NCP362 protects USB 2.0s from electrical surge

An ON Semiconductor product story

Edited by the Electronicstalk editorial team May 4, 2009

ON Semiconductor has released the NCP362, an overvoltage protection (OVP) device with integrated current protection and high-speed electrostatic discharge (ESD) protection.

It is suitable for USB 2.0 applications in portable, telecom, consumer and computing systems.

This integrated device improves the safety of USB ports by streamlining design in portable electronics.

It does this by eliminating the need for standalone OVP, overcurrent protection (OCP) and transient voltage suppressor (TVS) components that have - until now - been necessary to protect vulnerable portable devices against electrical surge damage and electronic discharge from host, wall adapters, human body and unsuitable after-market AC-DC adapters.

The NCP362, which is placed behind the USB or bottom connector, provides +20V front-end protection for the downstream USB port, thanks to an integrated power Mosfet that can handle 500 milliamperes (mA).

Because long cables can induce ringing (due to serial inductance in the USB cable), the NCP362 has been designed to open the VBUS line when the voltage transient exceeds the internal overvoltage threshold (OVLO), which is internally set to 5.675V.

This threshold value can be changed by a metal tweak if a different value is needed for a specific application.

In addition, OCP is available, opening the internal Mosfet if the downstream VBUS's load exceeds 750mA, supporting 500mA - continuous - for the USB ports.

This current clamp value can also be adjusted to a lower value to comply with a 100mA single or dual port.

Both protections are very fast - at fewer than 100 nano-seconds - offering an efficient protection level for the downstream transceiver, battery charger devices or lithium battery to be charged.

In addition, the NCP362 offers system level IEC 61000-4-2 +/-15 kilovolts (kV) ESD protection.

The part integrates high-speed ESD diodes for data lines (D+ and D-) and TVS for VBUS pin of the USB ports.

Due to the low capacitance of integrated ESD diodes (0.5 pico-farads/pF), this device is compliant with the USB 2.0 protocol.

Depending on the selected NCP362x version (see ordering table in the product datasheet), VBUS TVS or D+/D- (or both) are integrated in the same package.