18-04-2017, 10:08 AM
A Polyfuse is a one-time programmable memory component that is used in semiconductor circuits to store unique data such as chip identification numbers or memory repair data, but more generally from small to medium volume production of memory devices Read only or microcontroller chips. They were also used to allow programming of programmable logic in the arsenal. The use of fuses allowed the device to be programmed electrically some time after it was manufactured and sealed in its packaging. The above fuses had to be blown using a laser at the time the memory was made. Polyfuses were developed to replace the previous nickel-chromium (or chrome) fuses. Because the Ni-chromium contains nickel, the ni-chrome fuse once blown had a tendency to grow back and render the memory unusable.
History
The first polyfuses consisted of a polysilicon line, which was programmed by applying a high voltage (10V-15V) through the device. The resulting current physically alters the device and increases its electrical resistance. This resistance change can be detected and recorded as a logical zero. An unprogrammed polyfuse would be recorded as a logical one. These early devices had serious drawbacks such as high programming voltage and unreliability of the programmed devices.