PCMCIA power switch — what this part does
The Texas Instruments TPS2220BDB is a dual-output high-side power switch designed for PCMCIA and CardBus slots. It integrates two 1 A rated outputs with a 4:2 input-to-output ratio, meaning four supply inputs (3.3 V, 5 V, 12 V) are routed to two switched outputs under serial interface control. The 95 mOhm typical Rds(on) keeps conduction loss low at the 1 A per-channel ceiling.
95 mOhm Rds(on) and the thermal budget
At 1 A output, the 95 mOhm typical on-resistance drops about 95 mV and dissipates 95 mW per channel.
Fault protection and the status flag
Fixed current limiting and over-temperature shutdown protect the switch and the card slot from shorts or overcurrent events. The status flag output (open-drain, active low) signals a fault condition to the host controller — useful for hot-plug sequencing where the system needs to retry or log the event.
The TPS2220BDB is officially obsolete per Texas Instruments. No successor or direct replacement order code is listed on the lifecycle record.