A resettable fuse is a polymeric positive temperature coefficient (PPTC) device that 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. . Beam deflection tube · Charactron · Iconoscope · Magic eye tube. Read about ‘F1/F2 polyfuses gone’ on elementcom. are made to the Raspberry Pi’s hardware in the future and how they are justified by. Isoloop magnetic couplers 6) Working 7) Digital isolators 8) Advantages 9) Applications 10) Future scope 11) conclusion 12) References; 3.

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This information can be summarized as a set of design guidelines: Trombone Slides Serpentine resistors can be sclpe by sliding turns inward or outward, a technique colorfully referred to as a trombone slide.

This is very wasteful of area, and constitutes yet another reason for considering alternative resistors such as epi-pinch resistors or narrow HSR resistors. The Zeners appear as open circuits until they are programmed, after which they appear as shorts. This page was last edited on 9 Octoberat The aluminum metal contacting the silicon melts, and a molten filament of aluminum-silicon alloy flows underneath the oxide and bridges the gap between the contacts Figure 5.

For example, a resistor containing ten squares of material will have a value of Although the sheet resistance of a homogeneous film can be easily computed, many integrated resistors consist of inhomogeneous diffusions. Each technique involves a different mask, and no one method can adjust all types of resistors. Epi and well pinch resistors are not used in large numbers. Leads can be routed across base resistors without causing significant conductivity modulation. The sheet control of the resistor thus approximately equals the variation of metal thickness.

The width bias Wb models the difference between the drawn width and the effective width. The laser beam first moves laterally across the resistor.


The resistor therefore gains value. The device is also known as a multifuse or polyfuse or polyswitch.

Resettable fuse

Such fractures cause the current flow to stop and prevent fufure programming. The trims should be placed on the grounded end of the resistor so that transients must pass through the rest of the resistor before reaching the base-emitter junction.

Nonuniform current od at the juncture of the two segments introduces a small error, but this can be ignored because the resistor will probably be trimmed anyway. Based on this experiment, Zener zaps appear unsuitable for processes employing refractory barrier metal or silicided contacts. Assume that the emitter contact has a width of 8um and minimize all other dimensions Assume the trimpads require openings in the protective overcoat.

These differences are most pronounced in lightly doped poly, which may exhibit a resistivity that is several orders of magnitude greater than similarly doped monocrystalline silicon. Here is my workaround the wire should be shorter: This technique can be extended to encompass resistors of unequal values by dividing them into multiple sections occupying separate tanks.

What is the sheet resistance of a aluminum film if its resistivity equals Suppose a standard bipolar base resistor has a value of a sheet resistance of a uniform width of 8um, and two contacts.

The effects of lateral nonuniform current flow differ for dogbone and strip resistors. HSR implants come in a range of sheet resistances. Sliding contacts are somewhat more difficult to construct if the resistor uses enlarged heads.

The approximate value of the 7 8 Glaser,et al. Even though the emitter resistor may electrically connect to the tank, the difference in resistivities ensures that most of the current flows through the resistor and not through the tank.

This not only eliminates a potential pathway for contaminants to enter the die but also raises the possibility of trimming packaged units. Their sheet resistances typically range from polyvuse to so there is no difficulty in directly contacting the emitter diffusion.


The resistance of each base head, R is computed separately since it does poljfuse depend on the HSR sheet resistance. Process Variation The value of a resistor depends upon its sheet resistance and its dimensions. Current does not flow uniformly around the bends in a serpentine resistor.

The base sheet in BiCMOS and advanced bipolar processes is usually somewhat higher than standard bipolar to so reliable Ohmic contact requires the addition of a more heavily doped diffusion beneath the contacts. Dogbone resistors do not pack as densely as strip or serpentine resistors Figure 5. For a theoretical analysis, see Runyan, et al.

Potentiometer digital Variable capacitor Varicap. Epi Pinch Resistors An epi pinch resistor resembles a base pinch resistor in that it consists of a resistive region pinched between two junctions to increase its sheet resistance.

Diffused resistors can also withstand larger power transients than poly resistors because the thermal conductivity of silicon far exceeds that of the field oxide. Trimming Resistors Resistors can be trimmed using fuses, Zener zaps, or laser trims. The emitter and base contacts should be placed as close as layout rules allow to facilitate the zapping process.

Resettable fuse – Wikipedia

Elongated base heads are also useful when the HSR resistor is too short to accommodate all of the leads that must cross it. The trip current is the current at which the device is guaranteed to trip. Consider both self-heating and granularity. The polysilicon is laid out as a small resistor connecting two bondpads. From Wikipedia, the free encyclopedia. Sign up or log in Sign up using Google. The width bias is negative because the out-diffusion of the isolation regions encroaches upon the pinched resistance layer.