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Low Threshold For Soft Switch Turn On Protection

IP.com Disclosure Number: IPCOM000237070D
Publication Date: 2014-May-29
Document File: 2 page(s) / 74K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method for a low threshold for soft switch turn on protection is disclosed.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 62% of the total text.

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Low Threshold For Soft Switch Turn On Protection

Disclosed is a method for a low threshold for soft switch turn on protection.

Soft Switches (SS) have a defined safe operating area (SOA) which is the range of power they can dissipate safely without destroying themselves. During turn on of a SS especially into a short circuit or steep current curve it's possible for the current to spike outside of the SOA of the device. This initial inrush of current causes devices to break down as they are operating outside of the SOA and this momentary surge can last long enough to make the device fail.

Disclosed is a method for allowing for tuning of the trip threshold of the SS during turn on such that when it turns on with an abnormally low resistance or a complete short it will trip while the power being dissipated by the SS is still within the SOA of the device. This allows the designer to set the SS trip point above the normal turn on current range but below the maximum the SS can handle. This allows the SS to be able to trip during an abnormal turn on situation and trip prior to hitting the high end of the SOA. This is accomplished by adding resistor R544 as depicted in Figure 1 from the soft switch output source to the input sense and cal sense. This resistor creates a voltage divider that injects a voltage into the input sense and calibration sens lines based on the output such that it effectively raising the trip point for the current sense. The value of R544 sets the...