RE: Too hot 7805

[Don.F.Broadus@ucm.com]

The most common problem with heat in a 7805 regulator is to high of input
voltage. The minimum input for good regulation is 9 volts input (4 volt diff
in/out) if you run like 20 volt in 15 volts has to be dumped as heat. I also
recommend a small heatsink even with low current draw since I hate stuff
running hot. Looking at the front of the part left pin input (9 volts)
center ground /right pin output . 

> -----Original Message-----
> From:	Bruce Plecan [SMTP:nacelp@bright.net]
> Sent:	Thursday, January 27, 2000 10:22 PM
> To:	gmecm@diy-efi.org
> Subject:	Too hot 7805
> 
> I'm running a 7805, to supply 5v to a 2732, and 2 74LC 161s, all the load
> is
> a LED with a 1K inline resistor.
>    The 7805 is really hot after just seconds, I've checked my wiring a
> jillion times, ans still that way.
>   Can this 3 chips be drawing that much current?.
> Grumpy
>   This is for the ecm bench, and when "proven" will be ready for prime
> time
> (FTP).
> 
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