ExpressCard slot power — three rails, 45 mOhm floor
The TPS2231MRGPT-1 is a three-channel high-side power switch from TI, designed specifically for ExpressCard slot power sequencing. It delivers up to 1.3 A per output on the 1.5 V and 3.3 V rails, with a typical on-resistance of 45 mOhm that sets the conduction loss floor for the slot budget. The switch operates without a separate Vcc supply (Not Required), simplifying the BOM for a dedicated ExpressCard power controller. Built-in fault protection includes fixed current limiting and over-temperature shutdown, plus a Power Good and Status Flag output for system monitoring.
1.3 A per channel — three outputs, 1:1 ratio
The three outputs are configured as high-side switches with a 1:1 input-to-output ratio. The 1.3 A maximum per channel matches the ExpressCard power specification for the 3.3 V rail and the 1.5 V rail, leaving headroom for inrush and transient loads. The 45 mOhm Rds(on) at 25°C rises with junction temperature — expect about 65-70 mOhm at 85°C ambient. For a 1 A load at 85°C, the voltage drop is roughly 65-70 mV, well within the ExpressCard slot tolerance.