User guide

UC864-E/G/WD/WDU Hardware User Guide
1vv0300766a Rev.4
- 03/02/09
Reproduction forbidden without Telit Communications S.p.A’s. written authorization - All Rights Reserved. Page 45 of 78
A power source of the internal interface voltage corresponding to the 2.6V CMOS
high level is available at the VAUX pin on the connector.
A maximum of 9 resistors of 47 KΩ pull-up can be connected to the VAUX pin,
provided no other devices are connected to it and the pulled-up lines are UC864-
E/G/WD/WDU input lines connected to open collector outputs in order to avoid latch-
up problems on UC864-E/G/WD/WDU.
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/G/WD/WDU. Note that the
TC7SZ07AE has open drain output; therefore the resistor R2 is mandatory.