Texas Instruments TXS4558RUKR

Overview

TXS4558RUKR from Texas Instruments is a dual-SIM card power supply IC with integrated level translation and dual selectable-output LDOs. It supports ISO/IEC 7816-3-compliant Smart Card interfaces for GSM and 3G mobile handsets, delivers 1.8 V or 2.95 V outputs (50 mA each), operates from 2.3 V–5.5 V battery input, and features 8 kV HBM ESD protection on SIM pins. It enables dual-SIM operation in space-constrained mobile baseband designs.

For engineers reviewing the TXS4558RUKR datasheet, TXS4558RUKR pinout, TXS4558RUKR application, or TXS4558RUKR equivalent, key selection criteria include dual-LDO voltage selectability (1.8 V / 2.95 V), isolated clock stop mode per SIM, GPIO-controlled channel switching (CSEL/ENx/VSELx), and QFN-20 (3 mm × 3 mm) thermal-pad package compatibility with mobile PCB layout constraints.

Technical Context

The TXS4558RUKR integrates two independent LDO regulators-each programmable to 1.8 V (Class-C) or 2.95 V (Class-B) via dedicated VSEL1/VSEL2 inputs-and a bidirectional level translator supporting VCC (1.65 V–3.3 V) to VSIM domains. Its control logic accepts GPIO commands (CSEL, EN1/EN2, CLKRUN1/CLKRUN2) to manage SIM activation, clock gating, and shutdown sequencing per ISO 7816-3.

Each SIM interface includes dedicated push-pull RST/CLK outputs and open-drain I/O with internal pull-ups (7.4–8.7 kΩ) and active pull-downs (2 kΩ), while the device maintains <100 mV dropout at 50 mA load and achieves >40 dB PSRR at 10 kHz under 1 µF output capacitance.

Key Specifications

Pinout & Package

TXS4558RUKR uses a 20-pin WQFN (RUK) package with 3 mm × 3 mm footprint, 0.4 mm pitch, and an exposed center thermal pad that must be electrically connected to GND for thermal and mechanical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-SIM power management applications.

Compared with MAX1608ETE+ and TPS65132ARSLR, the TXS4558RUKR uniquely integrates dual LDOs, bidirectional level translation, ISO 7816-3-compliant control logic, and SIM-hardened I/O in one 3 mm × 3 mm package - delivering full dual-SIM functionality without external components or firmware overhead.

Availability

TXS4558RUKR is available at Aetrix Electronics and suitable for smartphone dual-SIM support, mobile hotspot redundancy, and IoT cellular gateway designs requiring stable component supply across extended production lifecycles.

Supply support for TXS4558RUKR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies with over 50 years of innovation in high-reliability IC design.

The TXS4558RUKR belongs to TI's Smart Card Interface product line, engineered specifically to simplify dual-SIM integration in mobile handsets by consolidating power regulation, level translation, and ISO-compliant control into a single compact IC.

FAQ

What is the primary function of the TXS4558RUKR in a mobile handset design?

The TXS4558RUKR serves as a complete dual-SIM interface IC, integrating two independently configurable LDOs (1.8 V/2.95 V), bidirectional level translation between baseband and SIM domains, and hardware-based ISO 7816-3-compliant activation/deactivation sequencing. In a mobile handset, it replaces multiple discrete regulators, translators, and GPIO logic, enabling compact dual-SIM support without firmware intervention. The TXS4558RUKR directly interfaces with the baseband processor and two physical SIM cards while managing power, signal levels, and timing per industry standards.

How does the TXS4558RUKR handle voltage selection for SIM1 and SIM2 independently?

The TXS4558RUKR uses dedicated digital inputs VSEL1 and VSEL2 to set the output voltage of each LDO: a LOW signal selects 1.8 V (Class-C), and a HIGH signal selects 2.95 V (Class-B). These pins operate independently, allowing SIM1 and SIM2 to run at different voltage classes simultaneously - for example, SIM1 at 1.8 V and SIM2 at 2.95 V. This configuration is retained across power cycles and does not require register programming. The TXS4558RUKR applies the selected voltage directly to VSIM1 and VSIM2 pins, which power the respective SIM card's VCC and serve as the level-shift reference for associated I/O, CLK, and RST signals.

What is the role of the CLKRUN1 and CLKRUN2 pins on the TXS4558RUKR?

The CLKRUN1 and CLKRUN2 pins control whether the SIM1_CLK and SIM2_CLK outputs remain active or are forced low when their respective SIM channels are deselected via the CSEL pin. When CLKRUNx is HIGH, the baseband CLK signal continues to pass through to SIMx_CLK regardless of CSEL state - useful for maintaining clock presence during handover. When CLKRUNx is LOW, SIMx_CLK is driven low two clock cycles after CSEL deselects that SIM - reducing EMI and power draw. This per-channel clock gating is implemented in hardware and requires no software coordination. The TXS4558RUKR uses these pins to meet varying GSM/3G clock persistence requirements without modifying baseband timing behavior.

Does the TXS4558RUKR support hot swapping of SIM cards, and how is it implemented?

Yes, the TXS4558RUKR supports safe SIM hot swapping through its hardware-enforced ISO 7816-3-compliant shutdown sequence. When EN1 or EN2 is driven LOW, the device executes a precise deactivation order: first asserting SIMxRST low, then disabling SIMxCLK after two clock cycles (or ~9 µs if CLK inactive), followed by pulling SIMxIO low, and finally disabling the VSIMx LDO. This sequence prevents data corruption and bus contention. The TXS4558RUKR also includes 8 kV HBM ESD protection on all SIM-facing pins (SIM1_I/O, SIM1_CLK, SIM1_RST, etc.) to withstand insertion/removal transients. No external circuitry or host processor intervention is required - the entire process is autonomous and deterministic.

What are the thermal design requirements for the TXS4558RUKR's exposed pad?

The TXS4558RUKR's exposed thermal pad (Pin 21) must be electrically connected to the PCB's ground plane using solder - not left floating or tied only through thermal vias. TI specifies this connection as mandatory for both thermal performance and mechanical reliability. Recommended layout includes a solid copper area under the pad, filled with ≥4 thermal vias (0.2 mm diameter, spaced evenly), each connected to an internal or bottom-layer ground plane. The solder stencil should provide 78% paste coverage on the pad to ensure void-free solder joints. Failure to properly connect the pad results in junction temperature exceeding 125°C under 50 mA load, triggering thermal shutdown. The TXS4558RUKR's thermal protection circuit cycles ON/OFF above ~160°C, but sustained operation above 125°C degrades long-term reliability.