24 Nov
2004
24 Nov
'04
3:53 a.m.
From: "John Honniball"
<coredump(a)gifford.co.uk>
Jules Richardson wrote:
Hi
Although, not particularly good practice, as long as the
power dissipation is kept down, this is a design within specifications
of the part. They have built in current limit and are suppose
to be able to handle continuous loads in current limit.
This means that they can be paralleled.
I once talked with some application engineers at National
about this type of operation.
Dwight
In the six or so Atoms that have passed through
my hands though I've
never had one with the original supply, so I can't confirm that :) (All
of mine have either been kits - and I assume the PSU was optional - or
previous owners have bypassed the regulators and used a more capable
supply)
Ah, that was a standard modification. The Atom uses two 7805
regulators in parallel, which is not a good way to turn two
1A regulators into a 2A PSU. In practice, one regulator
(depending on the voltage tolerances of the parts) takes
nearly all the load, while the other regulator just sits
there. So, many Atom users who expanded their machines
also bypassed the regulators and added a proper external
supply.
I'll check my boxed Atom in the loft sometime to see what
brick it's got.