The MAX1600/MAX1603 DC power-switching ICs contain a network of low-resistance MOSFET switches that deliver selectable VCC and VPP voltages to two CardBus or PC Card host sockets. Key features include ultra-low-resistance switches, small packaging, softswitching action, and compliance with PCMCIA specifications for 3V/5V switching. 3.3V-only power switching for fast, 32-bit CardBus applications is supported in two ways: stiff, low-resistance 3.3V switches allow high 3.3V load currents (up to 1A); and completely independent internal charge pumps let the 3.3V switch operate normally, even if the +5V and +12V supplies are disconnected or turned off to conserve power. The internal charge pumps are regulating types that draw reduced input current when the VCC switches are static. Also, power consumption is automatically reduced to 10A max when the control logic inputs are programmed to high-Z or GND states, unlike other solutions that may require a separate shutdown-control input.