Sender: <marv@lancaironline.net>
To: lml@lancaironline.net
Date: Sun, 29 Apr 2007 13:30:41 -0400
Message-ID: <redirect-2016362@logan.com>
Received-SPF: none
 receiver=logan.com; client-ip=69.36.178.59; envelope-from=hwasti@starband.net
From: "Hamid A. Wasti" <hwasti@starband.net>
User-Agent: Thunderbird 1.5.0.10 (Windows/20070221)
MIME-Version: 1.0
Subject: Re: [LML] 12v supply to stabilize avionics
References: <list-2016295@logan.com>
In-Reply-To: <list-2016295@logan.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

Bob,

I am quite familiar with that particular chip.  All I can tell you is 
that you should get the design and try it and then decide. 

Linear Tech is a good company, I have a long history and an excellent 
relationship with them. I almost exclusively use their DC-DC converter 
chips.  Al that said, LTC, like all other companies in the industry 
plays games with specmanship to highlight their product and stand out 
from the crowd.  You can achieve their stated results under a very 
specific set of conditions, which I guarantee you will not exist in your 
real life implementation. A lot of the power loss equations have square 
terms in them.  Therefore, as you increase the output power, the power 
loss increases disproportionately.  As I said in my last post, I do not 
want to deliver a lecture on power supply design; most people are not 
interested and I am too busy designing one to have time for it.

The 0.1lbs weight is for the 5A reference design, with no enclosure and 
no heat sink.

Bottom line: Get the parts you think will give you this performance.  
Acquire the equipment to actually be able to test it.  Then test it in 
real life and report back what you find.

Regards,

Hamid

bob mackey wrote:
> Several asked for specs, so here they are...
>
> As some surmised, this is lighter weight than
> a second battery -- 0.1 lbs plus wiring.
> It uses an Linear LTC3780.
> http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1042,C1116,P10090
>
> The spec sheet for the 12V supply is attached.
>
> -bob mackey
>