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Fuse usage

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Newbie level 4
Sep 23, 2022
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this question is regarding the use of fuses in SoC or ASIC's
I have noticed that in newer designs, the number of fuse bits are quite high. As high as 20Kb for example
I can understand fuse values being used for ramp repair etc. but I see a lot of bits being used for IP configuration (e.g. to enable a feature or disable).
Normally, such configurations can be done using configuration and control registers.

So, the question is what is the reason why the new designs have such a large number of fuse bits?

fuse can be used to differentiate product from the same die.
fuse can be used to store life cycle state....
At 20K bits, what you likely have is a fuse PROM bank
(like for boot code?). Trim bits for analog, which is a common
use for fuses, would need far fewer.

It was difficult to do on-chip fuse programming back in the
older CMOS generations, but now programming-switch
size for current has gone way up, while neck current to
fuse minimum polycide or metal has gone way down, so
fuses have become net-area and -reliability winners again.
Back at the 250nm and 500nm generations I could only
get enough current-to-blow into a fuse that sat across a
pad-pair (generally, one of them would be GND and the
rest, used to control CMOS switches in analog blocks).
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