LM940 Hardware Design Guide
1VV0301352 Rev. 18
Page 38 of 75
2022-01-04
Not Subject to NDA
Figure 7: Fast Shutdown by GPIO
The DTE should monitor the status of Shutdown Indicator to proceed fast power-off.
Note: VBATT must not be removed before Shutdown Indicator goes
LOW.
Warning: Not following the recommended shut-down procedures
might damage the device and consequently void the warranty.
6.3.3.
Unconditional Shutdown (Support Only on LM940 2.0)
LM940 2.0 support unconditional hardware shutdown.
To turn off the module, SYSTEM_RESET_N pad must be asserted low more than 1
seconds and then it should be kept low.
When the SYSTEM_RESET_N is asserted low more than 1 second, the LM940 enters
finalization state and after the end of the shutdown process Shutdown Indicator will go to
low.
Usually, it takes the LM940 less than
100
milliseconds from asserting SYSTEM_RESET_N
until reaching a complete shutdown. The DTE should monitor the status of Shutdown
Indicator to observe the actual power-off.
Note: To completely shut down the LM940 module, the
SYSTEM_RESET_N pin must be asserted and kept low.
Otherwise, the LM940 will turn on again after shut down.
