User's Manual

LE910 V2 HARDWARE USER GUIDE 1VV0301200 Rev.2 Preliminary • 2015-08-04 31 of 81
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5.2 Power on
To turn on the LE910 V2 the pad ON_OFF* must be tied low for at least 5 seconds and then released.
The maximum current that can be drained from the ON_OFF* pad is 0,1 mA.
A simple circuit to do it is:
NOTE:
Don't use any pull up resistor on the ON_OFF* line, it is internally pulled up. Using pull
up resistor may bring to latch up problems on the LE910 V2 power regulator and improper
power on/off of the module. The line ON_OFF* must be connected only in open collector
or open drain configuration.
In this document all the lines that are inverted, hence have active low signals are labelled
with a name that ends with”#",”*” or with a bar over the name.
To check if the device has powered on, the hardware line PWRMON should be monitored.
It is mandatory to avoid sending data to the serial ports during the first 200ms of the
module start-up.