MICROPOWER DIRECT Glossary Of Power Conversion Terms Alternating Voltage: A voltage that periodically switches direction of flow from positive to negative. — A — The average value of an AC voltage, for a pure sine Absolute Maximum Ratings: Peak perfor- wave, is zero. One cycle (or period) is the time it mance ratings for a power supply. If exceeded, takes the voltage to rise to its maximum value in one permanent damage to a power supply could direction, return to zero, rise to its maximum value in occur. When specified, these specifications are not the opposite direction and again, return to zero. The given as continuous ratings, and proper operation number of cycles per second is the AC frequency. is not implied. Ambient Air: The air mass immediately surround- AC: Abbreviation for alternating current. See Al- ing an operating power supply. Reliable operation ternating Current. of power supplies requires sufficient surrounding air AC/DC: Abbreviation for alternating current/ mass and flow to prevent thermal runaway caused direct current. by heat dissipated by the supply. AC Current: See Alternating Current. Ambient Temperature: The average tem- perature of air immediately surrounding a power AC Front-End: Part of a distributed power system. Temperature measurements should be system that will convert ac line voltage to a made about 0.5 inches from the body of the power semiregulated dc voltage level. An AC front-end supply. See Operating Temperature and Storage will typically provide power factor correction and Temperature. universal (~85 VAC to 265 VAC) ac compatibility. An ac front-end’s output voltage is usually 350 Ambient Temperature Range: The tempera- VDC to 400 VDC. See Power Factor Correction. ture range of air surrounding a power system over which it can be safely operated. Ambient tempera- AC Line: The ac power distribution lines. See ture ranges are often extended by using forced air Alternating Current. flow or power derating requirements. MicroPower Direct AC Line Filter: A filter placed in the ac line to American National Standards Institute: MPD, a leading worldwide provider of pow- condition high frequency noise variations. (ANSI) A US based organization that develops er conversion products, was founded by a AC Voltage: See Alternating Voltage. standards for prod- ucts, processes, and group of industry veterans in 1999. Located Accelerated Stress Testing: (AST) See Highly systems, etc. They in Stoughton, MA, we are committed to de- Accelerated Life Testing and Highly Accelerated also accredit stan- livering innovative, high quality power con- Stress Screening. dards developed by verters at the lowest possible prices. Active Current: The portion of an alternating other organizations. current that is in phase with the voltage. Active We currently off er over 5,000 low cost American Wire Gauge: (AWG) A standard current equals the average power divided by the standard “off -the-shelf” high performance for sizing wire by cross sectional area. AWG has effective voltage. See Average Power, Effective power converters. Our product lines include been used in North America since 1857, it is also Voltage, Reactive Current. DC/DC converters, AC/DC power supplies, known as the Brown & Sharpe wire gauge. The high brightness LED drivers, IGBT drivers Adjustment Range: The range limits over which cross-sectional area of each gauge is an important & controllers, and switching POL regulators. power system parameters may be varied. Typically factor for determining its current-carrying capacity. used with the output voltage of a power supply. Ampere Component selection and layout are care- Often called Trim Range. : (A) The base unit of current, equal to: fully considered at the design stage to op- E Aging: The operation of a power supply under I = timize product reliability. All manufacturing tightly controlled conditions (input voltage, output R is in ISO9000 registered factories under load, ambient temperature, etc.) for a predeter- Where: I = Current strict quality control system guidelines. All mined time. Aging is used in reliability testing to E = Voltage products are supported worldwide, and car- screen out or stabilize marginal units (infant mor- R = Resistance ry a standard three year warranty. tality). See Burn-in. Amplifier: See Error Amplifier. MPD power products have been designed Alternating Current: A periodic current that into a wide variety of products and sys- will symmetrically switch direction of flow from Anode: The “positive” terminal connection to a tems by a very diverse customer base. End positive to negative values. Over a set period of diode, LED etc. See Cathode. time, the average value of an AC current, for a products range from computer peripherals Apparent Power: The product of input rms volt- pure sine wave, is zero. The time period it takes age times input rms current. High rms values in AC to test instrumentation to telecommunica- the current to go from zero to maximum positive tions equipment to process/industrial con- input switch-mode power systems, where the input and back to zero (the positive alternation), then to current is distorted results in high apparent power. trols to medical devices and more. maximum negative and return to zero (the negative alternation) is one cycle. The number of cycles per Applied Voltage: The voltage presented to a second is the AC frequency. circuit point or system input, as opposed to the voltage drop resulting from current flow through applications. Low (or narrow) beam angle LEDs an element. are typically used in indicator applications Assembly: The complete power system, power where a higher luminous intensity is required supply or power converter that is fabricated from (for improved visibility). Also called View Angle, subassemblies and/or various components. Viewing Angle or Beam Spread. Beam Lumens Asymptotic Breakdown Voltage: A voltage : The total lumens contained level, that if applied over a long period of time, within a light beam. will break down insulation. Beam Spread: See Beam Angle. Attenuation: Attenuation typically refers to the Benchmark: A performance standard. Used in loss of power over a length of cable (or board Figure 1 Simplifi ed Balun Filter product, system or component testing. trace), when used regarding power systems. is operating, it reduces the voltage and regulates the Bench Power Supply: A cased power supply Automatic Test Equipment: (ATE) Equipment current to the circuit. This protects the lamp from with displays and controls that are used to precisely (typically a combination of hardware & software) burning out, and the resultant regulated current adjust operating characteristics. Usually an ac used to test/stress power conversion products output produces a steady light output input device, bench supplies are sometimes called or systems. Balun Filter: An input line filter that include a Laboratory Supplies. Autoranging Input: An ac power supply input differential wound transformer often used within Binning: LEDs are sorted as part of the manufac- circuit that senses the input voltage level and au- power supplies. They show high impedance to turing process. Binning helps minimize operating tomatically switches the input to the appropriate common mode signals and low impedance to tolerances in customer shipments. Sort criteria range (i.e. 90 VAC to 130 VAC or 180 VAC to 264 differential mode signals. Also called a Common might include intensity, color, forward voltage, etc. Mode Filter. VAC). Sometimes called an Auto Select Input. Bipolar Junction Transistor:: (BJT) A three Auxiliary Output: A secondary output that is Barrier Strip: A connector that includes a pro- layer, three terminal component whose construc- used to supply low power levels to housekeeping tective barrier between adjacent terminals. Often tion consists of two PN junctions. The two basic circuits etc. It operates separately from the main used on moderate/ high power AC power supplies types are PNP or NPN (which refers to the arrange- output of the supply. or on applications where a wiring harness is used. ment of the N & P type material used). The bipolar transistor acts as a current controlled switch. Average Current:: (IAVG) The average value Baseplate: A metal plate or substrate to which of current flowing in an ac circuit. For a perfect circuit components are mounted or the power Birmingham Wire Gauge: (BWG) A standard sine wave, the value would be zero. The value of supply is attached. It is used to draw heat away used for sizing wire. BWG diameters are larger average current is equal to 0.637 times the value from critical circuit components and (sometimes) than corresponding AWG diameters (for a given of peak current. to provide mechanical stability. See Heat Sink. wire size). Sometimes called the Stubs Gauge. AVG Pk Baseplate Temperature: See Case Tem- I = 0.637 I Bleeder: See Bleeder Resistor. perature. Average Power: (PAVG) In an ac circuit, the Bleeder Resistor: A resistor that provides a average value of ac power. For resistive circuits, Basic Insulation: The level of insulation required path for current drain. Often used in filter circuits it equals the square of the rms current times the for the proper operation of a power system or to provide a discharge path for capacitors. In circuit resistance, as given by: component and for a minimum level of protection high-voltage power supplies, they can serve as a against electrical shock. It is sometimes called safety circuit. Also called a Drain Resister. PAVG = (Irms)2R Functional Insulation. See also Insulation, Bleeder Power: The power dissipated (as heat) Where: Irms = rms value of the circuit current Double Insulation, Reinforced Insulation and across a bleeder resistor. R = Circuit resistance in ohms Supplementary Insulation. Block Diagram: A simplified diagram of an elec- Average Rectified Current: The average Battery: A multi-cell device that produces DC elec- tronic circuit or system. The different components or value of current from a full-wave rectifier circuit prior tricity via an electrochemical action.