"Jim Thompson" wrote in
message ...
On Thu, 12 May 2011 19:48:06 +0100, "Ian Field"
wrote:


"Sjouke Burry" wrote in message
...
Ian Field wrote:
Running at the full Vcc of 16V and the full frequency of 500kHz the 555
got so hot I had to add a clip-on heatsink.

Tried slowing it down to about 140kHz and the heatsink still gets
pretty
warm.

Is this normal?

Thanks.
Try again at a somewhat lower voltage, you may have exceeded
vcc for this particular unit and/or caused latching somewhere,
in which case almost the black magic smoke comes out.


Almost every datasheet I've seen says 16V - ISTR the Hitachi DS says 18V.


Perhaps a large capacitive load?


Been bench testing with no load (apart from driving the CR) and then with a
BC327/337 complementary emitter follower pair.