Network Hardware User Manual

UC864-E Hardware User Guide
1vv0300766a Rev.1 - 31/01/08
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 35 of 51
5V UART level translation
If the OEM application uses a microcontroller with a serial port (UART) that works at a voltage different
from 2.6 – 2.9V, then a circuitry has to be provided to adapt the different levels of the two sets 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:
TIP: This logic IC for the level translator and 2.6V pull-ups (not the 5V one) can be powered directly from PWRMON
line of UC864-E. Note that the TC7SZ07AE has open drain output; therefore the resistor R2 is mandatory.
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