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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The relatively large amounts of process variability inherent in high-volume wafer fabrication can prevent high-precision circuitry from meeting specification.

Again, this consideration primarily applies polhfuse resistors used in transient suppressors and ESD structures. Extreme overheating can even cause open-circuit failures. The polysilicon fuse must be heavily doped to obtain a sufficiently low resistance typical metal fuse and B a polysilicon fuse. The polysilicon is laid out as a small resistor connecting two bondpads. The length of poly resistors should also satisfy equations 5. By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

This model includes a resistor, R 2,that models the effects of tank resistance, and diodes, D3 and D 4, that model the distributed nature of the tank-substrate junction. The pinchoff voltage polyfyse which this occurs depends upon epi thickness, epi doping, and base junction depth.

The corrections for nonuniform current flow near the contacts can usually be ignored because these rarely amount t o more than a half square. I The drawn length Ld of an HSR resistor is customarily measured between the inner edges of the two base heads. Pinch resistors are typically used to construct high-value resistors that cannot be economically implemented using other diffusions.


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No corrections are required for nonuniform current flow at the ends of the resistor. Both cases assume that the ground pad is used if program the fuses. Emitter resistors are frequently employed in standard bipolar to ballast power transistors and to serve as current sense resistors. True, the errors caused by nonuniform current flow are smaller for dogbones than for either strip or serpentine resistors, but this does not actually improve the accuracy of the resistor.

Post as a guest Name. Both polysilicon and aluminum fuses are difficult to program after encapsulation.

future scope of polyfuse pdf

For these reasons, different resistance materials cannot be arbitrarily substituted for one another. The metal plate for this contact is also elongated so that fuyure covers the contact no matter where the latter is located.

The time required to complete the processing of the tweaked wafers is usually much less than the time required to fabricate a new wafer lot. Circuit designers usually select appropriate materials for each resistor and mark their schematics accordingly. Mc raw- ill,p. The layout in Figure 5. For example, the resistor normally trimmed in a Brokaw bandgap31 connects between the emitter of an NPN transistor and ground.

This pf results from the presence of a potential barrier between the resistance material and the metallization. Resistor tweaks represent an exception to this rule because they need not affect the entire mask set.

The resistor segments should be binary weighted to ensure that the achievable values of resistance are uniformly spaced across the trim range.

Not only does this impair the blowing of the fuses, but it also makes them prone to regrowth because conductive material remains near them. The networks used for laser trimming are similar to those shown in Figure 5.

Resettable fuse – Wikipedia

The approximate value of the 7 8 Glaser,et al. Metal fuses incorporating refractory barrier metal can also be programmed reliably; the aluminum is ejected first, but the thin refractory metal soon follows. This tankless style of emitter resistor can also be constructed in standard bipolar by coding base entirely across the tank that contains an emitter resistor. Under these conditions, the resistance of the barrier regions between grains becomes a function of the voltage drop across the resistor.


Resettable fuse

The leads of the resistor are only extensions of the resistance layer, so any excess lead 5. Lay out a serpentine high-sheet poly-2 resistor with a width of 4um and a value of Assume the body of the resistor has a sheet resistance of and the NSDdoped heads have a sheet resistance of allow for misalignment,the overlap of NSD over contact must equal at least 2um.

NBL not only helps minimize debiasing, but it also acts as a barrier to’ minority carriers and consequently enhances latchup immunity. This opening represents a potential pathway for contaminants to enter the die, but if it is omitted, the vaporized metal cannot escape and the fuse sometimes reforms after programming. San Francisco Bay Area Council The resistance of the resulting composite structure can be computed using formulas similar to those used for HSR resistors Section 5.

Despite their reduced dimensions, trimpads still require substantial die area. In summary, the pinch resistor is a marginal device used primarily to construct compact high-value resistors.

This longitudinal cut causes a more gradual increase in resistance and therefore allows finer trim resolution. The precision of deeply diffused resistors depends on outdiffusion as it does on linewidth control. Small-grained poly films therefore exhibit higher resistivities than large-grained films.