User's Manual

LTE Module Series
EC21 Hardware Design
EC21_Hardware_Design Confidential / Released 40 / 94
EC21 supports USIM card hot-plug via the USIM_PRESENCE pin. The function supports low level and
high level detections, and is disabled by default. Please refer to document [2] about AT+QSIMDET
command for details.
The following figure shows a reference design for USIM card interface with an 8-pin USIM card connector.
Figure 17: Reference Circuit of USIM Card Interface with an 8-Pin USIM Card Connector
If USIM card detection function is not needed, please keep USIM_PRESENCE unconnected. Areference
circuit for USIM card interface with a 6-pin USIM card connector is illustrated inthe following figure.
Figure 18: Reference Circuit of USIM Card Interface with a6-Pin USIM Card Connector