The MAX1601/MAX1604 DC power-switching ICs contain a network of low-resistance MOSFET switches that deliver selectable V_CC and V_P-P voltages to two CardBus or PC Card host sockets. Key features include ultra-low-resistance switches, small packaging, soft-switching 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 V_CC switches are static. Also, power consumption is automatically reduced to 10µA max when the switches are programmed to high-Z or GND states over the serial interface, unlike other solutions that may require a separate shutdown-control input.

Other key features include guaranteed specifications for output current limit level, and guaranteed specifications for output rise/fall times (in compliance with PCMCIA specifications). Reliability is enhanced by thermal-overload protection, accurate current limiting, an overcurrent-fault flag output, undervoltage lockout, and extra ESD protection at the V_CC/V_P-P outputs. The SMBus™ serial interface is flexible, and can tolerate logic input levels in excess of the positive supply rail.

The MAX1604 and MAX1601 are identical, except for the MAX1604's VY switch, which has roughly three-times the on-resistance (typically 140mΩ). The MAX1601/MAX1604 fit two complete CardBus/PCMCIA switches into a space-saving, narrow (0.2in. or 5mm wide) SSOP package.