computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...

, an eFuse (electronic fuse) is a microscopic fuse put into a computer chip. This technology was invented by IBM in 2004 to allow for the dynamic real-time reprogramming of chips. In the abstract, computer logic is generally "etched" or "hard-wired" onto a chip and cannot be changed after the chip has finished being manufactured. By utilizing a set of eFuses, a chip manufacturer can allow for the circuits on a chip to change while it is in operation.

Mechanism of action

eFuses can be made out of silicon or metal traces. In both cases, they work (blow) by electromigration, the phenomenon that electric flow causes the conductor material to move. Although electromigration is generally undesired in chip design as it causes failures, eFuses are made of weak traces that are designed to fail before others do.

Uses

eFuses are initially marketed by IBM as a way to provide in-chip performance tuning. If certain sub-systems fail, or are taking too long to respond, or are consuming too much power, the chip can instantly change its behavior by blowing an eFUSE. eFuses are perhaps more commonly used as a one-time

programmable ROM A programmable read-only memory (PROM) is a form of digital memory where the contents can be changed once after manufacture of the device. The data is then permanent and cannot be changed. It is one type of read-only memory (ROM). PROMs are used ...

. This ranges from writing unique information onto CPUs, or in the case of game consoles and other restricted hardware, preventing downgrades by permanently recording a newer version. The

Xbox 360 The Xbox 360 is a home video game console developed by Microsoft. As the successor to the original Xbox, it is the second console in the Xbox series. It competed with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generati ...

, Nintendo Switch,

Pixel 6 The Pixel 6 and Pixel 6 Pro are a pair of Android smartphones designed, developed, and marketed by Google as part of the Google Pixel product line. They collectively serve as the successor to the Pixel 5. The phones were first previewed in A ...

and

Samsung Galaxy S22 The Samsung Galaxy S22 is a series of Android-based smartphones designed, developed, manufactured, and marketed by Samsung Electronics as part of its Galaxy S series. Unveiled at Samsung's Galaxy Unpacked event on 9 February 2022. They collecti ...

are known for using eFuses this way.

Implementations

eFuses used for performance adjustment or unique IDs: * IBM POWER5 and

POWER6 The POWER6 is a microprocessor developed by IBM that implemented the Power ISA v.2.03. When it became available in systems in 2007, it succeeded the POWER5+ as IBM's flagship Power microprocessor. It is claimed to be part of the eCLipz projec ...

high-end RISC processors; probably all newer models *

IBM System z9 IBM System z9 is a line of IBM mainframe computers. The first models were available on September 16, 2005. The System z9 also marks the end of the previously used eServer zSeries naming convention. It was also the last mainframe compute ...

and

System z10 A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and expresse ...

mainframe processors * Sony/Toshiba/IBM

Cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

used in

PlayStation 3 The PlayStation 3 (PS3) is a home video game console developed by Sony Computer Entertainment. The successor to the PlayStation 2, it is part of the PlayStation brand of consoles. It was first released on November 11, 2006, in Japan, November ...

. Not claimed to be used for downgrade prevention. * Intel Westmere CPUs; probably all newer models * TI

MSP430 The MSP430 is a mixed-signal microcontroller family from Texas Instruments, first introduced on 14 February 1992. Built around a CPU, the MSP430 is designed for low cost and, specifically, low power consumption embedded applications. Applic ...

MCU family for Unique IDs. * TI FPD-Link SERDES for a variety of different settings. eFuses known to be used for

hardware restriction A hardware restriction (sometimes called hardware DRM) is low-level protection enforced by electronic components. The hardware restriction scheme may protect against physical or malware attacks or complement a digital rights management system imp ...

: * IBM/Microsoft

Xenon Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

CPU in the

game console. 768 bits of fuses. * NVidia

Tegra Tegra is a system on a chip (SoC) series developed by Nvidia for mobile devices such as smartphones, personal digital assistants, and mobile Internet devices. The Tegra integrates an ARM architecture central processing unit (CPU), graphics proc ...

X1 SoC used in the Nintendo Switch hybrid video game console. 256 bits of reserved fuse. *

Samsung Knox Samsung Knox is a proprietary security and management framework pre-installed on most Samsung mobile devices. Its primary purpose is to provide organizations with a toolset for managing work devices, such as employee mobile phones or interactive ...

devices detect if a non-Samsung boot path has ever run.

Variants

Resettable eFuses are used for protecting circuits. They act similarly to

resettable fuse A resettable fuse or polymeric positive temperature coefficient device (PPTC) is a passive electronic component used to protect against overcurrent faults in electronic circuits. The device is also known as a multifuse or polyfuse or polyswitch ...

s, and are generally shipped as a standalone chip package. There are several ways of implementing an antifuse in silicon: see .

References

{{DEFAULTSORT:Efuse IBM computer hardware

Mechanism of action

Uses

Implementations

Variants

See also

References