piclist 2002\02\14\072047a >
Thread: TO-220 heatsinking
face BY : Trevor Page email (remove spam text)

Hi list,

I'm working on a home project (a drum machine based around a PIC!) that uses
a couple of 15V regulators in TO220 packages - a 7815 and 7915. They're both
providing about 200mA, and I'm expecting the total voltage drop across them
to be about 5V (15-0-15vrms transformer...), hence they'll both be
dissipating roughly 1W. According to the National Semi. datasheet and having
done some rough calculations myself I know that the device temperature will
be well within spec even if the device is used in free-air, i.e. without a
heatsink. However, I'm wondering if I should go back and redesign my (rather
dense) PCB before getting it printed, to allow space for a heatsink anyway.

My question is, can anyone suggest a reason why I *should* consider a
heatsink, especially if the device is switched on for very long periods of
time, i.e. days? Should I consider a much higher Ta in my calculations as
the air inside the enclosure warms up? There will be lots of space above the
regulator (within a 2u 19" rack).

Thanks in advance for any advice offered.



Trevor Page
Pace Micro Technology PLC
01274 538379

The E-mail and any attachments hereto are strictly confidential and intended
solely for the addressee. If you are not the intended addressee please
notify the sender by return and delete the message. You must not disclose,
forward or copy this E-mail or attachments to any third party without the
prior consent of the sender.

http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email @spam@listservspamBeGonespamspammitvma.mit.edu with SET PICList DIGEST in the body


See also: www.piclist.com/techref/index.htm?key=220+heatsinking
Reply You must be a member of the piclist mailing list (not only a www.piclist.com member) to post to the piclist. This form requires JavaScript and a browser/email client that can handle form mailto: posts.
Subject (change) TO-220 heatsinking

month overview.

new search...