The MAX1946 is a single current-limited switch with auto-reset that provides a guaranteed 500mA load in accordance with USB specifications. It operates from a 2.7V to 5.5V input supply and consumes only 40µA of quiescent current when operating and only 3µA in shut-down. 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, (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.
The MAX1946 is a single USB switch that limits current, provides auto‑reset after a short‑circuit, and includes a 20 ms fault‑blanking circuit to ignore transient faults. It operates from 2.7 V to 5.5 V input and guarantees a 500 mA load current while consuming only 40 µA quiescent current (3 µA in shutdown).\n\nThe device is offered in an 8‑pin (3 mm × 3 mm) TDFN package and works over an extended temperature range of –40 °C to +85 °C. Built‑in thermal‑overload protection shuts the switch off at +160 °C, and the open‑drain FAULT pin signals overload, short‑circuit, UVLO, or thermal‑shutdown conditions.
| Supply Voltage Range | 2.7 V to 5.5 V |
|---|---|
| Continuous Load Current | 500 mA |
| Shutdown Supply Current | 3 µA |
| Thermal‑overload Shutdown Temperature | +160 °C |
| Fault‑Blanking Time | 20 ms |
| Package | 8‑pin TDFN (3 mm × 3 mm) |
The MAX1946 guarantees a 500 mA load current in accordance with USB specifications.
When a short‑circuit occurs, the switch latches off and after the fault‑blanking period (20 ms) the device automatically restarts, turning the output back on.
The device operates from –40 °C to +85 °C.