10.3 What To Do and What Not To Do

• Do partition the analog, digital, and power-supply circuitry into separate sections on the PCB.
• Do use a single ground plane for analog and digital grounds.
• Do place the analog components close to the ADC pins using short, direct connections.
• Do keep the SCLK pin free of glitches and noise.
• Do verify that the analog input voltages are within the specified PGA input voltage range under all input conditions.
• Do float unused analog input pins to minimize input leakage current on all other analog inputs. Connecting unused pins to AVDD is the next best option.
• Do provide current limiting to the analog inputs in case overvoltage faults occur.
• Do use a low-dropout linear regulator (LDO) to reduce ripple voltage generated by switch-mode power supplies. Reducing ripple is especially important for AVDD where the supply noise can affect the performance.
• Don't cross analog and digital signals.
• Don't allow the analog and digital power supply voltages to exceed 5.5 V under any condition, including during power-up and power-down.

Figure 100 shows the do's and don'ts of the ADC circuit connections.

Figure 100. Do's and Don'ts Circuit Connections