Power switches enhance multi-port USB applications
Addressing notebook, set-top box, LCD TV, and other products requiring reliable overcurrent protection on 3.3V and 5V power rails, the AP2552 and AP2553 programmable current-limiting power switches from Diodes Incorporated provide overcurrent protection for two USB3.0 ports or up to four USB2.0 ports. Able to protect loads of up to a maximum of 2.1A, 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: 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 1.5A, 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 75mA to 2.35A, 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 just 2μs to prevent unnecessary system shutdown or restart. They 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. The AP2552/A and AP2553/A power switches are priced at $0.25 USD each in 1k quantities. Diodes Incorporated
