User Guide

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10 Power management
The 96Boards specification defines how power arrives to the board and few supplies that the board needs to provide. The
on board power requirement for each 96Boards implementation depends on the SoC and the set of peripherals that are
specific to that implementation.
The DB8 uses three buck regulators,(carrierboard) U37, U38 and U35. U38 takes the power in to the board and generates
3.8V at 6A. This voltage serves as the power in voltage to the on-board PMI8996 IC. U37 takes the power in to the board
and generates 5V at 5A. This voltage feeds the USB HOST power limit switches, provides power to the Low Speed Expansion
port and other HW peripheral interfaces. U35 takes the power in to the board and generates 3.3V at 5A. 3.3V is used to
power HW peripherals as well as to expansion connectors.
10.1 DC Power Input
The 96Boards specification calls for a power to be provided to the board in one of the following ways:
●
An 8V to 18V power from a dedicated DC jack.
o The DB8 supports this requirement through the use of J23, ‘SYS_DCIN’ power connector. Please
note:

the SYS_DCIN can be as low as 6.5V on the DB8.
●
Note that the DB8 operates from a ~24W supply such as a 12V/2A supply. An 8V to 18V power from the SYS_DCIN pins
on the Low Speed Expansion Connector.
Please note: the SYS_DCIN can be as low as 6.5V on the DB8. The DB8
supports incoming power through this connector.
10.2 Power Source Selection
Following the information in section 9.1, the DB8 has only two sources for board incoming power. The 96Boards
specification calls for only one power source to be applied to the board at any given time. Following this requirement,
the user of the DB8 should never apply power to the board from J1 and the Low Speed Expansion connector at the
same time.There is no active or passive mechanism on the DB8 to prioritize one source over the other.
10.3 Power Consumption
TBD
10.4 Power Sequencing
Upon applying power to the DB8 (either one of the two sources), both buck regulators will be enabled and will start
regulating their target voltages. When the output of U38 is on, it will power the on-board PMIC, the PMI8996. PMI8996
generates VPH_PWR which supplies the PM8996. The sequencing of all power rails is set within the PMIC configuration