PCMCIA power switch for multi-rail card slots
The Texas Instruments TPS2226ADBR is a PCMCIA power-interface switch designed to sequence and distribute power to PC Card or CardBus slots. It integrates four high-side outputs, each rated for 1A continuous, with a typical on-resistance of 95 mOhm per channel.
What the 95 mOhm Rds(on) means on the board
At 1A per output, the 95 mOhm typical Rds(on) produces a 95 mV voltage drop and 95 mW of self-heating per channel. The 3:4 input-to-output ratio means three supply inputs (3.3V, 5V, 12V) are distributed across four output channels — one rail is duplicated internally. This matters for BOM planning: the board must route all three supply rails to the switch, even if only two card voltages are used.
Industrial temperature and fault protection
Integrated fault protection includes fixed current limiting and over-temperature shutdown. No external sense resistor or comparator is needed — the switch limits the output current and latches off if the die temperature exceeds the threshold, then auto-retries when the die cools. This reduces the component count around the card slot by two or three passives per channel.
The TPS2226ADB (non-Reel variant) shares the same die and package — functionally identical, differing only in the shipping medium. For dual-sourcing, qualify the TPS2226ADB as a drop-in alternate; the PCB footprint and BOM position are unchanged.