100 Core Professional Terms for Switching Power Supplies
From lianglite • Electronics Classroom
This article summarizes 100 commonly used professional terms in the switching power supply industry, with definitions specific to switching power supply applications, for engineers to quickly reference, learn and apply. lianglite helps you master power supply expertise and improve design and component selection efficiency.
Absolute Maximum Ratings (Device) Exceeding these values will cause permanent device damage. They are non-continuous operating ratings and do not represent normal operating conditions.
Ae – Effective Cross-Sectional Area The equivalent cross-sectional area of a cylindrical core of the same material and magnetic properties, corresponding to a geometrically sized magnetic core.
Ambient Temperature
- The temperature of still air surrounding the power supply, measured at least 100 mm away from the unit.
- Per MIL‑STD‑810E: the unit under test is fully surrounded by air with temperature variation ≤ 2°C and gradient ≤ 1°C/m.
Ampere Turns (NI) The product of coil current and number of turns.
ATP – Acceptance Test Procedure
BABT British Telecommunications Approval Body, responsible for certification of communications equipment and laboratory accreditation in the UK.
Behavioral Model A model describing circuit modules using mathematical relationships; the highest-level simulation model.
BJT – Bipolar Junction Transistor
BOM – Bill of Materials
Boost Converter Basic topology: inductor stores energy when the switch is on, releases energy to the output when off; output voltage is higher than input.
Breadboard Prototype platform for initial circuit construction; structure may not match the final product.
BS – British Standard
BSI – British Standards Institution Responsible for developing product compliance standards.
Buck Converter Basic topology: input is pulsed by a switch and filtered by LC; output voltage is lower than input.
Buck-Boost Converter Same as flyback converter.
Burn-In Power-on aging test to reduce early failure rate and improve stability, which may include temperature/power cycling.
C1 – Core Constant Sum of the ratios of total magnetic path length to cross-sectional area of each segment.
CENELEC European Committee for Electrotechnical Standardization, developing unified electrical standards for the EU.
CE Marking Compliance mark indicating conformity with all relevant EU standards.
CFM – Cubic Feet per Minute Unit of airflow.
CISPR – International Special Committee on Radio Interference
Common Common reference point for multiple circuits; not equivalent to ground.
Constant Current Operating mode where output current automatically adjusts with load.
Constant Voltage Operating mode where output voltage automatically adjusts with load.
Convection Heat exchange between solid surfaces and still air.
- Natural convection: heat transfer via natural airflow.
- Forced convection: airflow driven by fans or mechanical means for cooling.
DC/DC Converter Power supply that converts DC input to DC output at a different voltage.
Cross Regulation Percentage change in one output voltage caused by load variation on another output in a multi-output supply.
Crowbar Overvoltage protection circuit that quickly creates a near-short circuit when overvoltage is detected, protecting downstream circuits.
CSA – Canadian Standards Association Responsible for safety testing and standard development for the Canadian market.
CSA 22.2 No.950 Equivalent to UL1950.
Cuk Converter Derived buck-boost topology capable of ultra-low output ripple.
Curie Temperature Critical temperature at which ferromagnetic material transitions to paramagnetic.
Current Mode Control Dual-loop control method for PWM regulation.
Maximum Rated Output Current Maximum load current the power supply is designed to deliver under specified conditions.
DEMKO – Danish Electrotechnical Committee
Derating Lowering operating parameters to improve reliability, e.g., reducing output power at high temperatures.
DF – Dissipation Factor
DHHS – Department of Health and Human Services (US)
Drift Variation in power supply output over time and temperature with fixed input, load and temperature.
ECO – Engineering Change Order
Efficiency Ratio of output power to input active power, expressed as a percentage, typically rated at full load, nominal input, and 25°C.
EMC – Electromagnetic Compatibility Ability of equipment to operate properly in its electromagnetic environment without interfering with other devices.
EMI – Electromagnetic Interference Conducted and radiated interference generated by the power supply.
EN – European Standard
ESL – Equivalent Series Inductance
ESR – Equivalent Series Resistance
EUT – Equipment Under Test
Faraday Shield Electrostatic shield between primary and secondary sides of a transformer to reduce common-mode noise coupling.
FCC – Federal Communications Commission (US)
Feed Forward Control technique that directly senses input voltage and adjusts duty cycle in advance.
FET – Field Effect Transistor
Magnetic Flux Density Magnetic flux per unit area perpendicular to the field, related to field strength and permeability.
Soldering Flux Material used during soldering to prevent oxidation and improve wettability.
Flyback Converter Isolated buck-boost topology: inductor stores energy when switch is on, transfers energy to secondary when off.
Foldback Current Limiting Overcurrent protection where output current decreases as overload increases, reducing device stress.
Forward Converter Isolated step-down topology that transfers energy directly to the secondary during switch conduction.
Fourier Analysis / Series Mathematical method decomposing periodic waveforms into sine and cosine components.
Full Bridge Converter Four-switch bridge structure driving a transformer, suitable for high-power applications.
GaAs – Gallium Arsenide Semiconductor material.
Grounding Classes
- Good Ground: ideal laboratory ground for testing medical equipment.
- Fixed Ground: industrial cabinet ground.
- Mobile Ground: ground for vehicle/rail equipment.
Half Bridge Converter Two switches plus two capacitors form bridge arms, lower cost alternative to full bridge.
HALT – Highly Accelerated Life Test
HASS – Highly Accelerated Stress Screening
Heat Sink Metal structure that dissipates heat from components.
Hiccup Mode Cyclic on-off operating mode triggered by fault conditions.
Hi-Pot Test – Hipotential Test Dielectric withstand test verifying insulation breakdown voltage compliance.
Hold-Up Time Duration output voltage remains within specification after input power loss.
Hot Plug-In Ability to connect or remove power without turning off the system and without damage.
IEC – International Electrotechnical Commission Develops international electronic standards.
IMQ – Italian Certification Body
Inrush Current Peak input current at power-on instant of the power supply.
Insulation Classes (IEC)
- Basic Insulation: basic protection against electric shock.
- Supplementary Insulation: independent additional insulation.
- Double Insulation: basic + supplementary.
- Reinforced Insulation: strengthened insulation equivalent to or better than double insulation.
Inverter Device converting DC input to AC output.
ISO – International Organization for Standardization
Isolation Voltage Maximum voltage that can be continuously applied between two isolated sections of a power supply.
Laplace Transform Mathematical tool for solving differential equations.
le – Effective Magnetic Path Length Equivalent magnetic path length of a given core.
Lifetime Operating duration during which the power supply maintains electrical performance and meets MTBF requirements.
Line Regulation Percentage change in output voltage with varying input voltage.
LISN – Line Impedance Stabilization Network Used for EMI testing.
Load Regulation Percentage change in output voltage as load varies from minimum to maximum.
MIL‑STD – Military Standard
Minimum Load Minimum output current required for the power supply to meet all specifications.
MOSFET – Metal-Oxide-Semiconductor Field-Effect Transistor
MTBF – Mean Time Between Failures
NEC – National Electrical Code (US)
Common Mode Noise Noise component referenced between line and ground.
Differential Mode Noise Noise component between two lines.
Off-Line SMPS Operates directly from rectified AC mains without a front-end mains-frequency transformer.
Output Impedance Ratio of output voltage variation to load current variation.
OVP – Overvoltage Protection
PARD – Periodic and Random Deviation Combined representation of ripple and noise.
PFC – Power Factor Correction
Programmable Power Supply Power supply with output adjustable via analog or digital signals.
Prototype First validation sample of a product.
PWM – Pulse Width Modulation Voltage regulation by adjusting pulse width.
Push-Pull Converter Center-tapped transformer with two switches operating alternately.
Radiation Heat transfer via infrared electromagnetic radiation from an object.
Rated Output Current Maximum load current the power supply is designed to deliver under specified conditions.
Recovery Time Time for output voltage to return to stable range after a load transient.
Redundancy Ability of a multi-power system to maintain normal operation after partial failure.
Regulation Ability of a power supply to maintain output despite input and load changes.
Reliability Ability of a power supply to maintain function under specified conditions and duration.
Output Voltage Setting Resolution Minimum step size for output voltage adjustment.
Resonant Converter Topology that transfers energy using a resonant tank.
Return Common reference terminal.
Reverse Voltage Protection Protection against input/output polarity reversal.
RFI – Radio Frequency Interference
Ripple and Noise Amplitude of AC component in output within a specified bandwidth, expressed in mV peak-to-peak or RMS.
Reflected Ripple Current AC current induced at the input by switching action.
Royer Converter Self-oscillating push-pull topology for low-cost low-power applications.
Secondary Side Output side of an isolated power supply.
Remote Sensing Using separate wires to sense voltage at the load, improving regulation accuracy.
Short Circuit Protection Current limiting during short circuit to prevent power supply damage.
Single Fault Condition Operating state where a protective measure has failed (as defined by IEC).
SMT – Surface Mount Technology
Snubber Protection circuit that suppresses voltage/current spikes and reduces dV/dt and dI/dt.
Soft Start Gradually rising output voltage at startup to protect power supply and load.
Long Term Stability Output voltage variation over time with other conditions constant.
Temperature Related Terms
- Ambient Temperature: temperature of objects surrounding the power supply.
- Temperature Coefficient: rate of output voltage change due to temperature.
- Inlet Air Temperature: temperature at cooling air intake.
- Operating Ambient Temperature: temperature range for stable power supply operation.
Transfer Function Mathematical expression describing the input-output relationship of a system.
Transient Recovery Time Time for output to return to specified range after a load step change.
TUV Authorized German testing and certification body.
UL – Underwriters Laboratories (US) Safety certification organization.
- UL94: flammability rating for plastics.
- UL1012: safety standard for power supplies.
- UL1262: standard for laboratory equipment.
- UL1950: safety for information technology equipment.
UPS – Uninterruptible Power Supply
VDE – Association of German Electrical Engineers Responsible for safety and EMC certification.
Warm-up Drift Initial output voltage variation from power-on to thermal equilibrium.
Warm-up Time Time required for the power supply to reach thermal stability, typically around 30 minutes.
Split Bobbin Winding Parallel winding of primary and secondary with isolation barriers to improve insulation performance.
X Capacitor EMI suppression capacitor connected across line and neutral; commonly Type X2, pulse withstand voltage ≤ 2.5 kV.
Y Capacitor Safety-rated capacitor connected between power lines and ground; commonly Type Y2, meeting basic/supplementary insulation requirements.
ZVS – Zero Voltage Switching Switch turns on at zero voltage, reducing switching loss and noise.
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