MOTM

It depends on whether your circuit keeps analog and digital grounds 
separate.  If it does, then there is no reason to connect these on the 
board; they will be connected at the supply.  If the two grounds do 
connect at the board, it is not cause for concern.  I am running a 
couple of Veeblefetzer's off a MOTM-950, and the analog and digital 
grounds do connect together on the board.  I asked Paul S. if this would 
be a problem and he said no.

Richard Brewster
http://www.pugix.com

Adam Schabtach wrote:
> Ah, right you are. For some reason I got it into my head that the grounds
> would have to meet at the board, but you're right, the star point should
> stay back at the supply. Thanks.
>
> --Adam 
>
>   
>> -----Original Message-----
>> From: Mark [mailto:yahoogroups@...] 
>> Sent: Thursday, October 26, 2006 3:50 PM
>> To: Adam Schabtach; 'MOTM litserv'
>> Subject: Re: [motm] MOTM 6-pin power connector ettiquette question
>>
>>
>> If the header has a separate "digital" ground for the 5V 
>> source, then I don't see any reason to connect them on the 
>> PCB.  The "star point"
>> is at the power supply.  Many mixed-signal systems have 
>> analog and digital grounds separated in this way, with the 
>> ground pins of the AD and DA converters connected to the 
>> analog system ground.  Putting a ferrite bead or resistor 
>> between the grounds will create an impedance.
>>
>> On 10/26/06, Adam Schabtach put forth:
>>     
>>> Question for Paul, mostly, but maybe others have considered 
>>>       
>> the same thing:
>>     
>>> If I'm building a module from scratch, and I want it to play nicely 
>>> with my MOTM modules (present and future), and it's drawing 
>>>       
>> all three 
>>     
>>> voltages through a MOTM-standard 6-pin power connector, and it's a 
>>> hybrid analog/digital module, how do I connect together the digital 
>>> ground and the analog ground on my PC board? It may be 
>>>       
>> something of a 
>>     
>>> moot point because AFAICT my Power-One triple supply has the grounds 
>>> connected together anyway, but I'm wondering whether there is some 
>>> little nicety that I should observe, like maybe using a 
>>>       
>> ferrite bead instead of just plain copper.
>>     
>>> Thanks for any opinions or suggestions.
>>>       
>>  
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