Forum Post: RE: ADS1247: Protection of inputs against IEC60255-27/IEC60950-1 Impulse Voltage tests

Hi Mikael, Thank you - it looks great. The main concern I have here is the inductor on pin 14, AVDD. There should not be any inductance on the power supply for this device family. I would expect that when the reference is turned on that the supply will droop due to the current surge required to charge the reference capacitor. As a rule of thumb, it's not a good idea to have an inductor or ferrite on the supplies or grounds of these devices. The PSRR of the device should be good enough so filtering of the power supply is not required, however if it's necessary it's better to use a resistor in series with the supply to form an RC filter. Keep the resistor relatively small (2-10ohms) to avoid issues.