● GND layout
In other companies' ADC documentation, the system GND layout procedure was explained as follows.
(1) Place ADC on the AGND plane.
Connect the AGND pin and DGND pin of the ADC with a low impedance GND plane.
(2) Place the MCU and other digital ICs on the DGND plane.
(3) The connection point between the AGND plane and DGND plane should be between the ADC and MCU, or near the power supply circuit.
In your company, which is the recommended connection point for GND?
In the ADS1247 data sheet (figure123), the GND plane connection point is between the ADC and MCU. It is not near the power supply circuit (Supply Generation).
● VDD circuit design
In other companies' materials, the procedure of system power supply circuit design was explained as follows.
What are your views on these points?
(1)Analog power supply
Prepare a dedicated power supply for the ADC power supply (AVDD pin, DVDD pin).
Separated by ferrite beads between AVDD pin and DVDD pin of ADC. ‥
(2) Digital power supply
Prepare a dedicated power supply for MCU and other digital ICs
Can separating the AVDD and DVDD pins with a ferrite bead improve the performance of the ADS1247?
How about an R-C filter instead of ferrite beads?
●About separation of analog power supply and digital power supply
Regarding to separation of analog power supply and digital power supply,
If each of power uses a dedicated power supply, this will increases costs.
Therefore, I am considering the following power supply in my design as below.
5V LDO → Digital circuit (power supply for digital circuit only)
↓
→R-C filter →Analog circuit (power supply for analog circuit)
R: about 10ohm
What do you think about this?
Could you enlarge upon your suggestion?
