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 72 of 78
13. Application guide for SIM interface
When designing SIM interface on the application boards, the following schematics
are recommended.
All the components in the application side (dotted line above) should be included into
the application board and the recommended values should be referred as well.
Special attention should be paid to the value of Resistor R1.
3GPP specifications define that the rise time and the fall time of the IO signal shall
not exceed 1 us.
Resistor R1 is very closely related to the rise time and the fall time of the SIMIO
signal. It can differ depending on the application board therefore it should be
considered at the customer point of view. Telit highly recommends that the
customers should verify the relating specification when they design.
To make it easy to understand, Telit presents the following results which is based on
the UC864-E/G/WD/WDU with Telit EVK.
This result represents the deviation by R1 regarding the rise time and the fall time of
SIMIO signal.