Nvidia Jetson TX2 NX User Manual

Power
NVIDIA Jetson TX2 NX DG-10141-001_v1.1 | 13
POWER_EN
 POWER_EN is a level active signal. When high, the system powers on or stays on. When low,
the system powers down or stays off.
 The DevKit carrier board designs latch
POWER_EN state to ensure that the signal stays
active. The Jetson Nano DevKit carrier board uses an SR latch with discrete logic
components was implemented to latch the
POWER_EN signal and prevent it from being
affected by any other signal other than
SHUTDOWN_REQ*. The Jetson Xavier NX DevKit uses
a button MCU controller to latch the
POWER_EN signal. POWER_EN only goes low when a
shutdown sequence has been initiated.
SYS_RESET*

SYS_RESET* is bidirectional. The signal is controlled by the PMIC during power-on and
power-off. When the system is powered on,
SYS_RESET* can be driven by the carrier board
to reset the module. This results in a full system power cycle.
 The
SYS_RESET* signal is asserted by the PMIC during power-on.

SYS_RESET* is not asserted externally during the power-down sequence. When POWER_EN is
de-asserted, the PMIC performs a power down sequence that includes asserting
SYS_RESET*.
SHUTDOWN_REQ*

SHUTDOWN_REQ* is driven active (low) by the module if the system must be shut down, due
to a low power level, a thermal event, or by a GPIO on the PMIC that can be asserted under
software control to request a shutdown. The power control logic on the carrier board must
drive
POWER_EN inactive (low) if SHUTDOWN_REQ* is asserted.

SHUTDOWN_REQ* is not driven during power-on. It is pulled up to the 5V supply, so stays
inactive. If the system is on and reset is driven low, the PMIC will initiate a full power cycle
and start the power-on sequence. Again,
SHUTDOWN_REQ* is not asserted. SHUTDOWN_REQ*
will only go low when the system needs to shut down.

SHUTDOWN_REQ* is de-asserted after POWER_EN goes low. SHUTDOWN_REQ* comes from a
latch on module and is cleared when
POWER_EN goes low.
 If
SHUTDOWN_REQ is asserted, the PMIC will start a system shutdown. POWER_EN must be
de-asserted within 10 uS after
SHUTDOWN_REQ is asserted. The system will be powered off
(or nearly so) in that time.
Asserting
SHUTDOWN_REQ* is the recommended signal to initiate a power off. Just setting
POWER_EN high to power the system ON and low to power the system OFF can have issues.
Without the SHUTDOWN_REQ* signal, there can be a logic mismatch between the module and
carrier board. If the module shuts down due to a thermal issue, and so on, then without the
SHUTDOWN_REQ* signal the carrier board would not “know” that the module has shut down and
the carrier board may just keep
POWER_EN high. This can cause issues including uncertainties
for subsequent power on attempts. The correct sequence should be to assert
SHUTDOWN_REQ*
signal so that carrier knows that module is shutting down so the
POWER_EN signal can be
brought down as well. Using
POWER_EN to power the system OFF is an option, but
SHUTDOWN_REQ* must be asserted soon after.

Nvidia Jetson TX2 NX Specifications

General

Brand	Nvidia
Model	Jetson TX2 NX
Category	Computer Hardware
Language	English