Power switches increase power density in USB port protection duties

January 08, 2013 // By Paul Buckley
Diodes Incorporated has unveiled two programmable current-limiting power switches that provide over-current protection for two USB3.0 ports or up to four USB2.0 ports. The AP2552 and AP2553 are able to protect loads of up to a maximum of 2.1 A.

The two devices are suitable for notebook, set-top boxes, LCD TV products and other applications that require reliable over-current protection on 3.3 V and 5 V power rails. The single- channel power switches ensure accurate current setting and simple system configuration.     

To better address circuit fault protection requirements, four new power switch variants have been introduced by Diodes Incorporated: the AP2552 (low enable) and AP2553 (high enable), which limit output current to a constant safe level when output exceeds current limit threshold; and the AP2552A (low enable) and AP2553A (high enable), which provide latch-off during over-current, reverse- voltage or reverse-current conditions. All devices are available in the miniature SOT26 and U-DFN2020C-6 packages.     

The devices' high current accuracy, typically +/-6% at 1.5 A, permits closer matching of the current limit to precise system requirements, helping to reduce the need to build in unnecessary overhead. Their highly scalable current limit, from 75 mA to 2.35 A, means the power switches can be used across a wide range of design platforms, with just a single external resistor change required. For improved system robustness, the power switches exhibit a fast transient response time of 2 μs to prevent unnecessary system shutdown or restart.

The devices provide a complete protection solution for USB ports, through reverse- current blocking, under-voltage lockout, over-current, over-temperature and short-circuit features. In addition, rise and fall times are controlled to minimize current surges during turn-on and turn-off.      

Visit Diodes at www.diodes.com