User Guide

Table Of Contents
LE910Cx HW User Guide
1VV0301298 Rev. 34 Page 47 of 131
Not Subject to NDA
Figure 11: Power down timing using HW_SHUTDOWN_N
Note
: Recommended values are as follows: R2 = 47k, R1 = 10k.
Note
: Do not use any pull-up resistor on the HW_SHUTDOWN_N line
or any totem pole digital output. Using a pull-up resistor may cause
latch-up problems on the LE910Cx power regulator and improper
functioning of the module.
The HW_SHUTDOWN_N line must be
connected only in an open-collector configuration.
Note
:
The Unconditional Hardware Shutdown must always be
implemented on the boards, but this function must use it only as an
emergency exit procedure, and not as a normal power-off operation.
Powering OFF the Module
Powering OFF the module should be done gracefully allowing the module to complete all
ongoing and pending tasks while properly handling all memory buffers.
In a complete power supply shut down is needed, the below procedure must be followed:
1. Perform a HW shutdown as described in Section 5.3.1
2. Wait for the HW Shutdown procedure to complete (monitor the PWRMON/SW_RDY
pin).
3. Turn OFF power supply to the module
200
mS Sec < T_Hold
VBATT
SHDN_N
SW_RDY
T_RDY ~0 Sec
V_AUX
PWRMON
T_PWRMON ~0 Sec
OFF State
Active State