The ADS5400-SP uses three power supplies. For the analog portion of the design, a 5-V and 3.3-V supply (AVDD5 and AVDD3) are used, while the digital portion uses a 3.3-V supply (DVDD3). The use of low-noise power supplies with adequate decoupling is recommended. Linear supplies are preferred to switched supplies; switched supplies generate more noise components that can be coupled to the ADS5400-SP. The PSRR value and the plot shown in Figure 41 were obtained without bulk supply decoupling capacitors. When bulk (0.1 μF) decoupling capacitors are used, the board-level PSRR is much higher than the stated value for the ADC. The power consumption of the device does not change substantially over clock rate or input frequency as a result of the architecture and process.

Figure 41. PSRR versus Supply Injected Frequency