PCMCIA slot power — one chip handles Vcc and Vpp
The TPS2226DBR is a four-output high-side PCMCIA power switch array from Texas Instruments, designed to supply the 3.3 V, 5 V, and 12 V rails a PCMCIA or CardBus slot demands. It integrates four independent switches with a serial interface for output control and a status flag that reports fault conditions back to the host controller.
95 mOhm on-resistance per channel at 1 A
Each of the four outputs is rated for 1 A continuous with a typical Rds(on) of 95 mOhm. That on-resistance keeps conduction loss under 100 mW per channel at full load, which is manageable inside the 30-SSOP package without forced airflow. The 3:4 input-to-output ratio means three control signals select which of the four outputs are active — standard for PCMCIA Vcc/Vpp sequencing.
Built-in fault protection — no external sense resistor
Fixed current limiting and over-temperature shutdown are integrated on-chip. If a PCMCIA card draws excessive current or the die temperature exceeds the threshold, the switch limits the output and the status flag asserts. The host controller reads the flag via the serial interface and can power-cycle the slot. This eliminates the external current-sense resistor and comparator a discrete implementation would need.
For a BOM that already qualifies this footprint, there is no urgency to stockpile or qualify a second source — the supply chain is stable.