[time-nuts] FE-5680A Breakout board

gonzo . cadbloke at hotmail.com
Sat Jan 14 19:56:05 EST 2012


Hi Attila,
thanks for your comments.

On the schematic the inputs are listed as "supply" (ie. "+15V_SUPPLY" and "+5V_SUPPLY"), where as the outputs of the regs are marked with their actual voltages.
The boards silk screen on the other hand lists the inputs as 7V and 17V. 

In my original post I said I'd used the LM317 from the Eagle library, but infact use the pin compatible LM1084 (Eagle doesn't know about the LM1084).
The LM1084 is a 5A device (vs 1.5A:LM317) with 1.5V LDO (vs 2.5V:LM317), so 17V is an acceptable minimum input.

Heatsinking of the LM/TS/AMS1117 is not generious and it does run hot when SJ1 is shorted and the board is running with a single supply (15V input to the 5VReg).
I have added more heatsink ares to the V1.1 board, but the '1117is rated to 800mA and is only loaded to 10% so I don't think it is a problem.

It is worth remembering that the boards I'm offering are simply the left overs from my own use (V1.0 board at least)  and was never intended to be fully idiot proof. Fortunatly, this list seems to be an idiot free corner of the internet


> Date: Sat, 14 Jan 2012 16:21:57 +0100
> From: Attila Kinali <attila at kinali.ch>
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Subject: Re: [time-nuts] FE-5680A Breakout board
> Message-ID: <20120114162157.408e651b.attila at kinali.ch>
> Content-Type: text/plain; charset=US-ASCII
> 
> On Fri, 13 Jan 2012 09:59:03 +0000
> "gonzo ." <cadbloke at hotmail.com> wrote:
> 
> > yes, I'm certainly getting the boards made where production is cheap.
> > Other things seem to be cheap there too; like used Rb Osc!
> > 
> > I'm paying just under $3 per board (double sided, plated through, solder mask both sides, silk screen both sides).
> > If it wasn't for that, I wouldn't be able to sell them for $10 with components.
> [...] 
> > I've sent you the CAD files so you can have a play.
> 
> 
> Thanks a lot! I had a look at the files... The lowest i get is
> eurocircuits with apporx 9EUR/pce @ 10 pieces and 5.5EUR/pce @ 20.
> There is no way i can match your price at these low batch sizes.
> Much less with the parts too...
> 
> 
> BTW: How hot does IC2, the TS1117 run? It seems to have an awfully small
> cooling copper area.
> 
> BTW2: Your board is marked as 15V input voltage. But the LM137 needs
> >2V voltage difference at these currents. Ie it needs at least 17V if
> not 18V input voltage.
> 
> 			Attila Kinali
> 
> 
> -- 

 		 	   		  


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