|
| AC |
alternating current |
| ADE |
application development environment—A software environment incorporating the development, debug, and analysis tools for software development. |
| admittance |
The reciprocal of impedance. |
| aperture time | The period during which the ADC is reading the input signal. |
| ATE | automated test equipment—A term typically applied to computer-based systems for testing semiconductor components or circuit card assemblies. |
| auxiliary power | Power drawn from a separate, external power source. Use an auxiliary power source to increase the output capability of a power supply that is only drawing internal power. |
| AWG | American Wire Gauge—A U.S. standard set of non-ferrous wire conductor sizes. Gauge means the diameter. Non-ferrous includes copper and also aluminum and other materials, but is most frequently applied to copper household electrical wiring and telephone wiring. Typical household wiring is AWG number 12 or 14. Telephone wire is usually 22, 24, or 26. The higher the gauge number, the smaller the diameter and the thinner the wire. Since thicker wire carries more current because it has less electrical resistance over a given length, thicker wire is better for longer distances. |
|
| bandwidth |
The range of frequencies present in a signal, or the range of frequencies to which a measuring device can respond. |
| bipolar |
A signal range that includes both positive and negative values (for example, -5 V to +5 V). |
|
| calibration |
The process of determining the accuracy of an instrument. In a formal sense, calibration establishes the relationship of an instrument's measurement to the value provided by a standard. When that relationship is known, the instrument can then be adjusted (calibrated) for best accuracy. |
| capacitance |
The ability of a capacitor to store an electrical charge, measured in Farads. |
| common-mode noise |
Noise present between the output common/ground and the chassis or earth ground. In this sense, the equivalent circuit is a current noise source connected across these two terminals. |
| compliance |
A channel that is operating at the programmed limit because the requested level cannot be reached.
|
| connector |
A device that provides electrical connection. |
| constant current mode |
An NI-DCPower control mode in which a circuit supplies a constant current source, independent of the load placed on the current generator. When constant current mode is enabled on an output channel, the current is held constant at the value specified by the current limit, and the voltage rises or falls as the load requires more or less power. |
| constant voltage mode |
An NI-DCPower control mode in which a circuit supplies a constant voltage source. When constant voltage mode is enabled on an output channel, the voltage is held constant at the value specified by the voltage level despite load changes. |
| crowbar protection |
A method of overvoltage protection that shunts the auxiliary power input to ground if excessive voltage is detected. When crowbar protection is enabled, a overvoltage condition might cause the auxiliary power input fuse to blow. |
| current |
The rate of flow of electric charge, measured in amperes. |
| current leakage |
Error current that travels through undesired paths and can degrade signals. |
| current-resistance loss |
See voltage drop. |
|
| DC |
direct current |
| DC voltage |
The direct current (non-changing) component of a voltage. In practice, the DC voltage should not change over the period of observation, that is, the measurement time. |
| Delayed Configuration mode |
An NI-DCPower configuration mode in which every configuration call is cached until the configuration is initiated. |
| DMM |
digital multimeter |
| driver |
Software that controls a specific hardware device such as a DAQ device or GPIB interface device. |
| DSP |
digital signal processor |
| DUT |
device under test |
|
| electrical load |
A device to which power is supplied. |
| EEPROM |
Electrically erasable programmable read-only memory. Read-only memory that you can erase with an electrical signal and reprogram. |
| EMF |
electromotive force |
| EXTCLK |
Auxiliary Clock signal. |
|
| fall time |
The time for a signal to move from 90% to 10% of the signal value. |
| frequency |
f—The basic unit of rate, measured in events or oscillations per second using a frequency counter or spectrum analyzer. Frequency is the reciprocal of the period of a signal. |
|
| GND |
ground—A noncurrent-carrying circuit intended for safety. |
|
| handle |
A unique variable you use to refer to a window or other interface element in C programming. |
| Hz |
hertz. Cycles per second. See frequency |
|
| Immediate mode |
An NI-DCPower configuration mode in which every configuration call is immediately applied to the device. |
| impedance |
The property of a circuit or circuit element to resist both steady-state current flow (resistance) and changes in current or voltage (reactance). |
| inductance |
The property of a circuit or circuit element to oppose a change in current flow, thus causing current changes to lag behind voltage changes. Inductance is measured in henrys (H). |
| inductive load |
A load whose current changes lag behind its voltage changes. See inductance. |
| instrument driver |
A set of high-level functions that control and communicate with instrument hardware in a system. |
| internal power |
For NI DC power supplies, power drawn from the PXI chassis backplane. |
| inverse voltage protection |
A protection circuit that prevents the power supply from being damaged in the event that an inverse voltage is applied at the input or output terminals. |
| I/O |
input/output |
| isolation |
Describes the electrical separation between the input and the output, measured in resistance. |
| isolated output |
An output that is electrically separated from the input. |
| IVI |
Interchangeable Virtual Instruments. A software standard for creating a common interface (API) to common test and measurement instruments. |
| IVI driver |
A driver written according to the IVI specification. The generic driver for a class of instruments (such as voltmeters) is called a class driver, whereas the driver for a specific instrument from a specific manufacturer is called a device-specific driver. |
|
| LabVIEW |
Laboratory Virtual Instrument Engineering Workbench. LabVIEW is a graphical programming language that uses icons instead of lines of text to create programs. |
| leakage current |
Error current that travels through undesired paths that can degrade signals. |
| LED |
light emitting diode—A semiconductor light source. |
| line regulation |
The ability of the power supply to maintain its output voltage given changes in the input line voltage. Line regulation is expressed as percent of change in the output voltage relative to the change in the input line voltage. For NI DC power supplies, the line regulation specification refers to the auxiliary power input.
|
| load |
See electrical load. |
| load regulation |
The ability of an output channel to remain constant given changes in the load. The control mode enabled on the output channel determines the way in which load regulation is expressed. |
|
| max |
maximum |
| Measurement & Automation Explorer |
The standard National Instruments hardware configuration and diagnostic environment on Windows. |
| min |
minutes or minimum |
|
| NaN |
Not a Number—Digital display value for a floating-point representation of <Not A Number>. Typically the result of an undefined operation, such as log(–1). |
| noise |
Analog. Unwanted signals. Noise comes from both external and internal sources. Noise corrupts signals you are trying to send or receive. |
| normal-mode noise |
Noise present between the output HI and output LO/ground, appearing either in series (constant voltage mode) or parallel (constant current mode) with the output. Normal-mode noise can be expressed as voltage noise or current noise, depending on the control mode of the output channel. |
|
| output HI |
The output channel terminal capable of supplying a DC potential. |
| output LO |
The output channel terminal referenced to circuit common. |
| overcurrent protection |
A power supply protection circuit that limits the output current in the event of an overcurrent condition. |
| overvoltage protection |
A power supply protection circuit that either shuts down or crowbars the power supply in the event of an overvoltage condition. |
| OVP |
overvoltage protection |
|
| ppm |
parts per million |
| preload |
A small amount of current drawn from a power supply used stabilize its operation. |
| programmable power supply |
An instrument providing user-adjustable power (voltage and current) for a DUT. |
| pulse load |
A load whose current amplitude deviates from its steady state value for short periods of time. |
| PXI |
PCI eXtensions for Instrumentation. A modular, computer-based instrumentation platform. |
|
| reactance |
The property of a circuit or circuit element to resist changes in voltage or current. |
| remote sensing |
A method of monitoring the output voltage directly at the load rather than at the power supply output terminals. Remote sensing improves regulation when in voltage mode. |
| resistance |
The property of a material to resist or inhibit current flow. |
| resonance |
The frequency at which capacitive reactance and inductive reactance are equal and, thus, cancel one another's effects. |
| response time |
The time a device takes to respond to a request. |
| ringing |
A decaying sinusoidal signal resulting from an external perturbation (for example, a transient load, an application of a capacitive discharge, etc). |
| ripple |
The level of the undesired frequency components on a DC power supply output. The ripple is most often the same frequency as the AC input voltage or the internal switching frequency. This is measured using a spectrum analysis. |
| rise time |
The time for a signal to transition from 10% to 90% of the maximum signal amplitude. |
| rms |
root mean square |
|
| settling time |
The time required for a circuit to reach a stable mode of operation. |
| shunt |
An electronic component that diverts current. |
| shunt resistance |
A resistor connected in parallel or in shunt with a circuit or other component. |
| sink |
A device that can dissipate power. |
| sinking |
The ability to dissipate power from active circuitry. |
| sinusoidal signal |
A signal varying in proportion to the sine of an angle or time function. |
| slew rate |
The voltage rate of change as a function of time. Slew rate limitations are first seen as distortion at higher signal frequencies. |
| SMU |
source-measure unit. A device capable of sourcing and measuring DC voltage and current with high precision. |
| source |
A device that can supply power to an external device. |
| sourcing |
The ability to supply power for external circuitry. |
|
| tempco |
temperature coefficient. Describes how much a property changes with temperature. |
| thermal protection |
A power supply protection circuit that shuts down the power supply in the event of an overtemperature condition. |
| thermistor |
Semiconductor sensor that exhibits a repeatable change in electrical resistance as a function of temperature; most thermistors exhibit a negative temperature coefficient. |
| time constant |
A figure of merit for system speed. |
| transient response |
The length of time it takes for a circuit to recover from a sudden change in an output load or an input voltage. |
|
| uncertainty |
The total calculated error caused by calibration error, noise, nonlinearity, offsets, temperature drift, and so on. |
| unregulated mode |
Describes the state of an output channel that has neither constant voltage mode or constant current mode enabled. |
|
| V |
Volts. |
| VAC |
Volts, Alternating Current. |
| VDC |
Volts, Direct Current. |
| VI |
Virtual Instrument—Program in LabVIEW that models the appearance and function of a physical instrument. |
| voltage drop |
The decrease in voltage along a conductor. The amount of voltage drop is dependant on the conductor (wire gauge and length) and the amount of current flowing through the conductor. |
| VXI |
VME eXtensions for Instrumentation (bus) |
| VXIplug&play SystemsAlliance |
A group of VXI developers dedicated to making VXI devices as easy to use as possible, primarily by simplifying software development. |
|
| wideband noise |
The maximum amount of microprocessor and power supply noise that may be present on the output voltage. |