CM1402 Datasheet, PDF (9/12 Pages) California Micro Devices Corp – SIM Card EMI Filter Array with ESD Protection

CM1402
Application Information
The CM1402 provides a bidirectional filter and protector for all the signals and the power line on the SIM
(subscriber identity module) card connector. SIM cards are found in all GSM cellular phones and in some other
handheld devices or card readers. The ESD diodes protect the controller against possible ESD strikes that
may occur when the connector pins are exposed during direct contact, or during insertion of the SIM card into
the card slot. The EMI filter suppresses all high-frequency noise, preventing the unwanted EMI signals from
both entering and exiting the main board. The signals that interface with the SIM card are the Reset, the Clock
and the bidirectional data I/O, as shown in Typical Application Diagram for the SIM Card Interface.
Note: One channel of the CM1402 with a zener
diode is not shown on the diagram.
Figure 5. Typical Application Diagram for the SIM Card Interface
For best filter and ESD performance, both GND bumps (B1, B2) of the CM1402 should be directly
connected to the Ground plane. A small capacitor of about 1μF is required next to the V_CC pin of the SIM
connector in order to improve stability of the SIM card supply rail.
Rev. 3 | Page 9 of 12 | www.onsemi.com