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> On Apr 10, 2013, at 2:51 PM, KPL wrote:
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> Hi, distributed brains.
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> Has anybody used microchip's TC652 fan controller? That seemed like a
> very simple/safe way to slow down fans of my PC, but somehow I can not
> get it to work as intended. Circuit is just like the one described in
> TC652 demo board users guide.
> Fan is running, but fan fault detection does not work at all, and
> temperature control seems very erratic.
> Circuit is very sensitive to my hand nearby it, even without touching it.
> 5V power comes from a cheap wall wart, which was good enough for all
> kinds of PIC circuits before. 12V for a fan comes from another wall
> wart.
> There is a big cap across the 5V power.
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> Unfortunately I have no scope available now.
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> Any ideas?
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> --
> KPL


More details please....

*Circuit is very sensitive to my hand*
What happens when you move your hand nearby ?
Perhaps the transistor is=20

How are you varying the temperature ?
How are you monitoring the temperature ?
how are you monitoring /FAULT ?
How are you driving /SHDN ?  It may be wise to put a pullup resistor to Vdd=
 on this pin.

Do you have a DMM ?
If so, check the voltage going to the TC652.
    Datasheet says chip can accept 2.8 to 5.5V.



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