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ADS1230 and 8052

ajith kumar
Intellectual 320 points

Dear Bob,

 As per your information i provided enough ground plane for analog and digital ground ,and in the analog section , includes the necessary connections including filtering capacitors and inductors.I used the filling plane technique in "Express pcb"(double sided) to place the ground plane.So near the connection to analog input the ground plane is filled on both sides of  each track.So should i remove those ground plane from the sides of the track near analog input.Or it is good to place the analog ground near the analog input.Is there any chance to affect noise towards sensitive analog inputs from ground plane.

 Also after the final verification of the board i observed that the microcontroller's crystal is almost near(1 cm)to ADC ic,is there any chance of affecting noise from crystal to the device.Expecting your valuable suggestion....

                                                    Thank you 

                                                      by Ajit..

  • 0
    TI__Guru** 113765 points

    Ajtih,

    The ground can help you and can hurt you as you have already mentioned.  It is very difficult to say for your situation.  Most usually it is helpful to have ground fill around the traces.  Just keep in mind that two conductors with a small space between them is a capacitor.  Also remember that a ground plane is not just an area where void area is filled with copper.  A good ground plane is one that has little or no disturbance within it.  The reason for a ground plane as opposed to just a ground fill is that return current likes to flow directly under the trace in which the current originated at these lower frequencies.  When this is disturbed there can be noise.

    Also remember that any time current flows through a trace there is field produced.  Clock signals can emit enough signal radiation to affect other circuits around them.  The more current, the larger the radiated field.  Here again, ground fill can help absorb some of the radiation.  As far as your micro crystal, it is probably good to have a ground ring around the crystal if there is minimal separation to the ADC.

    Best regards,

    Bob B