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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: A Simple ADC Comparison Matrix Understanding SAR ADCs Understanding Flash ADCs
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	Synchronous Digital Hierarchy: The ITU-TSS International standard for transmitting information over optical fiber.
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	An ADC architecture consisting of a 1-bit ADC and filtering circuitry which over-samples the input signal and performs noise-shaping to achieve a high-resolution digital output. The architecture is relatively inexpensive compared to other ADC architectures.
Sigma Delta Converter	See Sigma Delta
Sigma-Delta	See Sigma Delta
Signal Conditioner	A device placed between a signal source and a readout instrument to change the signal. Examples are attenuators, preamplifiers, charge amplifiers, and sophisticated level-translating deivices that can compensate for non-linearities in the sensor or amplifier.
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.
SNR	See Signal-to-Noise Ratio
Snubber	A device which suppresses voltage transients.
SO	Small outline
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
Source	1. One of the three terminals that comprise a FET. A voltage on the gate controls the current flow between the source and drain. 2. A "voltage source" or "current source" is an idealized generator of voltage or current in a circuit. These sources can be AC or DC, controlled or constant.
SPC	See SQC
SPCR	Service Control Peripheral Register
SPDR	Service Control Data Register
SPDT	See SPST
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	See FHSS
sps	See Samples per Second
SPST	See SPDT
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.
Squelch	A circuit which mutes the signal when it is below a certain level. Typically used to quiet the signal when only noise is present.
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
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 (Delay Lines): 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 and 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.
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 Boost Controller	See DC-DC Controllers
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-DCs
switching amplifier	See Class D
Switching Regulator	See DC-DCs
Switching Supply	See Switching Regulator
SWT	Set watchdog timeout
Synchronous Digital Hierarchy	See SDH
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 Timing and Control	See STC