User's Manual

UMTS/HSPA Module Series
UG95 Hardware Design
UG95_Hardware_Design Confidential / Released 39 / 67
In order to enhance the reliability and availability of the USIM card in customer’s application, please follow
the following criterion in the USIM circuit design:
 Keep layout of USIM card as close as possible to the module. Assure the possibility of the length of
the trace is less than 200mm.
 Keep USIM card signal away from RF and VBAT alignment.
 Assure the ground between module and USIM holder short and wide. Keep the width of ground and
USIM_VDD no less than 0.5mm to maintain the same electric potential. The decouple capacitor of
USIM_VDD should be less than 1uF and must be near to USIM holder.
 To avoid cross-talk between USIM_DATA and USIM_CLK, keep them away with each other and
shield them with surrounded ground.
 In order to offer good ESD protection, it is recommended to add TVS such as WILL
(http://www.willsemi.com) ESDA6V8AV6. The 22Ω resistors should be added in series between the
module and the USIM card so as to suppress the EMI spurious transmission and enhance the ESD
protection.
3.11.2. Design Considerations for USIM Card Holder
For 8-pin USIM card holder, it is recommended to use Molex 91228. Please visit http://www.molex.com for
more information.
Figure 22: Molex 91228 USIM Card Holder