Smart protection switch is suitable for Type-C

Two protection switches have been released by Alpha and Omega Semiconductor (AOS) for Type-C Power Delivery (PD) high voltage sink protection. The AOZ13984DI-02 and AOZ13987DI-02 switches are smart protection switches in a single small thermally enhanced 3.0 x 3.0mm DFN package.

They use the company’s advanced co-packaging technology and combine a high-performance IC with protection features and its latest high safe operating area (SOA) trench MOSFET.  Both devices offer low RDSon of 20mOhm (AOZ13987DI-02) and 33mΩ (AOZ13984DI-02) back-to-back MOSFETs to block any reverse current under fault conditions. They are capable of up to 28V absolute maximum voltage.

Typically, a USB Type-C port adaptor supplies 5.0V at plug-in. Once plugged in, the client device negotiates a higher voltage for fast charging. The rise time for VBUS voltage from 5.0V to the final target value is very slow per the USB standard. Typical Type C protection switch designs that rely on a comparator to detect a voltage drop across the back-to-back power switches do not work with slow rising VBUS voltages and are susceptible to system-level faults, explained AOS. To counter this, system designs can implement an ideal diode approach. Typically implemented discretely. They require many external components and lack protection features that are possible with an IC-based approach.

The AOZ13987DI-02 and AOZ13984DI-02 feature ideal diode true reverse current blocking (IDTRCB), which allows no reverse current at any conditions. They also feature 28V absolute maximum voltage with start-up SOA management.

“The thinner profile, higher power, and greater flexibility offered by USB Type-C and USB PD 3.0 standards have allowed many notebook computers to only use Type-C ports for both power delivery and as a high-speed interface,” explained Peter Cheng, power IC senior marketing director at AOS. This eliminates the need for a dedicated power connector but the combination of TrenchFET technology with IC design results in a compact, efficient solution, he added.”

In addition to ideal diode true reverse current blocking, the switches have under-voltage lock-out, over-voltage protection and thermal shutdown protection. Other features are a programmable soft-start and start-up SOA management.

The AOZ13987DI-02 and AOZ13984DI-02 are available now in a 3.0 x 3.0mm DFN-12L package and in production quantities with a lead time of 14 weeks.

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