People often take it for granted to power the circuit of the PCB, not knowing that this can cause damage and damage or non-destructive latch conditions. These problems may not be prominent until the start of mass production, when the tolerance of the device and design is tested, but it is too late, the project and product time and delivery will be greatly affected, and the cost will be greatly increased. To address the errors found during this phase, a number of modifications will be required, including PCB layout changes, design changes, and additional anomalies.
    With the advent of the integrated circuit era, many functional modules are integrated into one IC, so it is necessary to use multiple power supplies to power these modules. The voltages of these sources are sometimes the same, but more often they are different. The increasing number of system-on-chip (SoC) ics on the market has created a need for sequential control and management of power supplies.
    Analog Devices' data books usually provide enough information to guide design engineers in designing the correct power-on sequence for each IC. However, some ics explicitly require that an appropriate power-on sequence be defined. This is true for many of Analog Devices' ics. This requirement is common in ics that use multiple power supplies, such as converters (including ADC and DAC), digital signal processors (DSPS), audio/video, RF, and many other mixed-signal ics. Essentially, ics that contain some kind of analog input/output with a digital engine fall into this category and may require specific power timing control. These ics may have separate analog and digital power supplies, and some even have digital input/output power supplies, see the specific examples discussed below for details.
    This application note discusses some of the more subtle power supply issues that design engineers must consider in a new design, especially when the IC requires multiple different power supplies. At present, some of the more commonly used power supply voltages are: +1.8V, +2.0V, +2.5V, +3.3V, +5V, +12V, and −12V.

PULSAR ADC example - Absolute maximum rating
    All Analog Devices data books contain an Absolute Maximum Rating (AMR) section, which describes the maximum voltage, current, or temperature that can be applied to the pin or device to avoid causing damage.
    The AD7654PulSAR 16-bit ADC is an example of a mixed-signal ADC with three (or more) independent power supplies. These ADCs require a digital power supply (DVDD), analog power supply (AVDD), and digital input/output power supply (OVDD). They are ADCs that convert analog signals into digital code, so an analog core is required to process the incoming analog input. The digital kernel handles the bit determination process and control logic. The I/O kernel is used to set the level of the digital output for interface with the host logic (level conversion). The power supply specifications for the ADC can be found in the "Absolute Maximum Rating" section of the corresponding data sheet. Table 1 is taken from the "Absolute Maximum Ratings" section of the AD7654 (Rev.B) data book.

Example of type Σ-Δ ADC

    AD7794 type Σ-Δ 24-bit ADC is another good example. Table 3 is taken from the "Absolute Maximum Ratings" section of the AD7794 (Rev.D) data book.