|PA||Power amplifier: An amplifier used to drive significant power levels. An audio amplifier that drives a loudspeaker and the final stage of a transmitter are common examples.|
|PAL||Phase alternate line: A television standard used in most of Europe. Similar to NTSC, but uses subcarrier phase alternation to reduce the sensitivity to phase errors that would be displayed as color errors. Commonly used with 626-line, 50Hz scanning systems, with a subcarrier frequency of 4.43362MHz.
See: Video Basics
|PAM||See Pulse-Amplitude Modulation|
|Parallel||See Parallel Interface|
|Parallel Interface||A parallel interface (as distinguished from a serial interface) is one in which data is sent on several wires (or several wireless channels) at once. Examples: GPIB, byte-wide parallel interfaces to data converters, memory and data buses on computer boards and backplanes.
In contrast, a serial interface uses one wire or wire-pair or wireless channel (or one in each direction).
|Parasite Power||The device derives its supply power directly from the serial interface (1-Wire).|
|Part 18||See ISM|
|Partition Locking||The ability to lockout writes and/or reads to certain sections of the memory.|
|Passive Optical Network||See PON|
|PBC||Port bypass circuit|
|pC||1. pC: Picocoulomb(s), a unit of electrical charge.
2. PC: Printed circuit (see: Printed Circuit Board).
3. PC: Personal Computer.
|PC Board||See Printed Circuit Board|
|PC Card||Add-in cards that conform to the PC Card specification (formerly called PCMCIA). A PC Card is a removable device, approximately the size of a credit card, designed to plug into a matching slot.|
|PCB||See Printed Circuit Board|
|PCI||Peripheral Component Interconnect: A standard interface used primarily on computer backplanes to connect interface cards and peripheral devices to the processor bus. PCI is often used for video display cards, network interfaces (e.g. Ethernet), and peripheral interfaces such as SCSI or USB.
PCI buses typically also support the older Industry Standard Architecture (ISA) standard.
|PCI Express||PCI Express® (Peripheral Component Interconnect Express), officially abbreviated as PCIe®, is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP standards. It is used to link motherboard-mounted peripherals and as an expansion card interface for add-in boards.
The PCIe electrical interface is also used in a variety of other standards, most notably the ExpressCard laptop expansion card interface.
|PCI-E||See PCI Express|
|PCIe||See PCI Express|
|PCM||Pulse-Code Modulation (PCM) is the conversion of an analog signal (e.g. audio) into digital, binary (0 or 1), coded pulses, decreasing noise susceptibility. PAM, PFM and PWM are examples of PCM methods.|
|PCMCIA||Personal Computer Memory Card International Association: A standard for miniaturized laptop expansion cards for modems, storage, and other devices. The standard was officially renamed "PC card."|
|PCS||Personal Communications Service: An American generic term for a mass-market mobile phone service, emphasizing personal communication, independent of the technology used to provide it. PCS includes such digital cellular technologies as GSM 1900, CDMA and TDMA IS-136. 2G, CDMA, Digital, GSM, TDMA.|
|PCT||See Pressure Cooker Test|
|PDA||Personal digital assistant. See: "PDA Solutions."|
|PDC||Personal Digital Cellular: The digital wireless standard used in Japan. PDC uses TDMA air interface.|
|PDH||See Plesiochronous Digital Hierarchy|
|PDM||Pulse density modulation|
|Peak Inverse Voltage||Peak Inverse Voltage (PIV) or Peak Reverse Voltage (PRV) refer to the maximum voltage a diode or other device can withstand in the reverse-biased direction before breakdown. Also may be called Reverse Breakdown Voltage.
Note that PIV is also an abbreviation for FIPS 201 Personal Identity Verification.
|peak reverse voltage||See Peak Inverse Voltage|
|PECL||Positive-referenced emitter-coupled logic|
|Peltier Junction||See TEC|
|Periodic Operating Point Analysis||See POP Analysis|
|Peripheral Component Interconnect||See PCI|
|Personal Communications Service||See PCS|
|Personal Digital Cellular||See PDC|
|pF||Picofarad. A Farad is the unit of capacitance. A pF is 10-12 of a Farad. (1000pF = 1nF, 1000nF = 1 microfarad).|
|PFM||Pulse-Frequency Modulation: A pulse modulation technique in which the frequency is varied with the input signal amplitude. The duty cycle of the modulated signal does not change. Because it is always a square wave with changing frequency, PFM is also referred to as square-wave FM.|
|PFMEA||Process Failure Mode and Effects Analysis (PFMEA): A methodology for assessing the weaknesses of production processes and the potential effects of process failures on the product being produced.|
|PG||Power-good; power gain|
|PGA||Programmable Gain Amplifier: An amplifier whose gain can be varied by a separate input (usually a digital value).|
|Phase alternate line||See PAL|
|Phase Jitter||See Jitter|
|Phase-shift keying||See PSK|
|Pin Electronics||Electronic circuitry in an automated tester (ATE system) that connects to the device under test.
Pin electronics can deliver signals, power, or precise voltages and currents, and can measure the pin's response, drive, and electrical characteristics.
|PIV||See Peak Inverse Voltage|
|PKI||Public Key Infrastructure: A combination of standards, protocols, and software that creates, edits, and revokes digital public key certificates.|
|PLA||Programmable logic array|
|Plastic Leaded Chip Carrier||See PLCC|
|PLC||A Programmable Logic Controller (PLC, or Programmable Controller) is a ruggedized, microprocessor-based system which provides factory or plant automation by monitoring sensors and controlling actuators in real time.
See: Maxim Solutions for PLCs.
PLC is also used as an acronym for Powerline Communications (HomePlug).
|PLCC||Leaded Chip Carrier, also called PLCC or Plastic Leaded Chip Carrier: A square surface mount chip package in plastic with leads (pins) on all four sides. Example: Maxim 20-pin LCC diagram (PDF)|
|Plesiochronous Digital Hierarchy||The time-division multiplexed network used by telecommunications companies to transport phone calls and data over copper cabling. The entire network shares a common frequency throughout it's tree-like structure, although phase and time delay variations exists at various points along the edge of the network.|
|PLL||A phase-locked loop (PLL, or phase lock loop) is a control system that generates a signal that has a fixed relation to the phase of a "reference" signal. A phase-locked loop circuit responds to both the frequency and the phase of the input signals, automatically raising or lowering the frequency of a controlled oscillator until it is matched to the reference in both frequency and phase.
Phase-locked loops are widely used in radio, telecommunications, computers and other electronic applications. They may generate stable frequencies, recover a signal from a noisy communication channel, or distribute clock timing pulses in digital logic designs such as microprocessors.
|PLM||Pad limiting metal|
|PMIC||Power Management Integrated Circuit: Circuits used to regulate and control power.|
Pmods™ are small I/O interface boards used to extend the capabilities of FPGA/CPLD and embedded control boards. Pmods communicate with system boards using 6- or 12-pin connectors.
Pmod is the trademark of Digilent Inc.
|pMOS||A p-channel metal-oxide semiconductor (pMOS) transistor is one in which p-type dopants are used in the gate region (the "channel"). A negative voltage on the gate turns the device on.|
|PMR||Private Mobile Radio: Radio bands generally for use within a defined user group, such as the emergency services or by the employees of a mining project.|
|PN Temperature Sensor||See Junction Diode Sensor|
|PoE||Power-over-Ethernet: A means for delivering power to a remote device using the same cable lines used to deliver Ethernet data.|
|point of load||See Point-of-Load|
|Point-of-Load||Point-of-load (POL) power supplies solve the challenge of high
peak current demands and low noise margins, required by high-performance semiconductors such as microcontrollers or ASICs, by placing individual power supply regulators (linear or DC-DC) close to their point of use.
|poly-carbonmonofluoride||See Lithium batteries|
|PON||Passive optical network: A cost-effective way to provide high performance Fiber to the Home (FTTH) connectivity via shared optical fiber. PON connects up to 32 (or more) homes on the same network using passive optical components (splitters).|
Periodic Operating Point (POP) Analysis is a simulation technique (used by EE-Sim) to find the steady state operation condition of a switching power supply design.
One conversion cycle is run in the time domain. The inductor currents and capacitor voltages at the beginning of that cycle are compared to the inductor currents and capacitor voltages at the end of that cycle. When the difference has been driven below 10-9, the steady state conditions are identified and POP Anaylsis ends.
|Pop Reduction||See Click/Pop Reduction|
|Positive Temperature Coefficient||See PTC|
|Potentiometer||Variable resistor in which a wiper sweeps from one end of the resistive element to the other, resulting in resistance that is proportional to the wiper's position.|
|Power Added Efficiency||In an RF power amplifier, power added efficiency (PAE) is defined as the ratio of the difference of the output and input signal power to the DC power consumed. In other words:
PAE = (PRFOUT - PRFIN)/PDC = (PRFOUT - PRFIN)/(VDC*IDC)
|Power Amplifier||See PA|
|Power Fail||A feature in a microprocessor supervisory circuit that provides early warning to the microprocessor of imminent power failure.|
|Power Fail Comparator||See Power Fail|
|Power Fail Detector||See Power Fail|
|Power Harvesting||See Energy Harvesting|
|Power Management Integrated Circuit||See PMIC|
|Power Supply Rejection Ratio||See PSRR|
|Power-Fail Comparator||See Power Fail|
|PowerCap||A special surface-mount package with access to the internal cavity via an openable top. This packaging scheme allows easy upgrade of NV RAMs without having to change the PCB hardware layout. The user can simply open the lid and swap out the IC.|
|Powerline Communications||See HomePlug|
|PPAP||Production Part Approval Process. Used by automotive industry for acceptance of new products for release and use on automobiles.|
|PPOT||See Pressure Cooker Test|
|PRBS||Pseudorandom binary (bit) sequence|
|PRC||Parasitic resistance cancellation|
|PRCM||Parasitic resistance cancellation mode|
|Pre-Bias Soft Start||A power-supply feature that prevents discharging of the output capacitor when the power supply starts up. Discharging the output capacitor could create either start up oscillation problems at cold start or large voltage disturbances on the output voltage bus at hot plug-in. Pre-bias soft start is an important feature in redundant power-supply systems, parallel power supply modules, battery back-up voltage buses, and other applications where multiple power sources supply one node.
See the application note: MAX1917 Provides Pre-Bias Soft Start for Redundant Supply
|Preemphasis||In some transmission and recording systems (e.g. vinyl records, FM radio, analog magnetic tape), there is more noise at higher frequencies. To offset this, the audio signal is "preemphasized" at the transmitter -- filtered with a high-pass filter to boost the higher audio frequencies. A matching low-pass filter is used at the receiver to return to an overall flat audio-frequency response. The filter at the receiver reduces the high-frequency noise introduced by the transmission process.|
|Pressure Cooker Test||A Pressure Cooker Test (PCT) tests a part under high temperature, humidity, and pressure conditions. Also called an Autoclave Test or Pressure Pot Test (PPOT).|
|Pressure Pot Test||See Pressure Cooker Test|
|Printed Circuit Board||A printed circuit board, or PC board, or PCB, is a non-conductive material with conductive lines printed or etched. Electronic components are mounted on the board and the traces connect the components together to form a working circuit or assembly.
A PC board can have conductors on one side or two sides and can be multi-layer — a sandwich with many layers of conductors, each separated by insulating layers.
The most common circuit boards are made of plastic or glass-fiber and resin composites and use copper traces, but a wide variety of other materials may be used. Most PCBs are flat and rigid but flexible substrates can allow boards to fit in convoluted spaces.
Components are mounted via SMD (surface-mount) or through-hole methods.
|Private Mobile Radio||See PMR|
|PRM||Performance report message|
|Process Failure Mode and Effects Analysis||See PFMEA|
|PROCHOT#||Digital output pin on Intel's Pentium 4 processors that indicates the internal Thermal Control Circuit has activated. This occurs when the processor has reached its maximum safe operating temperature.|
|Production Part Approval Process||See PPAP|
|PROFIBUS||Vendor-independent open fieldbus standard used in manufacturing, building automation, and process control. Utilizes a nonpowered two-wire (RS-485) network. PROFIBUS is standardized under the European Fieldbus Standard EN 50 170. It includes three versions: FMS, DP, and PA. Visit www.profibus.com for more information.|
|Programmable Controller||See PLC|
|Programmable Gain Amplifier||See PGA|
|Programmable Logic Controller||See PLC|
|PROM||Programmable read-only memory|
|PRT||Platinum Resistance Thermometer, a resistance temperature device (RTD).|
|PRV||See Peak Inverse Voltage|
|PSK||Phase-shift keying (PSK): A modulation technique in which the phase of the carrier conveys the input signal's information.|
|PSRR||Power Supply Rejection Ratio (PSRR) is the ability of an amplifier to maintain its output voltage as its DC power-supply voltage is varied.
PSRR = (change in Vcc)/(change in Vout)
See also: Ripple rejection, which is degree of immunity from AC in the power supply.
|PSW||Program status word|
|PTC||Positive Temperature Coefficient (PTC): When the resistance of a component rises with temperature, it is said to have a positive temperature coefficient.
Example: Hewlett-Packard's first commercial product, an audio oscillator, used a common light bulb as a PTC element in the feedback circuit to maintain constant output amplitude regardless of frequency.
|Public Key Infrastructure||See PKI|
|Pulse Code Modulation||See PCM|
|Pulse-Amplitude Modulation||Pulse-Amplitude Modulation (PAM) is a pulse modulation technique in which the amplitude of the pulse is varied with the input signal amplitude.|
|Pulse-Frequency Modulation||See PFM|
|Push-Pull||An output structure which uses one active device to source current and a second device to sink current. Common examples are: a CMOS stage in which an n-channel device pulls toward ground or a negative supply and a p-channel device pushes current to bring the output up; an output stage in an audio amplifier with an NPN and PNP device in totem-pole configuration.
See application note 660, "Regulator topologies for battery-powered systems."
|PVR||Personal video recorder|
|PWM||1. A method for using pulse width to encode or modulate a signal. The width of each pulse is a function of the amplitude of the signal.
2. A technique used to modulate the power delivered to a load.
In DC-DC switching regulators, the pulse width driving the main power switch (and hence, the duty cycle) is varied to maintain the desired output voltage. In DC motor-control applications, pulse width is used to vary motor speed.
|PWM Fan Control||See Fan Controller - PWM|
|PWM Temperature Sensor||Temperature sensor with digital, logic-level output. The output has a fixed frequency and the duty cycle varies with the measured temperature.|