Storage Architecture
Banks of microscopic fuses integrated directly into a semiconductor provide a permanent way to store configuration data and security codes. An efuse array consists of rows and columns of metal or polysilicon elements that can be blown by a controlled electrical pulse. This process is irreversible once the fuse is opened.
Programming Operation
Writing data to the chip involves passing a high current through specific fuses to change their resistance from a low state to a high state. The controller in the efuse array manages the timing and magnitude of the current to ensure the fuse is cleanly severed without damaging the surrounding circuitry. This programming typically happens during the final stages of manufacturing.
Trimming Function
Analog circuits often require precise adjustments to their internal voltages or current references to overcome the variations inherent in the silicon process. The efuse array provides a mechanism for trimming these values after the device has been packaged and tested. Technicians measure the initial performance of the circuit and then blow the appropriate fuses to bring the output into the desired range.
Reliability Factor
Stability of the programmed state is critical for the long term operation of the device. Fuses are designed to remain in their high resistance state for the entire life of the product.
