LN920 HW Design Guide
1VV0301730 Rev. 1
Page 39 of 81
2021-08-11
Not Subject to NDA
6.3.1.
Graceful Shutdown
To safely power off the LN920 module, the host can use the graceful shutdown function.
To gracefully shutdown the LN920 module, FULL_CARD_POEWR_OFF# should be
asserted Low.
Once FULL_CARD_POWER_OFF# is asserted LOW, the LN920 module enters finalization
state, terminates active processes and prepare to turn off safely.
As shown in the diagram below,
Shutdown Indicator
*
pin
will indicate when the module
has completed turned off.
When the status transitions to Low, the module has completed shutdown procedure.
*
Shutdown Indicator (Boot OK) is optional function and is disabled by default.
The host can use the AT#SHDNIND command to assign one of the GPIOs as the Shutdown
Indicator pin. After enabling the function, the corresponding pin operates as a Shutdown
Indicator and also Boot OK function. About Boot OK, please refer to the Power On chapter.
Refer to the AT Reference guide document for more details about AT#SHDNIND.
6.3.2.
Fast Shutdown
For a quicker shutdown of the LN920 module, the host can use the fast shutdown
function.
If properly configured, one of GPIO lines can be used as Fast Shutdown
**
Trigger.
Once the Fast Shutdown Trigger senses a HIGH to LOW transition, fast shutdown is
triggered.
Then the LN920 module enters finalization state, it terminates active processes and
prepares to turn off safely. As shown in the diagram below, when the module is ready to
be turned off, it will be indicated via
Shutdown Indicator
*
.
