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Glossary Terms and Definitions Beginning with the Letter P

0-9

p-channel	See pMOS
P-P	Peak-to-peak
pA	Picoampere(s)
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.
PAE	See Power Added Efficiency
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, link below). 3. PC: Personal Computer.
PC Board	See Printed Circuit Board
PC Card	See PCMCIA
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. Source: Wikipedia
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	See 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.
PDI	Phase-detector input
PDIP	Plastic dual-inline package
PDJ	Pattern-dependent jitter
PDM	Pulse density modulation
PDO	Phase-detector output
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
Peripheral Component Interconnect	See PCI
Peritel	See SCART
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).
PFD	Phase/frequency detector
Pfd	See pF
PFI	Power-fail input
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.
PFO	Power-fail output
PG	Power-good; power gain
PGA	Programmable Gain Amplifier: An amplifier whose gain can be varied by a separate input (usually a digital value). See: Programmable-Gain Amplifier, Using the MAX532 DAC
PGAs	See PGA
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	See 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)
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. From Wikipedia.
PLM	Pad limiting metal
PMIC	Power Management Integrated Circuit: Circuits used to regulate and control power.
PMM	Power-management mode
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. More: Point-of-Load DC-DC Conversion POLs with integrated MOSFETs
POK	Power-OK
POL	See Point-of-Load
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).
pop	See Click-and-Pop
Pop Reduction	See Click/Pop Reduction
pop-noise	See Click-and-Pop
POR	Power-on reset
Positive Temperature Coefficient	See PTC
Pot	See Potentiometer
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 Management Integrated Circuit	See PMIC
Power Supply Rejection Ratio	See PSRR
Power-Fail Comparator	See Power Fail
Power-Over-Ethernet	See PoE
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	See HomePlug
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 (see links below).
Private Mobile Radio	See PMR
PRM	Performance report message
Process Failure Mode and Effects Analysis	See PFMEA
PROCHOT	See PROCHOT#
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
PROM	Programmable read-only memory
PRT	Platinum Resistance Thermometer, a resistance temperature device (RTD).
PRV	See Peak Inverse Voltage
PS	Power sense
PSD	Preamble-switched diversity
PSK	Phase-shift keying (PSK): A modulation technique in which the phase of the carrier conveys the input signal's information.
PSR	Power-supply rejection
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.
PV-S	Picovolt second(s)
PVR	Personal video recorder
PWD	Pulse-width distortion
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.