SIM card interface

The LTE modem supports the universal integrated circuit card (UICC) interface.

Only UICCs with electrical interfaces specified in ISO/IEC 7816-3 are supported. UICCs with IC-USB, CLF or MMC interfaces are not supported.

The supported UICC/eUICC interface is compliant with:

• ETSI TS 102 221: Smart Cards; UICC-Terminal interface; Physical and logical characteristics
• ETSI TS 103 383: Smart Cards; Embedded UICC; Requirements Specification

The physical interface towards the eUICC is the same as towards the removable UICC.

Only the class C (supply voltage 1.8 V nominal) operation is supported. Support for the legacy class B (supply voltage 3.0 V nominal) operation must be built with external components, including the external power supply and the level shifters towards the LTE modem UICC interface.

The LTE modem supports powering down the UICC during PSM and eDRX idle mode if the UICC supports this feature as specified in 3GPP TS 24.301. To reach the lowest total power consumption of the complete cellular IoT product, only UICCs supporting power down mode during PSM and eDRX idle mode sleep intervals should be considered.

The LTE modem controls the physical interfaces towards the UICC and implements the transport protocol over the four-pin ISO/IEC 7816-3 interface:

• VCC (power supply) – LTE modem drives this
• CLK (clock signal) – LTE modem drives this
• RST (reset signal) – LTE modem drives this
• I/O (input/output serial data) – Bi-directional

The interface and the connections between the LTE modem, UICC connector, and the ESD device is shown in the following figure.

Figure 1. Connections between LTE modem, card connector, and the ESD device

Only standard transmission speeds are supported as specified in ETSI TS 102 221.

An electrostatic discharge (ESD) protection device compatible with UICC cards must be used between the removable card and the LTE modem, to protect LTE modem against harmful ESD from the card connector.