Verdin Carrier Board Design Guide
Preliminary
– Subject to Change
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3.3.6
“Running” to “Module OFF” (shutdown)
Figure 53: “Running” to “Module OFF” (shutdown) Power Sequence
The regular shutdown sequence is initiated by the operating system. A short pressing on the power
button (CTRL_PWR_BTN_MICO#) will generate an interrupt. However, the operating system is
responsible for reacting to this interrupt and initiating shutdown. Depending on system
requirements, the OS may directly initiate the shutdown process, may display power options or not
react at all to power button interrupts.
The operating system makes sure that everything is put to a state in which a shutdown sequence
can be performed without corrupting the system. This could be for example saving temporary data,
flushing buffers, closing files or disconnecting services. After all processes are stopped, the last task
of the operating system is to request a shut down from the PMIC.
The PMIC is first asserting the SoC reset as well as the CTRL_RESET_MOCI#. It then removes the
different voltage rails in the required order. This also includes disabling the CTRL_PWR_EN_MOCI
signal. The carrier board needs to turn off the power rails after the CTRL_PWR_EN_MOCI signal is
disabled.
After all the rails have been removed, the main module input rail VCC remains. The
CTRL_FORCE_OFF_MOCI# remains high for certain amount of time. On some modules, it takes
several seconds until the CTRL_FORCE_OFF_MOCI# goes low. If the carrier board ignores the
CTRL_FORCE_OFF_MOCI# signals and does not implement the kill feature, VCC will remain
applied to the module and the system will remain in the “Module OFF” state.
VCC_BACKUP
VCC
Early Module Rails
PWR_1V8_MOCI#
Carrier Board rails
Later Module Rails
Module Peripherals
CB Sleep Peripherals
CTRL_PWR_BTN_MICO#
CTRL_RESET_MICO#
CTRL_PWR_EN_MOCI
CTRL_SLEEP_MOCI#
CTRL_FORCE_OFF_MOCI#
CTRL_WAKE1_MICO#
SoC RESET
CTRL_RESET_MOCI#