[OZAPRS] Power supply options

[Dave Ingram]

Andrew Rich wrote:
> Just got myself setup with a 13.8 40A Switchmode PSU.
> 
> I am keen to hear what backup power supply options people are running ?
> 
> I have a rather large SLA battery here.
> 
> I am trying to avoid a relay switched solution.

What about a couple of Infineon ProFet high side switches in parallel?
These
will switch 4-40V and carry 21A. 20mOhm on resistance and no moving parts.

The BTS442D2 from RS (354-5900) is $13.30 or from Farnell (743-367) is
$26.70.
I've used these on 12V for lower currents before and they operate nicely
with
a TTL input.

If you get in quick the BTS650P (in stock, but no longer brought in) is
good
for 70A and is only $21. Part number from Farnell is 1156451.

A supervisor circuit running of the 12V battery that draws low current (a
uP
that sleeps most of the time) could check the PSU supply voltage and if
that
had dropped, turn of that profet and activate the one from the battery.
Mind
you a relay that is held in by PSU volts that drops over to battery on
mains
failure would be much simpler, but I guess you have some reason for not
wanting to use a relay.


Regards,
	David.
-- 
David Ingram (VK4TDI)
Real email: dave at ingramtech dot com
Brisbane, Queensland, Australia
http://www.ingramtech.com/
MGRS: 56J MQ 991583    Maidenhead Grid Square: QG62lm
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