Embedian, Inc.
148
SMARC-FiMX6 Computer on Module User’s Manual v.1.2
current RTC voltage rail.
SMARC-FiMX6
operating and standby power
comes from the single set of
VDD_IN
pins. This suits battery power sources
well, and is also easy to use with non-battery sources.
4.1.3. RTC/Backup Voltage
RTC backup power is brought in on the
VDD_RTC
rail. The RTC
consumption is typically 15 microA or less. The allowable
VDD_RTC
voltage
range shall be 2.0V to 3.25V. The
VDD_RTC
rail is sourced from a Carrier
based Lithium cell, or it may be left open if the RTC backup functions are not
required.
SMARC-FiMX6
module is able to boot without a
VDD_RTC
voltage
source.
Lithium cells, if used on Carrier, shall be protected against charging by a
Carrier Schottky diode. The diode is placed in series with the positive battery
terminal. The diode anode is on the battery side, and the cathode on the
Module
VDD_RTC
side.
Note that if a Super cap is used, current may flow out of the Module
VDD_RTC
rail to charge the Super Cap.
4.1.4. Power Sequencing
The Module signal
CARRIER_PWR_ON
exists to ensure that the Module is
powered before the main body of Carrier circuits (those outside the power
and power control path on the Carrier). The main body of Carrier board
circuits should not be powered until the Module asserts the
CARRIER_PWR_ON
signal as a high. Module hardware will assert
CARRIER_PWR_ON
when all Module supplies necessary for Module
booting are up.
The IO power of carrier board will be turn on at the stage of power on
sequence. If the IO power of carrier board been turn on earlier than the
SMARC
module, the power on carrier board might feedback to
SMARC
module through IO lines and disturbs the
SMARC
module power on
sequence. More seriously, it might cause to the CPU won’t boot up. It is
always recommended that the power on module has to be earlier than that
on carrier board.
The boot up of module depends on when you release the reset signal of
your carrier board. The module will boot up when the reset signal on your
carrier board is released. Before that, the module will not boot up. That’s