Rainbow Electronics GE863-PY - Manual (Page 44)

GE863 Hardware User Guide
1vv0300783 Rev.0 - 10/06/08
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 44 of 80
6.7 5V UART level translation
If the OEM application uses a microcontroller with a serial port (UART) that works at a voltage different
from 2.8 - 3V, then a circuitry has to be provided to adapt the different levels of the two set of signals.
As for the RS232 translation there are a multitude of single chip translators. For example a possible
translator circuit for a 5V TRANSMITTER/RECEIVER can be:
TO TELIT
MODULE
TIP: This logic IC for the level translator and 2.8V pull-ups (not the 5V one) can be powered directly from VAUX line
of the GE863. Note that the TC7SZ07AE has open drain output, therefore the resistor R2 is mandatory.