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→Sequencing
==Sequencing==
Implementing correct power-up sequence for DM8148 processor is not a trivial task beacuse several power rails are involved. Maya hides this complexity because it embeds most of the circuitry required. However some simple rules have to be followed to power it up properly.
In typical applications DM8148 processor interfaces directly to 3.3V-powered devices that are hosted on carrier board. In order to be compliant with DM8148 power-up requirements, these devices should be turned on at a specific time during power-up sequence. To achieve this, Naon provides EN_BCK2_LS signal. When maya is powered, this signal is low: this means that carrier board 3.3V-powered devices have to be powered off. During power-up sequence this signal shall be raised by Maya circuitry, indicating carrier board 3.3V-powered devices have to be turned on. After this rising edge, EN_BCK2_LS shall be kept high.
The following picture shows the power sequence of Maya SOM in the typical scenario. It is assumed that:
* carrier board implements power supply unit providing 3.3V power supply voltgage
