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Electronics Glossary – H

H Henry – the unit for inductance.
h Parameters The set of parameters for a two port device that relates the input voltage and current to the output current and voltage.
Half Bridge A dual, forward converter, using two power switches can also be called a half bridge. Power, which does not exceed the supply voltage, is delivered to the load only during half the input cycle. This design permits the use of a smaller transformer.
Half Bridge Converter Converter topology that typically operates as a forward converter but uses a bridge circuit, consisting of two switching transistors, to drive the transformer. Also see Bridge Converter.
Half-Wave Rectifier The process of converting alternating current into a unidirectional current, by removing or inverting that part of the wave laying on one side of the zero amplitude axis. There are two general types of retificitaion processes, half-wave and full-wave.
Hall effect The Hall effect occurs when a magnetic field is applied to a currentcarrying semiconductor chip; it creates a voltage perpendicular to both the direction of current and the magnetic field. This means that moving the magnetic field in relation to the chip can control the output of the chip. The effect is used to make switches and sensors.
Hall Effect Transducer A device that produces a voltage output dependent upon an applied DC voltage and an incident magnetic field. The magnitude of the output is a function of the field strength and the angle of incidence with the Hall device.
handshake A multistep connection routine. A verification by the central processing unit that a computer data terminal has correctly identified itself, and all systems are ready to initiate communication.
hard copy Any form of computer-produced printed document. Also, human-readable typewritten or printed characters produced on paper at the same time that information is being keyboarded in a coded machine language, as when punching cards or paper tape. Where point-of-sale purchases are processed by computer, the data would appear on the receipt form (hard copy) while also being transmitted to the computer for processing.
Hard Magnetic Material A ‘permanent’ magnet material that has an intrinsic coercivity generally greater than or equal to about 300 Oersteds.
Hardness A general term that correlates with strength, rigidity, and resistance to abrasion or penetration. Measured on Shore or Rockwell scales. See also Shore.
hardware (1) The shells, guide pins, locking springs, jackscrews, strain relief clamps, shields, mounting screws, and other devices which may be added to a connector to make it acceptable for a particular function. (2) The mechanical, magnetic, electrical, and electronic devices from which a computer is built.
Harmonic Content The degree of distortion in a signal due to the presence of harmonics.
Harmonics Energy at integral multiples of the frequency of the fundamental signal. Normally expressed as THD (Total Harmonic Distortion) but can be specified for harmonics of interest in either a percentage of or decibels below the power level of the fundamental frequency signal.
harness A wire assembly involving two or more wires that are prepared and ready for installation into a unit or system.
HDMI High-Definition Multimedia Interface is a compact audio/video interface for transmitting uncompressed digital data.
HDOP Horizontal DOP
HDSL High-bit-rate Digital Subscriber Line- Designed to be a cost-effective method of delivering T1/E1 line speeds over unconditioned copper cable, without the use of repeaters.
Headend The source end of a coaxial cable TV system. Often, the site for signal processing equipment essential to proper functioning of a cable system.
header The base or mounting plate of an electronic package to which chips and leads are attached.
Heat Aging A test that subjects components or materials to temperatures above normal operating values to evaluate changes in performance in order to predict service life. See also Accelerated Aging.
Heat Flux Flow rate of heat across or through a material, typically given in W/cm2
heat guns Heat producing devices used for softening, curing, drying, preheating, and welding of plastics, coatings, and compounds as well as shrinking of heat-shrinkable plastic tubing and plastic films.
heat resistant A copper or brass terminal nickel plated to withstand 650°F.
Heat Shock A test to determine the stability of a material by continuously exposing it to an extremely high temperature for a short period of time. The test was developed both to demonstrate that the material is crosslinked and to observe any problems in dripping, cracking, or flowing.
Heat Sink A structure that is mechanically attached to a device that generates heat, in order to lower the overall thermal impedance between the point source of the heat within the device and its cooler surroundings.
heat sink tab A mechanical tab on an integrated circuit package for attachment to a heat sink.
heat-shrinkable A type of plastic material that has been cross-linked. A term describing tubes, sleeves, caps, boots, films, or other forms of plastic which shrink to encapsulate, protect, or insulate connections, splices, terminations, and other configurations.
Heat-Shrinkable Material A polymeric material capable of being reduced in size when exposed to heat.
hecto A prefix that indicates a factor 102, abbreviated as “h”.
Henry H – The unit for inductance.
hermaphroditic connector A connector in which both mating members are exactly alike at their mating face.
hermaphroditic contact A contact design which mates with another contact of the same design.
hermetic Airtight, impervious to external influence, as in a hermetic package. Often used to describe metal-to-metal solder or weld sealed packages. In reality all materials are permeable, hence specifications define acceptable levels of hermeticity.
hermetic seal Hermetically sealed connectors are usually multiple contact connectors where the contacts are bonded to the connector by glass or other materials and permit a maximum leakage rate of gas through the connector of 1.0 micron ft/hr at one atmosphere pressure for special applications. Maximum leakage rates below 1.0 can be specified.
Hermeticity The extent to which a seal is hermetic.
hertz Term for cycles per second by international standard, adopted and now common in U.S. From the German physicist’s name, Heinrich R. Hertz. In use we find that 60 cycles/second (or 60 cps) becomes 60 hertz (or 60Hz).
Heterolithic Microwave Integrated Circuit” A microwave integrated circuit that consists of silicon and glass, typically known as an “HMIC”.” This technology was invented and patented by M/A-COM. An HMIC consists of pedestals of Si embedded in glass. The Si pedestals may act as conductive vias from the top of the die to the bottom of the die, or there may be diodes formed at the tops of the pedestals. Conductor can be deposited on top of the glass to form transmission lines or lumped elements, such as spiral inductors, baluns or MIM capacitors.
hexadecimal numbering system A numbering system with the base 16. The digits of the system are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, and F.
HFC hybrid fiber-coaxial
hi temp A terminal designed to withstand extremely high temperatures; usually made from nickel and/or nickel alloys. AMP STRATOTHERM* terminals and splices, rated at 1200°F, are excellent examples of “hi temp” product.
Hiccup Mode Operating mode triggered by an output fault condition (short-circuit)in which the converter cycles on and off the duty cycle of on time to off time maintains the interenal power dissipation at a safe level until the fault condition is corrected.
High Line Maximum value of input line voltage specified for normal converter operaton. Also see Low Line and Input Voltage Range.
High Pass Filter HPF – A reactive circuit that rejects signals whose frequencies are below the 3 dB point frequency and passes signals whose frequencies are above the 3 dB point frequency.
High Potential Test (Hi-Pot Test) Test used to determine whether a converter passes its miminum breakdown voltage specification. Also see Breakdown Voltage.
High Q Filters A filter circuit that exhibits a high Q factor. It is very frequency sensitive and filters out or allows to pass, only those frequencies within a narrow band.
high voltage Generally considered to be a wire or cable with an operating voltage of over 600 volts. Also called high tension.
high-density polyethylene Those polyethylenes whose density ranges about .94 to .96 and above. They are linked in longer chains, forming a more rigid resin material.
high-level logic Also HI level. In digital logic, the more positive of the two logic levels in a binary system. Normally, a high logic level is used to represent a binary 1 or true condition. See also low-level logic, negative logic, and positive logic.
high-speed socket A ceramic chip carrier socket for highpincount circuits of up to 164 contacts on .020in. centerlines. Highspeed refers to the short electrical length of the contacts.
Hi-Rel Screening Regimen of testing intended to induce latent infant mortality failures in a semiconductor lot in order to insure that the surviving devices will operate as predicted by mean-time-before-failure for the device type.
HMIC Heterolithic Microwave Integrated Circuit
Hold Current (1) The largest steady state current that, under specified ambient conditions, can be passed through a PolySwitch device without causing the device to trip. For SiBar devices, the current at which the device resets to a high-impedance state once the surge current dissipates. (2) The minimum current which will keep the contact springs in a relay energized. Also called the electrical hold value.
Hold Current Minimum The minimum current required to maintain the device in the on-state. For SiBar thyristors, the current at which the device resets to a high-impedance state once the surge current dissipates.
Hold Voltage The lowest voltage that can be applied without any change in state of the contacts from their energized position. This is just above the maximum drop-out voltage. Leakage Current The rms current conducted by the output circuit of the relay at maximum rated voltage with the contacts open.
holding strength Ability of a connector to remain assembled to a cable when under tension.
Hold-Up Time Period of time that a converter output remains operating within specification following the loss of input power. This is a more common specificatioin for AC/DC supplies.
Hole The term used to describe the conceptual positive charge carrier. A hole is actually a vacancy in the valance band of an otherwise electrically neutral atom, thereby resulting in a positive ion. The charge of a single hole is ( )1.6 * 10-19 coulombs.
hole conduction The apparent movement of a hole to the more negative terminal in a semiconductor. Since the hole is positive, this movement is equivalent to a flow of positive charges in that direction.
holes Holes can be made in the ceramic prior to or after firing. The post-firing process is relatively costly, but affords much greater accuracy of location than does the punching operation used on the green ceramic.
Hollerith A 12-bit code used for recording characters in punched cards.
hook tongue A terminal with a tongue that is open from the side rather than from the end.
Hookup Wire and Cable Wiring used to connect various points in electronic assemblies.
Horizontal cabling Includes the work area outlet, distribution cable and connecting hardware in the telecom closet.
hot melts Adhesives or other thermoplastic materials used for production bonding. A mechanical bond is formed when the material cools.
Hot Plug-In A common requriement in distributed power systems wherein the power board must be capable of being connected/disconnected from the power bus without damage. Power board components must be protected against the resultant high inrush currents.
Hot-Melt Adhesive An adhesive that becomes activated by heating. When heated, it melts, flows over the substrate surface, and forms an adhesive bond. Reheating causes the adhesive to remelt.
Hot-Plug The act of making a connection to the output port of a functioning peripheral or host. USB architecture is designed to recognize the connected function and ‘enable’ it by providing necessary power and loading all necessary drivers.
housing An insulating encapsulation for contacts. When pins or sockets are inserted into a housing, the assembly is usually referred to as a connector. Housing is sometimes referred to as “block.”
HPF High Pass Filter – A reactive circuit that rejects signals whose frequencies are below the 3 dB point frequency and passes signals whose frequencies are above the 3 dB point frequency.
Hub Class of USB equipment that attaches to the Host and provides additional USB output connections for other hubs or functions. May be classified as self-powered hubs or bus-and self-powered hubs.
Humidity Aging Test A test described in Raychem’s PS300 publication in which the resistance of a PolySwitch device at room temperature is measured before and after aging at an elevated temperature (e.g., 40¡C) and high humidity (e.g., 95% RH) for an extended time (e.g., 1000 hours).
Humidity Aging Test A test described in Raychem’s PS300 publication in which the resistance of a PolySwitch device at room temperature is measured before and after aging at an elevated temperature (e.g., 40¡C) and high humidity (e.g., 95% RH) for an extended time (e.g., 1000 hours).
hybrid A blend or composite of two different technologies. The context defines the technologies.
hybrid IC A composite of either monolithic integrated circuits, or discrete semiconductor device circuits, in a unit packaging configuration.
hygroscopic Capable of absorbing moisture from the air.
Hysteresis and Hysteresis Loss Hysteresis means to lag behind. This is the tendency of a magnetic material to retain its magnetization. Hysteresis causes the graph of magnetic flux density versus magnetizing force (B-H curve) to form a loop rather than a line. The area of the loop represents the difference between energy stored and energy released per unit of volume of material per cycle. This difference is called the hysteresis loss.
Hysteresis Loop A closed curve obtained for a material by plotting corresponding values of flux density for the ordinate and magnetizing force for the abscissa when the material is passing through a complete cycle between definite limits of either magnetizing force or flux density. If the material is not driven into saturation it is said to be on a minor loop.
Hz Hertz – A measure of frequency equal to one cycle per second.
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