Dual-Supply 2:1 SIM Card Multiplexer/Translator with Automatic Detect and slot dedicated dual LDO

The TXS02326A is a complete dual-supply standby Smart Identity Module (SIM) card solution for interfacing wireless baseband processors with two individual SIM subscriber cards to store data for mobile handset applications. It is a custom device which is used to extend a single SIM/UICC interface to support two SIMs/UICCs.

The device complies with ISO/IEC Smart-Card Interface requirements as well as GSM and 3G mobile standards. It includes a high-speed level translator capable of supporting Class-B (2.95-V) and Class-C (1.8-V) interfaces; two low-dropout (LDO) voltage regulators with output voltages that are selectable between 2.95-V Class-B and 1.8-V Class-C interfaces; an integrated "fast-mode" 400 kb/s "slave" I2C control register interface, for configuration purposes; and a 32-kHz clock input, for internal timing generation. The TXS02326A also includes a shutdown input and a comparator input that detects battery pack removal to safely power-down the two SIM cards. The shutdown input and comparator input are equipped with two programmable debounce counter (i.e. BSI input and SDN input) circuits realized by an 8 bit counter.

The voltage-level translator has two supply voltage pins. VDDIO sets the reference for the baseband interface and can be operated from 1.7-V to 3.3-V. VSIM1 and VSIM2 are programmed to either 1.8-V or 2.95-V, each supplied by an independent internal LDO regulator. The integrated LDO accepts input battery voltages from 2.3-V to 5.5-V and outputs up to 50 mA to the B-side circuitry and external Class-B or Class-C SIM card.