System Power-Up Sequence; Rtc Power And Coin Cell Charger - Digi ConnectCore 8X Hardware Reference Manual

The ConnectCore 8X System-on-module

System power-up sequence

When the power supply is connected to the ConnectCore 8X module, the PMIC and the MCA are the
first components to be powered up. VSYS and VSYS2 are PMIC supplies, while VCC_MCA is the Micro
Controller Assist input power line. The system power-up sequence is as follows:
1. The MCA starts to run as soon as it is powered up. After a certain programmable time, it will
release the PWRON line of the PMIC (PMIC power on/off).
2. Once the PMIC is switched on, it starts an initialization process as determined by its OTPs.
Finally the CPU reset line, which is controlled by both the PMIC and the MCA, is released.
The following time diagram shows the power-up sequence.

RTC power and coin cell charger

The VCC_LICELL pin supports coin cell charger functionality. This pin is also the input power supply for
an always-on regulator of the PMIC (VSNVS) that feeds the low-power mode circuitry of the CPU. In
the ConnectCore 8X module, the low-power modes of the system (RTC) are supported by the on-
module MCA, not by the i.MX 8X CPU. Therefore, in order to reduce the static power consumption of
the SoM, do not power the VSNVS regulator in low power mode. The coin cell should only power the
VCC_MCA power domain through the diode configuration as shown in the following diagrams.
If the coin-cell charger functionality is mandatory, place a reverse diode between VCC_LICELL and the
coin cell.
ConnectCore® 8X System-on-Module Hardware Reference Manual
Power interfaces
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