Telit Wireless Solutions GE863-QUAD - Manual (Page 29)

GE863-QUAD
GE863-PY
1vv0300715 Rev. 1 - 19/09/06
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved page 29 of 79
and for a 5V receiver:
NOTE: The UART input line TXD (rx_uart) of the GE863-QUAD/PY 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.
If VAUX is also used to supply a Camera no additional devices could be connected.
Pull-up resistors can be connected to the VAUX pad provided that the pulled-up lines are GE863-
QUAD/PY input lines connected to open collector outputs in order to avoid latch-up problems on the
GE863-QUAD/PY.
Care must be taken to avoid latch-up on the GE863-QUAD/PY 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/PY 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.