn-on, coming out of Shutdown Mode, or following a transient fault. A logic low applied to VMIN, pin 3, causes fan shutdown. The TC642 also features Microchip Technology's proprietary FanSense ™ technology for increasing system reliability. In normal fan operation, a pulse train is present at SENSE, pin 5, indicating normal operation. A missing-pulse detector monitors this pin during normal fan operation. A stalled, open, or unconnected fan causes the TC642 to trigger its start-up timer once. If the fault persists, the FAULT output goes low, and the device is latched in its Shutdown Mode. FAULT is also asserted if the PWM reaches 100%

I might have to consider these in some future projects

I figured I'd post the info for anyone else who might be interested.

drunkmonkey · Oct 5, 2002

ummm where do u buy em?

I WANT ONE!!!

d*mn mic402 chips cannot be found, but these sound cooler

Daemonfly · Oct 6, 2002

If I remember correctly, Mouser has them - probably Digikey too.

Since87 · Oct 6, 2002

Yes, Digikey does. They have a minimum order of $25 though.

The Digikey link is here.

Tecumseh · Oct 6, 2002

I didn't look at the design, but you will probably still need
a power transitor on the output. Look at the reference design.

Daemonfly · Oct 7, 2002

For heavy duty fan use, just add something like a IRL510 N-channel Mosfet or the IRL520N at 10A

Just posted the chip for anyone lookign to design their own system.

I'm going to build a full system controller with quite a few features using a 40mhz PIC, well, once I learn PIC microcontroller programming

found some PWM Fan control chips

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