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Power Supplies A to Z : "H"

We've included this handy glossary to help with the terminology & abbreviations relating to power products. Pick a letter below to begin.

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H

Abbreviation for henry, Magnetic Field Strength, or Magnetomotive Force.

Half Brick

Industry standard footprint for dc-dc converters. Dimensions are 61mm x 57.9mm (2.4in x 2.28in). See also Full Brick, Quarter Brick, Eighth Brick, Sixteenth Brick. Lambda's PAH range of dc/dc converters are examples of half bricks.

Half-Wave Rectifier

A component, such as a diode, that rectifies only one-half of the input ac wave to produce a varying/pulsing dc output. Compare with Bridge-Rectifier.

Half-Wave Rectifier

HALT

Acronym for Highly Accelerated Life Testing.

HASS

Acronym for Highly Accelerated Stress Screening.

HBC

Abbreviation of High Breaking Capacity.

Headroom

The difference between the Bulk voltage and the output voltage in a linear regulator.

Hecto

SI prefix multiplier. Multiplies by 102=100. So 100 hHz = 100 x 10² Hz = 10000Hz. Written as 'hecto'. Abbreviated to 'h'.

Henry (H)

Unit of measurement of Inductance. Written as 'henry'. Abbreviated to H.

Hertz (Hz)

The SI unit of measurement for Frequency, named in honour of Heinrich Hertz who discovered radio waves. One hertz equals one cycle per second. Written 'hertz'.

Hiccup Current Limit

When the output of a power supply exceeds certain limits, the control circuit will turn off the output, wait a period and then turn on the output once more. If the output current is still too high, this cycle is repeated until the power supply is turned off ot the fault condition is removed.

High Breaking Capacity (HBC)

A term relating to fuses which describes the level of current which the fuse will safely interrupt. This is usually 1500A minimum. Usual construction is a ceramic tube, filled with sand through which the fusible wire passes.

High Line

Highest specified input operating voltage.

Highly Accelerated Life Testing

A process developed to uncover design defects and weaknesses in electronic and mechanical assemblies using a selection of parameters to stress the product (including vibration, temperature changes, ac input level, etc.). It is a technique that addresses reliability issues at an early stage in product development, offering significant advantages over more traditional techniques.

Highly Accelerated Stress Screening

Used as part of the production process to detect component and HALT are used (such as rapid temperature cycling, power cycling, vibration, etc.), but once the product parameters are known from the HALT process, testing in production is usually at lower levels so that product life is not manufacturing irregularities as early as possible. Similar stress parameters to reduced.

Hi-Pot Test (High Potential Test)

A safety critical test performed by applying a high voltage for a specified time to two isolated points to determine adequacy of insulating materials.

Holding Time

See Holdup Time.

Holdup Time

The time, under worst case conditions, during which a power supply’s output voltage remains within specified limits following the loss or removal of input power. Sometimes called Holding Time.

 

HP

Unit of width (usually) in a 19 inch rack. 1 HP = 0.2 inches = 5.08mm. Same as TE.

Hybrid

The combination of different component technologies on a single substrate.

Hybrid Supplies

A power supply (PSU) that combines two or more different regulation techniques, such as switching and linear, or one that takes advantage of hybrid technology. See also Hybrid.

Hysteresis

1) The property of a magnetic substance that causes magnetisation to lag behind the force that produces it.

2) A variable voltage threshold determined by the logic state of the output of the circuit.

Hysteresis Loop

A curve that shows the values of the magnetic flux density in a cyclically magnetised material: one when the magnetising force is increasing, the other when it is decreasing. See Remanence, Coercivity.

Hysteresis Loop

Hysteresis Loss

Energy dissipated due to molecular friction as domains move through cycles of magnetisation.

Hz

Abbreviation for hertz.

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