Current-Limited USB Switch Protects Ports

With a low impedance of 70 mW, the MAX893L current-limited power switch for universal serial bus (USB) ports prevents PC systems from shutting down due to an overcurrent or short-circuit condition at the port. Other silicon solutions and polyfuses are said to have only 50% accuracy. Continuous worst-case current can be more than 2 A, requiring a much larger and expensive system power supply. The MAX893L has a 20% accuracy that allows designs with significantly smaller and lower cost power supplies. This device is a low-cost, pin-for-pin upgrade of the existing MAX890L. Maximum continuous current for the MAX893L is user adjustable between 200 mA and 1.2 A. The device generates a FAULT signal when it reaches current limit, thermal shutdown, or undervoltage lockout. Quiescent current is 14 mA on the on state and 0.1 mA when the switch is off. Thermal overload protection automatically limits power dissipation and junction temperature to safe levels.