User's Guide

UL865 Hardware User Guide
1VV0301050 Rev 2 – 2013-10-09
To unconditionally reboot the UL865, the pad RESET* must be tied low for at least 200
milliseconds and then released.
The maximum current that can be drained from the ON* pad is 0,15 mA.
WARNING:
The hardware unconditional Restart must not be used during normal operation of the
device since it does not detach the device from the network. It shall be kept as an
emergency exit procedure to be done in the rare case that the device gets stuck waiting for
some network or SIM responses.
NOTE:
Do not use any pull up resistor on the RESET* line nor any totem pole digital output.
Using pull up resistor may bring to latch up problems on the UL865 power regulator and
improper functioning of the module.
The line RESET* must be connected only in open collector configuration; the transistor
must be connected as close as possible to the RESET* pin.
TIP:
The unconditional hardware restart must always be implemented on the boards and the
software must use it as an emergency exit procedure.
A simple circuit to do it is: