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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Thin-film resistors are preferable to all others, so designs that employ them will not require most other types of resistors.
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This reverse-biases the tank-substratejunctions,but each resistor sees a different relative tank bias andexperiences a different amount of tank modulation. Leads connecting to outside pins should not route across thin-oxide emitter diffusions unless they connect to them Section 4.
A notched bar, B tophat, C looped layout,and D ladder layout.
Some designers have attempted to use remotely programmed poly fuses to implement look-ahead trimming. These resistors should bc laid out on field oxide because any steps in the underlying surface may cause significant variability. Base Pinch Resistors Base pinch resistors can be scpe in standard bipolar Figure 3.
Our system uses rain sensor to detect rain, this signal is then processed by microcontroller to take the desired action. The resulting devices closely resemble epi-pinch resistors, but they or more and lower pinchoff usually possess much higher initial resistances voltages 20V or less. Capacitive and inductive coupling inevitably occur at higher frequencies, and some types of resistors also experience junction leakage.
A sliding contact can still be made as long as the material of the head has the same resistivity as the material of the body Figure 5. The value of most resistors can be determined by means of futurr simple computation involving width and length. Resistivity and Sheet Resistance.
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Resistors For a typical 40V standard bipolar process, the epi pinchoff voltage lies between 20 and 40V. Tweaking Resistors Integrated circuits are normally laid out with little regard for future modification. The contact resistance Section 5.
The resistor divider formed by R3 and Scoep illustratesa tank connection that is better suited cuture matched resistor dividers Each tank connects to the positive end of its respective resistor.
The choice of resistor materials can have tremendous impact on circuit performance, so substitutions should not be made without careful consideration of the consequences. Reducing the scopee of trimpads saves die area and reduces the cost of the integrated circuit.
Use a strip of minimum-width poly-1 as the fuse, and place a opening in the protective overcoat over the fuse. Lasers are also used to sever metal and poly links.
NSD and PSD are relatively shallow diffusions that avalanche at relatively low voltages due to sidewall curvature. Metal resistors typically have values between 50mR and Resistors in this range are used for constructing current sense circuits and for ballasting large power bipolar transistors.
Additional voltage nonlinearities occur in lightly doped diffused resistors, especially base pinch resistors, due to modulation of the depletion regions around reverse-biased junctions.
Modern processes maintain sheet resistances within or 25 ,10 except for pinch resistors. Circular turns are less affected by this rounding, and their values are therefore easier to compute. The heterogeneous nature of polysilicon also futue its temperature coefficient of resistivity. These resistors do not require contacts since the thin-film material is deposited immediately prior to the uppermost layer of metallization.
The critical electric field intensity where this nonlinearity begins equals approximately 0. So here we propose an automatic wiper system that automatically switches ON on detecting rain and stops when rain stops. One of these components is an ideal resistor, while the remainder are parasitic components that represent the undesired but unavoidable interactions of the resistor with the rest of the die.
Both polysilicon and aluminum fuses are difficult to program after encapsulation. Nonlinearity, or voltage modulation, arises from several sources, including self-heating, high-field velocity saturation, and depletion region encroachment. NBL can also help minimize noise coupling between resistors occupying a common tank by providing a lowimpedance path from the tank to a clean supply node.
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. Intrinsic or lightly doped polysilicon can be doped with NSD and PSD implants to provide additional choices of sheet resistance.
Assume a width bias of 0.
Diffused resistors should not be made narrower 11 12 The variability figures used in this section represent the three-sigma limits of a Gaussian distribution. The drawn length Ld of a dogbone resistor is measured from contact to contact, and the drawn width Wd is measured across the body of the resistor.
The resistor therefore gains value. Small-grained poly films therefore exhibit higher resistivities than large-grained films. This information can be summarized as a set of design guidelines: The device has the same basic structure as a small NPN transistor. Keep metal a minimum of 2um away from the openings in opening in the protective overcoat. The sliding contact removes or adds a certain length to the wider segment.
Email Required, but never shown. This limitation can be circumvented by dividing the resistor into several sections, each contained in its own base region. This same divider functions properly if the resistors are segmented and placed in separate tanks so that each segment experiences the same tank modulation. As with other SI quantities, a system of prefixes allows this unit to be scaled upward or downward.
The effects of linewidth variation can be minimized by increasing the resistor width to several times minimum. Use a drawn resistor width of 8 u m and a width bias of 0. The act of programming a Zener is called zapping, so these Zeners are called zap Zeners, or Zener zaps. Many of these layouts use the circular turns illustrated in Figure 5. Trimming is usually performed during wafer-level testing, and it usually requires specialized test equipment and procedures.
Some processes allow active circuitry to reside underneath trim pads, in which case very little area is wasted. Most resistors have relatively large temperature coefficients, and even modest increases in temperature can cause significant resistance variations. For a theoretical analysis, see Runyan, et al.