Embedian, Inc.
39
SMARC-iMX8MM Computer on Module User’s Manual
v. 1.2
USB[0:3]_EN_OC#
pins
may
be
left
unused,
or
they
may
be
used
as
USB[0:3]
power
enables,
without
making
use
of
the
over
‐
current
detect
Module
input
feature.
The
SMARC
‐
iMX8MM
Module
USB
power
enable
and
over
current
indication
logic
implementation
is
shown
in
the
following
block
diagram.
There
are
10k
pull
‐
up
resistors
on
the
Module
on
the
SMARC
USB[0:3]_EN_OC#
lines.
Outputs
driving
the
USBx_EN_OC#
lines
are
open
‐
drain.
The
Carrier
board
USB
power
switch,
if
present,
is
enabled
by
USB[0:3]_EN_OC#
after
a
device
connection
is
detected
on
the
DP/DM
lines.
The
Enable
pin
on
the
Carrier
board
USB
power
switch
must
be
active
high
and
the
Over
‐
Current
pin
(
OC#
)
must
be
open
drain,
active
low
(these
are
commonly
available).
No
pull
‐
up
is
required
on
the
USB
power
switch
Enable
or
OC#
line
on
carrier
board;
they
are
tied
together
on
the
Carrier
and
fed
to
the
Module
USB[0:3]_EN_OC#
pin.
Figure
4.
USB
Power
Distribution
Implementation
on
Carrier
