The ADS5474 uses three power supplies. For the analog portion of the design, a 5V and 3.3V supply (AVDD5 and AVDD3) are used, while the digital portion uses a 3.3V supply (DVDD3). The use of low-noise power supplies with adequate decoupling is recommended. Linear supplies are preferred to switched supplies; switched supplies tend to generate more noise components that can be coupled to the ADS5474. The user may be able to supply power to the device with a less-than-ideal supply and still achieve good performance. It is not possible to make a single recommendation for every type of supply and level of decoupling for all systems. The power consumption of the ADS5474 does not change substantially over clock rate or input frequency as a result of the architecture and process.

Because there are two diodes connected in reverse between AVDD3 and DVDD3 internally, a power-up sequence is recommended. When there is a delay in power up between these two supplies, the one that lags could have current sinking through an internal diode before it powers up. The sink current can be large or small depending on the impedance of the external supply and could damage the device or affect the supply source.

The best power up sequence is one of the following options (regardless of when AVDD5 powers up):

1. Power up both AVDD3 and DVDD3 at the same time (best scenario), OR
2. Keep the voltage difference less than 0.8V between AVDD3 and DVDD3 during the power up (0.8V is not a hard specification - a smaller delta between supplies is safer).

If the above sequences are not practical then the sink current from the supply needs to be controlled or protection added externally. The max transient current (on the order of μs) for DVDD3 or AVDD3 pin is 500mA to avoid potential damage to the device or reduce its lifetime.

Values for analog and clock input given in the Section 5.1 are valid when the supplies are on. When the power supplies are off and the clock or analog inputs are still alive, the input voltage and current needs to be limited to avoid device damage. If the ADC supplies are off, the max/min continuous DC voltage is ±0.95V and max DC current is 20mA for each input pin (clock or analog), relative to ground.