User's Manual

Telit GE863-QUAD / GE863-PY
Hardware User guide
1vv0300697, Rev. ISSUE#0, - 21/11/05
Reproduction forbidden without Telit Communication written authorization – All Right reserved – Right of modification reserved page 25 of 70
NOTE: The UART input line TXD (rx_uart) of the GE863-QUAD is NOT internally pulled up with a
resistor, so there may be the need to place an external 47KΩ pull-up resistor, either the DTR
(dtr_uart) and RTS (rts_uart) input lines are not pulled up internally, so an external pull-up resistor
of 47KΩ may be required.
A power source of the internal interface voltage corresponding to the 2.8VCMOS high level is
available at the VAUX pad, whose absolute maximum output current is 100mA.
Pull-up resistors can be connected to the VAUX pad provided that the pulled-up lines are
GE863-QUAD input lines connected to open collector outputs in order to avoid latch-up
problems on the GE863-QUAD.
Care must be taken to avoid latch-up on the GE863-QUAD and the use of this output line to
power electronic devices shall be considered with care, especially for devices that generate
spikes and noise such as level translators, digital ICs or microcontroller, failure in any of these
condition can severely compromise the GE863-QUAD functionality.
NOTE: The input lines working at 2.8VCMOS can be pulled-up with 47KΩ resistors that can be
connected directly to the VAUX line.
NO disturbing devices should be powered with the VAUX line, otherwise the module functionality
may be compromised.