USB 2.0

Circuit Protection of USB 2.0

Design Notes:

Protection Application:
The data signals used in a USB 2.0 port vary between 0V to +0.5V, with a maximum data rate of 480Mbps.

At this data rate, the capacitance of the suppressor needs to be minimized.

The signal lines to be protected from ESD include D+ and D-. The 5VDC power bus should be protected against ESD and overcurrent events.
Solution Description:
As shown at the left, the data lines can be protected from voltage transients through a range of Littelfuse devices.

For lowest possible clamping voltage (lowest dynamic resistance), Littelfuse TVS Diode Array (SPA) devices should be used; for lowest possible capacitance Littlfuse PulseGuard (PGB) devices should be used:

Solution A) Two-channel Silicon (SPA) TVS Diode Array solution (SP3003 series shown)

Solution B) By a two-channel Polymeric PulseGuard suppressor (PGB102ST23 device)

Solution C) By discrete Polymeric PulseGuard suppressors in pair (PGB1010402 or 0603 devices)
Companion Solutions:
Other protective solutions are recommended. For the power bus a resettable 1206L Series PTC is advised for overcurrent protection, and an MLA Series Multiplayer Varistor for ESD voltage transient suppression.
Regulatory Issues:
The IEC 61000-4-2 will be the most appropriate standard that applies for this port. It supplies a test method for verifying that the end product is not susceptible to ESD events.
Unique Features:
Does not apply.
Application Warnings:
Does not apply.