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.comAdam 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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