Re: [Gumstix-users] Power down switch design

[Bruce F. <bfortnam@GlobalLocate.com>]

=20
On 10/13/06, Dave Hylands wrote:

> I stumbled across this today, and since this particular topic came up
recently on the list, I figured it was worth posting.

> The article is titled:
> SPST pushbutton switch combines power-control, user-input functions

> HTML version of the article:

>
<http://www.edn.com/article/CA6372827.html?spacedesc=3Ddesignideas&indust=
r
yid=3D44217>

> PDF version of the article:
> <http://www.edn.com/contents/images/6372827.pdf>

> In order to be useful, it would require some changes in u-boot (in
order to assert the P1.1 (aka Power Hold) signal,
> although this could also be done using bootcmd commands as well.

The LTC2954 from Linear Tech performs essentially the same function
without requiring the Power Hold signal from the CPU:
http://www.linear.com/pc/productDetail.do?navId=3DH0,C1,C1003,C1144,C1129=
,
P27972

Once it turns on, it stays on until it gets a kill signal from the CPU
or you hold the button down for a long time.

--Bruce