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 drawn length and width can be used to determine the approximate value of the resistor using equation 5. The fuse must have a total resistance of no more than to ensure reliable programming with a 10V pulse.
Provision can be made for tweaking resistors by means of sliding contacts, sliding heads, trombone slides, and metal option jumpers. The value of the resistor equals where Rs is the sheet resistance futurr the HSR implant, Wb is the width bias, and Lb is the length bias.
Poly resistors may also exhibit nonlinearities if they are so short that appreciable voltage drops can appear across individual poly grains. Resistivities vary substantially depending on the conditions of preparation;for example, bulk resistivities of pure materials are considerably smaller than the thin-film values Values for Cu, Au, Al, PtSi: After programming, the fuse becomes an open circuit.
Nonuniform current flow at the juncture of the two segments introduces a small error, but this can be ignored because the resistor will probably be trimmed anyway. This effect can be minimized by making the width of the contact Wc equal to the width of the resistor Wd and by minimizing the overlap W o of the resistor head over the contact.
Contact resistance,assuming Al-Cu-Si metallization. Streetman, Solid State Electronic Devices, 2nd ed. The ;olyfuse for resistance can now be rewritten as follows: Unless the circuitry is specifically designed to switch at low voltages, the look-ahead process may pplyfuse the poly fuse, causing it to increase in value to the point where it can no longer be reliably programmed.
An examination of each of these terms will show which must be taken into account duture order to accurately predict the value of a resistor. Conductivity modulation also affects HSR resistors.
The first is to use a polyfuse, and the second is to use a chip, called a current monitor and protection chip. Since the molten filament moves at a finite speed, it is theoretically possible to halt the programming process before the gap between the contacts is fully bridged.
These less-significant factors will be discussed in Chapter 7. The dimensions of a resistor vary because of photolithographic inaccuracies and nonuniform etch rates.
The resistance of an elongated base head can be approximated using equation 5. A redesign of a circuit that affects only component values is called a tweak. NBL should always be placed beneath a base pinch resistor because NBL push helps increase its sheet resistance.
Our project brings forward this system to automate the wiper system having no need for manual intervention. Because larger voltages are generally required to program Zeners than fuses, care must be taken to ensure that the circuitry connected to the trim network can withstand a momentary overvoltage condition.
5The art of Analog Layout(Resistors)_图文_百度文库
Poly resistors that use a silicide block mask can also be adjusted by sliding the silicide block toward or away from the contact. If the effective width were increased to 10um, then the variability would be reduced to The tank and NBL geometries can sco;e beneath the trimpads. The Zeners must be oriented so that they remain reverse-biased during normal operation, and the voltage placed across each Zener must not exceed the base-emitter breakdown voltage.
The resistance Fuutre added by a single contact having width Wc and length LC equals 18 where R s is the sheet resistance of the resistor material, is the specific contact resistance, and coth represents the hyperbolic cotangent function.
It may also be software that is a complement to a medical device and contributes directly to the patient’s treatment by performing analysis or poyfuse diagnostic treatment or functionality that replaces the decision and judgment of a physician. Polysilicon does not experience tank modulation, and conductivity modulation is generally negligible for sheet resistances of less than 5.
Why do you want to know? The resulting power dissipation in a very limited volume of silicon results in extreme localized heating. By moving the laser incrementally while performing a series of shots, a continuous line of high-resistance material can be formed.
Top-metal leads cannot cross thin-film resistors without shorting to them, but lower levels of metal are not so constrained.
John Wiley and Sons, But when any fault occur in cable,then it is difficult to locate fault. This article needs additional fuutre for verification. The optimal sheet resistance lies in the neighborhood of which allows substantial area savings without having to worry too much about field plates or lead routing.
future scope of polyfuse pdf
Below is stripped version of available tagged cloud pages from web pages Base pinch resistors are formed from the region corresponding to the neutral base of an NPN transistor.
McGraw-Hill,p. The quantity AR represents the increase in resistance caused by nonuniform current flow at both ends of the resistor.