Circuit Protection of Hard Disk Drive

Design Notes:
Protection Application:
For internal hard disk drives, the drive resides within the chassis of the application. This precludes the user from contacting the data bus, so ESD is not expected to be a threat. On the power bus (typically 3.3VDC to 12VDC), the threats will be surge transients, ESD and overload currents.
Solution Description:
As shown at the left, an SMD chip fuse can be used for overload current protection, and a TVS diode or MLV for surge transients and ESD protection. The specific part numbers are determined by matching the power bus operating voltage to that of the suppressor.
Companion Solutions:
Does not apply.
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.

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