ExpressCard power switch with integrated protection
The Texas Instruments TPS2231RGPR is a high-side power switch designed for ExpressCard slots, delivering up to 1.3 A continuous from either a 1.5 V or 3.3 V load rail. The 45 mOhm typical Rds(on) keeps conduction losses low enough that the 20-QFN package's exposed pad can dissipate the heat without forced airflow in most designs. Three independent high-side outputs share the single input, each with fixed current limiting and over-temperature protection. A Power Good output and a Status Flag provide the system controller with fault and rail-OK feedback.
Protection scheme and load budget
Fault protection is built in — current limiting (fixed, not adjustable) and thermal shutdown. No external sense resistor is needed, but the 1.3 A per-output ceiling is the hard limit; the load must stay below that at all temperatures. The Status Flag asserts low when a fault is detected, and the Power Good output indicates when the output voltage is within regulation. The switch operates without a separate Vcc/Vdd supply — it is self-powered from the load rail. The 1:1 input-to-output ratio means each output sees the full input current budget; the three outputs share the total 1.3 A, not 1.3 A each.
Without that, the over-temperature protection may trip prematurely at high ambient or full load. The QFN package is MSL-3 typical for this class; bake and reflow profiles follow JEDEC standards.