ADS1261: ADS1261 in single-ended application

Hi Takuchi,

There is not much to review here, but it looks pretty good

• You have a mid-supply (DVDD) voltage on the START pin. I don't know why you would do this, I would think you either want this pin pulled up or pulled down through a 10k or greater resistor since it seems like you are controlling this pin with your MCU
• I don't see any ground connections (vias) on some of your supply decoupling and filter capacitors. Maybe you will add those later?
• If you want to measure single-ended signals with the ADS1261, you must bypass the PGA. I just want to make sure this is clear
• I don't see a noise specification for your linear regulator, you might consider a better LDO. We typically use the TPS7A4700 on our designs because it is low noise and has an adjustable output, but can use a similar device with a fixed output if you want
• The resistor on AVDD (R32) will cause a voltage drop between the regulator output and the AVDD pin. In most cases, this voltage will be negligible, but there are certain circumstances where the ADC draws a lot of current for short periods of time (instantaneous current), which could cause significant voltage drop. This effect is usually most apparent at power up. There is nothing wrong with adding that resistor, but you should keep this in mind during your prototyping if you start seeing the ADC resetting or brown out conditions
• The voltage rating on C61 (6.3V) is not very high compared to the supply voltage (5V). This could reduce the capacitance over time and temperature, especially for an X5R cap. I would consider finding a capacitor with a higher voltage rating

-Bryan