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Design >> Analog Design >> where has eFuse info
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Message started by ssm on Oct 15^th, 2009, 2:33pm

Title: where has eFuse info
Post by ssm on Oct 15^th, 2009, 2:33pm

Previously get some useful hints from this board so I want to give it a try here again, after much resultless searches.

I am using electrically programmable poly fuse (5-6V) for analog designs (3.3V), but not much information from foundry . Wondering any book or good sources discussing the fuse circuits designs ?

Thanks in advance,

ssm

Title: Re: where has eFuse info
Post by loose-electron on Oct 19^th, 2009, 9:30am

Link blowing for fuses have some reliability problems - Suggest doing some processing of the signal and not just using it as a digital state:

Think - Wheatstone bridge, with one of the 4 elements being the poly link, and the bridge intentionally out of balance when the link has not been blown.

The output of the bridge feeds into a comparator.

When the link is blown, comparator output changes.

This type of design allows the blown link to still function if the link blows open cleanly, or only shifts in resistance value some.

Other reliability problems here are unique to the foundry, but the above method gets you around a lot of the problems with links not fully opening, or changing value (think particle contamination) after being blown or cut open.

Title: Re: where has eFuse info
Post by thechopper on Oct 19^th, 2009, 8:57pm

Blowing time is another concern, in particular with poly fuses. If the blowing pulse is not long enough you might get partially blown fuses, where the fuse resistance does not look like a totally opened fuse.
Generally a large capacitor is placed at the pin at which you apply the blowing pulses.

Best
Tosei