Electronic Design

Dual USB-Port Switches Handle 1.2 A, Protect Supplies From Faults

A novel current-limited switch for host USB ports delivers up to 1.2 A of output current for each of two channels. Developed by Maxim Semiconductor, the MAX1558 includes an accurate, programmable, internal current-limiting circuit that protects the input supply against overload and short-circuit conditions.

Independent fault signals notify the microprocessor when thermal-overload, current-limit, undervoltage-lockout, or short-circuit faults occur. The switch runs on 2.7 to 5.5 V, draws 45-µA quiescent current (3 µA in standby), and exhibits 55-m(omega) switch resistance. A 20-ms fault-blanking feature lets it ignore momentary faults, such as those caused by hot-swapping a capacitive load. Also, an autoreset feature automatically restarts the output once a short-circuit or overload condition is removed.

The MAX1558 operates from ­40°C to 85°C. It comes in a 3- by 3-mm, 10-pin TDFN package. Prices start at $1.10 in quantities of 1000.

Maxim Semiconductor

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