Glossary Terms and Definitions Beginning with the Letter S

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S 1. Siemen(s), standard unit for conductance

2. Lower case s is the standard abbreviation for seconds.

S Parameters See S-Parameters
S-Parameters The reflection and transmission coefficients used in impedance matching between high-speed (RF) devices and transmission lines/traces.
S-UMTS Satellite-universal mobile telecommunications system
S-video See Y/C
S/N See Signal-to-Noise Ratio
S/N Ratio See Signal-to-Noise Ratio
S/S Single supply
Sample Rate See Sampling Rate
Samples per Second 1. sps: Samples per second. In data conversion, an analog signal is converted to a stream of numbers, each representing the analog signal's amplitude at a moment in time. Each number is called a "sample." The number sample per second is called the sampling rate, measured in samples per second.

2. ksps: Kilosample(s) per second (thousands of samples per second)

3. Msps: Megasamples per second (millions of samples per second)

Also see:

Sampling Rate An A/D converter converts an analog signal into a stream of digital numbers, each representing the analog signal's amplitude at a moment in time. Each number is called a "sample." The number sample per second is called the sampling rate, measured in samples per second.
SAN Storage Area Network: A network infrastructure of shared multihost storage, linking all storage devices and interconnecting remote sites.
SAR Successive Approximation Register: Used to perform the analog-to-digital conversion in successive steps in many analog-to-digital (ADC) converters.
SAW Surface Acoustic Wave: A sound wave that propagates along the surface of a solid and is contained within the solid. SAW devices typically combine compressional and shear components. In Wireless applications, SAW refers to a Surface Acoustic Wave band-pass filter, which exhibits much better out-of-band rejection, but has higher passband ripple and insertion loss.
SAW Filter See SAW
SAW Oscillator See SAW
SB Side braze
SBD See Schottky Diode
SBGA Super ball-grid array, a packaging technology.
SBS Smart Battery Specification: A specification developed by Duracell.
scan chain See Scan Design
Scan Design A design technique in which the internal registers or flip-flops of a circuit can be chained, to allow an external circuit to easily read and write their contents.

When internal memory elements are not directly accessible from the circuit's outside pins, testing is difficult because their state is unknown. With scan design, a signal reconfigures the elements into a "scan chain" and their contents can be read and if desired, altered.

SCART Also known as Euroconnector or Peritel, a 21-pin connector commonly used in Europe to interconnect satellite receivers, television sets, and other audiovisual equipment (e.g. videocassette recorders). A single connector combines audio and video signals. The name comes from "Syndicat des Constructeurs d'Appareils Radiorécepteurs et Téléviseurs."

Peritel is an abbreviation for "péritélévision." Peri is a prefix that means around or surrounding — in this case, it suggests the connection between the television and its electronic environment.

Scattering Parameters See S-Parameters
SCF Switched-capacitor filter
Schottky barrier diode See Schottky Diode
Schottky Diode A diode realized via a "Schottky-barrier junction" -- a metal-semiconductor junction -- rather than the P-N junction used by conventional semiconductor diodes. Schottky diodes are often chosen for their high switching speed and low forward voltage drop.
SCL Serial clock line
SCLK Serial clock
SCR Silicon-controlled rectifier
SCSI Small Computer System Interface (pronounced "scuzzy"), an interface standard for connecting peripheral devices to computers. Hardware components for implementing a SCSI interface include connector ports on computers and cables for connecting peripheral devices to the computer. SCSI is gradually being supplanted by the newer USB and IEEE 1341 standards.
SCSI Bus See SCSI
SCSI Interface See SCSI
SCSI Terminator See SCSI
SCSI2 See SCSI
SCSI3 See SCSI
SCT Single Chip Transceivers: A single IC that includes data communication transmitter and receiver functions.
SCTs See SCT
Scuzzy See SCSI
SD 1. Signal detect: An output that indicates when a signal is present. A form of Signal Strength Indicator.

2. Secure Digital, a media format for nonvolatile external memory. The successor to the "MultiMedia Card" format, or MMC, SD card memories typically operate from 3.3V supplies with modest current requirements. SD memory cards are best known as storage for digital cameras, smart phones, and other consumer electronic devices.

SDA Serial data access
SDH See Synchronous Digital Hierarchy
SDO Serial data out
SDRAM II See DDR Memory
SDTV Standard Definition Television: Digital formats that do not achieve the video quality of HDTV, but are at least equal, or superior to, NTSC pictures. SDTV may have either 4:3 or 16:9 aspect ratios, and includes surround sound. Variations of fps (frames per second), lines of resolution, and other factors of 480p and 480i make up the 12 SDTV formats in the ATSC standard.
Second Harmonic Distortion Second harmonic distortion (HD2): Ratio of second-order harmonic to the input signal (carrier). Often measured as dBc.
Secure Digital See SD
Secure Hash Algorithm See SHA
Secure Hash Standard This standard specifies a Secure Hash Algorithm, SHA-1, for computing a condensed representation of a message or a data file.
Semiconductor 1. A substance that can act as an electrical conductor or insulator depending on chemical alterations or external conditions. Examples are silicon, germanium, and gallium arsenide.

Also called "III-V" materials since semiconductor elements are in groups III and V of the periodic table of chemical elements.

2. An electronic device (e.g. a transistor, diode, or integrated circuit) manufactured from semiconductor materials.

Semiconductor devices control and amplify because a small voltage or current, or a physical stimulus (such as light or pressure), allows the semiconductor to pass or block electrical current. Devices can be fabricated with other capabilities such as passing electric current in only one direction, emitting light, mixing and transforming signals, etc.

Sense Resister See Sense Resistor
Sense Resistor A resistor placed in a current path to allow the current to be measured. The voltage across the sense resistor is proportional to the current that is being measured and an amplifier produces a voltage or current that drives the measurement.
Sense-Resister See Sense Resistor
Sense-Resistor See Sense Resistor
SEPIC Single Ended Primary Inductor Converter: A DC-DC converter topology that acts both as a boost and a buck converter (that is, will step up or down, depending on the input voltage).
SerDes Serialization/deserialization
Serial See Serial Interface
Serial Interface A serial interface (as distinguished from a parallel interface) is one in which data is sent in a single stream of bits, usually on a single wire-plus-ground, wire-pair, or single wireless channel (or two sets, one for each direction). Examples include USB, RS-232, I2C, and 1-Wire.

By contrast, a parallel interface sends several bits at once, on separate wires.

Serial Peripheral Interface See SPI
SFDR Spurious-Free Dynamic Range: A term used to specify A/D and D/A converters (ADCs and DACs).

In ADCs, Spurious-Free Dynamic Range (SFDR) is the ratio of the RMS amplitude of the carrier frequency (maximum signal component) to the RMS value of the next largest noise or harmonic distortion component. SFDR is usually measured in dBc (with respect to the carrier frequency amplitude) or in dBFS (with respect to the ADC's full-scale range).

In DACs, Spurious-Free Dynamic Range (SFDR) is the ratio of the RMS amplitude of the carrier frequency (maximum signal components) to the RMS value of their next largest distortion component. SFDR is usually measured in dBc (with respect to the carrier frequency amplitude) or in dBFS (with respect to the DAC's full-scale range). Depending on the test condition, SFDR is observed within a pre-defined window or to Nyquist.

Also see the Maxim Data Conversion Calculator.

SFF Small Form Factor: An optical module.
SFF-8472 Small Form Factor: Specification for optical modules.
SFP Small Form Factor Pluggable
SFR Special-function register
SHA Secure Hash Algorithm: A message digest algorithm developed by the NSA for use in the Digital Signature standard, FIPS number 186 from NIST. SHA is an improved variant of MD4 producing a 160-bit hash. SHA is one of two message digest algorithms available in IPSEC.
Shannon sampling frequency See Nyquist
SHDN Shutdown. Low-power standby mode.
Shift Register Two or more bistable elements (flip-flops) connected in series. With each tick of the clock, the output of stage n is shifted to stage n+1. Applications include clock or signal delays, delay lines, linear-feedback shift registers.
Shock Sensor An acceleration sensor, generally a piezoelectric type, that can measure high acceleration but cannot measure static g forces.
Shoot-Through Current In a push-pull amplifier stage, one transistor pushes current to the output to drive it toward a positive voltage; a second device pulls down. These are designed so both devices are never fully on, which would effectively short the power supply.

The rush of current that occurs while both devices are on is called the shoot-through current. Events that allow both devices to be on (e.g. circuit faults or a brief moment in the switching cycle) are said to "crowbar" the circuit because of its similarity to a power supply protection circuit of that name.

See: Protection and Isolation products.

Shut Down See Shutdown
Shut-Down See Shutdown
Shutdown A feature of many Maxim ICs, typically controlled via a logic-level input, which dramatically reduces power consumption when the device is not in use.
SI Sampled input
SiGe Silicon Germanium process
Sigma-Delta See Delta-Sigma
Signal Detect See SD
Signal-Invalid O/P Signal invalid output. Indicates when all RS-232 signals to the IC are in the invalid range.
Signal-To-Noise And Distortion Ratio See SINAD
Signal-to-Noise Ratio Signal-to-Noise Ratio, the ratio of the amplitude of the desired signal to the amplitude of noise signals at a given point in time. The larger the number, the better. Usually expressed in dB.
Silicon Germanium See SiGe
Silicon Timed Circuit See STC
SIM Subscriber identity module
SINAD Signal-to-noise and distortion ratio: The RMS value of the sine wave f(IN) (input sine wave for an ADC, reconstructed output sine wave for a DAC) to the RMS value of the converter noise from DC to the Nyquist frequency, including harmonic content. It is typically expressed in dB (decibels).
Single Ended Primary Inductor Converter See SEPIC
Single-Wire Serial Interface See 1-Wire
SLBI System loopback input
SLIC Subscriber-Loop-Interface-Circuit: A telephone line interface.
Small Form Factor See SFF-8472
Small Form Factor Pluggable See SFP
Small Office/Home Office See SOHO
Smart Battery A battery with internal circuitry that provides level of charge status to the host system.
Smart Battery Specification See SBS
Smart Phone A phone with a microprocessor, memory, screen, and built-in modem. The smart phone combines some of the capabilities of a PC in a handset device and typically include Internet connectivity.
Smart Signal Conditioner Signal conditioner that is programmable or has a flexible architecture to allow it to accomplish sophisticated signal transformations and corrections.
Smartphones See Smart Phone
SMBus System Management Bus: A 2-wire serial-interface standard developed by Intel.
SMBus I/F See SMBus
SMD 1. Surface Mount Device (SMD): An electronic component that mounts on the surface of a printed circuit board (as opposed to "through-hole" components which have pins that are inserted into holes). SMDs typically allow more components per square centimeter of PC board, but their scale is such that hand assembly and prototyping may be difficult.

2. Standard Military Drawing (SMD): A U.S. government program for standardized MIL-STD-883 product specifications, to simplify military procurement. Sponsored by the DSCC (Defense Supply Center, Columbus).

SMPS Switch-Mode Power Supply
SMR Specialized Mobile Radio: Indicates the 896MHz to 901MHz band (800MHz band), which uses two paired 25kHz channels, and the 935MHz to 940MHz band (900 MHz band), which uses two paired 12.5kHz channels. Ten 20-channel blocks have been allocated in these frequency bands by the FCC. 900MHz SMR is primarily used for radio dispatch, paging, and wireless data communications.
Sn whiskers See Tin Whiskers
SNR See Signal-to-Noise Ratio
Snubber A device which suppresses voltage transients.
SO Small outline (a package type).
SOC State of change

Also see:

SoC See System on a Chip
Sod's Law See Murphy's Law
Soft Start A feature in some switching power supplies that limits the startup inrush current at initial startup.
Soft-Start See Soft Start
SOHO Small Office/Home Office: Businesses that are either run from home or a from a small office. Software and hardware companies sometimes promote products as suitable for the SOHO market.
SOIC Small outline integrated circuit, a packaging technology.
Solid State A solid state device or circuit is one that relies on semiconductors rather than mechanical or vacuum tube circuits.
SONET Synchronous Optical Network: A North American standard for transmission in synchronous optical networks. It defines a family of rates, formats, interfaces, transport options, and maintenance capabilities. The minimum rate for SDH is 155Mbps.
SOT Small outline transistor
Space Diversity In radio systems, Space Diversity transmits a signal on multiple propagation paths.
SPC Statistical process control
SPCR Service Control Peripheral Register
SPDR Service Control Data Register
SPDT
Single-pole/double-throw switch
A switch with three leads, one of which is common. The common lead can connect to one or the other leads exclusively.
Specialized Mobile Radio See SMR
SPFP Signal power functional part
SPI Serial Peripheral Interface. A 3-wire serial interface developed by Motorola.
SPICE Simulation program with integrated circuit emphasis
Spread Spectrum A technology that modulates a signal over many carrier frequencies at once. This method can be used to make transmissions more secure, reduce interference, and improve bandwidth-sharing.

Spread-spectrum techniques can also be used to reduce electromagnetic interference by dithering the clock frequency so emissions are no longer concentrated at one frequency.

See:

sps See Samples per Second
SPST Single-pole/single-throw switch
Spurious-Free Unwanted frequencies are not present.
Spurious-Free Dynamic Range See SFDR
SQC Statistical quality control: Use of statistical methods to measure and improve the quality of manufacturing processes and products. The term "statistical process control" is often used interchangably.
SR Slew rate
SRAM Static RAM: RAM that does not require a clock to retain its contents.
SRF Self-resonant frequency
SS Soft-start; sample size
SSC Smart signal conditioning
SSOP Shrink small-outline package
Standard Definition Television See SDTV
Standing Wave Ratio See VSWR
Star Ground A pcb layout technique in which all components connect to ground at a single point. The traces make in a "star" pattern, emanating from the central ground.
Star Point A point from which all traces leave in a "star" pattern in pcb layout.
Static RAM See SRAM
statistical process control See SQC
statistical quality control See SQC
STB A "set top box," or STB, is a generic name for an electronic interface between a cable television or satellite signal and video display and recording devices. Typically a box that can be placed atop the television set (hence the name), it can have many functions, including acting as a tuner, decoding digital or analog television signals, removing encryption, and allowing the purchase of pay-per-view channels.

Maxim offers a range of products for STB designers. See: Set-Top Box Solutions page.

STC 1. Silicon Timed Circuit: A circuit that produces a delayed version of the input signal. Also known as a delay line.

Also See: Silicon Timed Circuits: Frequently Asked Questions

2. System Timing and Control: Clock generation and distribution systems and components. May include the means for clock control such as spread-spectrum clock generation for EMI reduction, skew rate control, rate dividers, rate control, width, delay, and phase adjustment.

Also See: System Timing & Control Design Guide (PDF) and the Clock Generation and Distribution product line page.

Step Down DC DC See Buck
Step Down Regulator See Buck
Step Down Switcher See Buck
Step-Down DC DC See Buck
Step-Up DC-DC A switch-mode voltage regulator in which output voltage is higher than its input voltage.

See application note 660, "Regulator topologies for battery-powered systems."
Storage Area Network See SAN
Strobe A pulse used for timing and synchronization.
Subscriber-Loop-Interface-Circuit See SLIC
Successive Approximation Register See SAR
Superheterodyne Receiver A radio receiver that combines a locally generated frequency with the carrier frequency to produce a lower-frequency signal (IF, or intermediate frequency) that is easier to demodulate than the original modulated carrier.
Supervisor See Microprocessor Supervisor
Supervisory See Microprocessor Supervisor
Surface Acoustic Wave See SAW
Surface Acoustic Wave band-pass filter See SAW
surge suppressor See Metal Oxide Varistor
Swallow Counter The Swallow Counter is one of the three building blocks (swallow counter, main counter, and dual-modulus prescaler) that constitute the programmable divider commonly used in modern frequency synthesizers.

The swallow counter is used to control the dual-modulus prescaler which is set to either N or (N+1). At the initial reset state, the prescaler is set to a divide ratio of (N+1), but the swallow counter will change this divide ratio to N when it finishes counting S number of cycles.

The Swallow Counter gets its name from the idea that it "swallows" 1 from (N+1) of the dual-modulus prescaler.

SWAP Shared wireless access protocol
Switch See Analog Switch
Switch Debouncer See Debounce
Switch Mode Uses a switching transistor and inductor to control/regulate the charging voltage/current.
Switch Mode Controller See DC-DC Controller
Switch-Mode Power Supply See SMPS
Switched Cap See Switched Capacitor Circuit
Switched Capacitor Circuit A circuit methodology, typically implemented in CMOS integrated circuits, that uses clocked switches and capacitors to transfer charge from node to node such that a resistor function is realized. The effective resistance is governed by capacitor size and switching clock frequency.
Switched Capacitor Converter See Charge Pump
Switcher See DC-DC
switching amplifier See Class D
Switching Regulator A voltage regulator that uses a switching element to transform the supply into an alternating current, which is then converted to a different voltage using capacitors, inductors, and other elements, then converted back to DC. The circuit includes regulation and filtering components to insure a steady output. Advantages include the ability to generate voltages beyond the input supply range and efficiency; disadvantages include complexity.

See: Switching Regulator Applications

See: DC-DC Converter Tutorial

SWR See VSWR
SWT Set watchdog timeout
Synchronous Digital Hierarchy Synchronous Digital Hierarchy, SDH: The ITU-TSS International standard for transmitting information over optical fiber.
Synchronous Optical Network See SONET
Synchronous Rectification In switch-mode power supplies, the "steering" diode is replaced or paralleled with a FET switch to reduce losses and thereby increase efficiency. The FET is off during the inductor charge cycle, and then turned on as the inductor discharges into the load.
Synchronous Rectifier See Synchronous Rectification
System Management Bus See SMBus
System on a Chip A System on a Chip (SoC) integrates most of a system's elements on a single integrated circuit (chip). It typically combines a microprocessor core along with interface elements and analog and mixed signal functions.
System Timing and Control See STC