The MAX1946 single current-limited switch with auto-reset supplies a guaranteed 500mA load in accordance with USB specifications. The MAX1946 operates from a 2.7V to 5.5V input supply and consumes only 40μA of quiescent current when operating and only 3μA in shutdown. Selectable active-high/active-low control logic and shutdown control provide additional flexibility. An autoreset feature latches the switch off in the event of a short circuit, saving system power. The switch reactivates upon removal of the shorted condition.

The MAX1946 provides several safety features to protect the USB port. Built-in thermal-overload protection turns off the switch when the die temperature exceeds +160°C. Accurate internal current-limiting circuitry protects the input supply against both overload and short-circuit conditions. An open-drain fault signal, (active-low FAULT), notifies the microprocessor (μP) when a thermal overload, current-limit, undervoltage lockout (UVLO), or short-circuit fault occurs. A 20ms fault-blanking feature enables the circuit to ignore momentary faults, such as those caused when hot-swapping a capacitive load, preventing false alarms to the host system. The fault-blanking feature prevents fault signals from being issued when the device powers up the load.

The MAX1946 is available in a space-saving 8-pin (3mm x 3mm) TDFN package and operates over the extended (-40°C to +85°C) temperature range.