User Guide

LE910Cx HW User Guide
1VV0301298 Rev. 34 Page 50 of 131
Not Subject to NDA
Figure 13: Example of Timing diagram for Fast Shut Down
The most important thing is that a system should give enough energy. The LE910Cx turns
off safely for 30ms after the Fast Shut Down is triggered. Otherwise, unwanted memory
corruption may occur. The VAUX pin can be used to check if the LE910Cx is turned off. If
VUAX is low, LE910Cx is turned off.
The following formula can be used to calculate Ctank value to provide the LE910Cx with
sufficient energy during the Fast Shut Down.
The LE910Cx consumes up to 800mA and 30ms is the typical time to perform shutdown
and 1V is the minimum voltage margin from the threshold of LE910Cx hardware reset.
Based on the formula, more than 24mF is needed for the Fast Shut Down.
But the Ctank value should be optimized depending on the detection voltage and load
current LE910Cx consumes in the customer’s system.
Note:
Make the same plot during system verification to check timing
and voltage levels.