PCMCIA power switch — four high-side outputs at 1 A
The Texas Instruments TPS2223PWPR is a PCMCIA power-distribution switch integrating four high-side outputs, each rated for 1 A continuous current. The serial interface controls the output sequencing; the 3:4 input-to-output ratio means one of the four outputs is switched from a separate supply path.
At 1 A per output, the 95 mOhm typical on-resistance produces about 95 mW of dissipation per channel — 380 mW total if all four are loaded. Without adequate thermal vias under the pad, the part will hit the over-temperature shutdown threshold sooner than the current limit.
Fault protection — fixed current limit and thermal shutdown
The TPS2223PWPR includes fixed current limiting and over-temperature protection. The current limit is preset — no external resistor sets the threshold. When a card draws beyond the limit, the output clamps; if the die temperature exceeds the shutdown threshold, the switch latches off until it cools. The status flag output signals a fault condition to the host controller, which can then cycle the serial interface to reset the switch.