FT ROAMASEIORS Terminators Waar is A Tessonarorn? A terminator is a device which terminates the end of a signal line. Terminators can be internal to the system, or they can be in a separate configuration known as a TERMINATOR". This is the preferred configuration for expandable bus systems due to its versatility. Physically, terminators are connectors with a resistor network or a resistor and current-voltage regulation network encased in a protective overmold or shell assembly. Wry Use A Tesninarar? SCSI terminators have two basic functions; 1) establish the proper voltage and current for signal line operation; 2) match the line impedance and reduce reflection. 1. A terminator is an important working partner for a driver. When a driver pulls down the signal, a voltage low (true state) terminator supplies proper current to maintain the voltage level and when a driver pulls up the signal voltage high (negate), a terminator helps a driver make a quick and smocth negation. 2. Termination is needed at the two ends of the SCSI bus. The impedance mismatches are generally of greatest magnitude at the ends of the bus. A terminator matches a bus characteristic impedance and minimizes the reflection. GENERAL Types of TERMINATION There are two general methods of accomplishing termination: passive and active. Passive termination systems make use of fixed value resistors that place a matching resistance at the end of each signal line. This method is satisfactory for many applications. However, as signal speeds increase INTRODUCTION TO TERM and noise margins decrease, passive termination may no longer assure a reliable signal transmission. Active termination is the solution to this challenge. It reacts to an active negation driver and helps to make a clean monotonic wave shape in a high speed signal transfer by abilities of sourcing and sinking current and protecting a system by limiting maximum current. GENERAL COMFIQURATION OF TEAMINSTORS Terminators are available in two general configurations: feedthrough and end-of-line. A feedthrough termination typically installs between an equipment I/O port and a ribbon cable bus connector. This permits a quick and simplitied change in peripheral devices within an existing system configuration. This type of configuration is used if there is no INATORS provision for a pluggable terminator. Although these terminators generally appear as devices with an input and output port, they may also have no ports, in which case they are crimped directly to the cable. End-of-line terminators are installed at the end of a line, and do not continue the bus. The devise using this type of terminator must have both an input and output port. In addition, terminators may be of a shielded or unshielded construction. Shielded terminators are generally required when a bus in used between equipment cabinets. An unshielded terminator, conversely, is intended for use within an equipment cabinet. Thomas & Betis Electronics/OEM Division Tel: 901-682-7766 Fax: 901-680-5200 165 FT ROAMASEIORS Terminators FINE-PITCH IDC INLINE UNSHIELDED TERMINATORS (FPSL SERIES) Gg w Byygican Paorgarigs INSULATION MATERIAL: Thermoplastic rated UL 94V.0. Contacts: Copper alloy; Tin-lead over nickel plating overall. ELECTHICAL PROPERTIES Wattace Ratina: 1/8 Watt 377 REF MaxiMuM OPERATING VOLTAGE: 50 volts ENVIRONMENTAL PRopeaTies TEMPERATURE RATING: OG to 70C (9.58) CONFIGURSTION. Internal, end-of-line, unshielded APELICATION: SCSI-2 and SCSI-3 systems. Should be used in application within an enclosure. INSTALLATION Toon Son Suauine fig? TERMINATOR: 254 [6.45} ies 370 779-TRM68 [9.40] Recoumsenoes Cases 425 [10.80] 126-068 137-068 140-068 141-068 RMos8EPSLDI RMO6SEPSLAN wt Phere tot Patt C1 21 23 25 27 2931 fi 37 39.41 43 45 47 49 51 63 565 S7 59 G1 G3 65 67 Att 1.000 REF DETAIL A | 330 OHM TYP { 159 OHM | it 4. | Peeper ay 121416 18 20 22 24 26 28/30 32 : ISPPrry yr SCHOTTKY RECTIFIER R-TRMPWR TERM PWR BUS Differential PEt 436 38 40 42.44 46 43 50 52 54 56 58 60 62 64 66 Gd 4.3840 REF [46.74] PRE-LATCH 4244 [31.60] eA. LATCHED 1164 [29.57} 1.962 [49.83] Mh sl 025 PITCH (63. ENE PITCH IDC SCSI 205 LUNDLO Ck RIBS R Active Negation Thomas & Betis Electronics/OEM Division Tel: 901-682-7766 Fax: 901-680-5200 172 Dimensions shown are for reference only. Dimensions are in millimeters (inches).