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DS2109DK DS2109DK DS2109 Demo Board The DS2109DK is used in Plug and Play SCSI motherboards and host bus adapters to provide automatic active termination for 18 pairs of signal lines and is available in a 28-pin SOIC package. The DS2109DK is a demo board for both narrow and wide SCSI. A DS21S07AE is used with the DS2109DK to terminate 27 lines for a SCSI-2 or SCSI-3 wide bus. To use as a terminator for a narrow bus, connect the SCSI cable into J2 of the DS2109DK. To use at the end of a wide bus, connect to J1. Test points are available for all of the SCSI bus signals. The TERM PWR LED indicates termination power from the bus. To demonstrate the automatic termination schemes of the DS2109DK, connect cables to both J1 and J2. The SCSI specifications require terminators installed in the middle of the SCSI bus to be powered down or isolated from the bus. The PDO LED will turn on when the DS2109DK is isolated from the SCSI bus. The ground detect method is controlled by switch GND DETECT. Move the switch to YES, and if SCSI devices are installed at both connectors, the PDO LED will come on. The current sense method requires switch CURRENT SENSE to be YES and then swtiching the RESET switch from FLOAT to GND to FLOAT. This imitates a SCSI reset from the host controller. If terminators are connected to J1 and J2, the PDO LED will light. When not demonstrating the automatic termination schemes, leave switches S1 and S2 at NO and switch S3 at FLOAT. MATERIALS USED: PART U1 U2 J1 J2 S1-3 C1 C2, C4 C3, C5 L1-2 Z1 R1-2 DESCRIPTION Plug and Play SCSI Terminator SCSI Active Terminator Wide SCSI connector Narrow SCSI connector Switch 2.2 F/16V tantalum capacitor 4.7 F/10V tantalum capacitor 0.1 F/10V ceramic capacitor SMT Red LED Jlead 350 mW SOT23 2.7V Zener 1/8W 5% 1.2K Resistor SOURCE Dallas Semiconductor Dallas Semiconductor Thomas and Betts Thomas and Betts PM Circuits Inc. Sprague Kemet Kemet Digikey Digikey MEPCO PART NUMBER DS2109S DS21S07AE HFR068RA29BS1 501-5007ES D7789 293-X225X9010A2T T491A475K010AS C1206C103K5RAC P500 BZX84C2V7ZX 9C12063A1201JKR 022698 1/3 DS2109DK DS2109DK LAYOUT PDO LOW YES S1 NO NO YES S2 FLOAT GND L1 S3 Z1 TERM PWR L2 GND DETECT CURRENT SENSE RESET R1 R2 I/O REQ C/D SEL DB0 DB1 DB2 DB3 DB4 DB5 DB6 DB7 J1 C3 J2 C1 TP GND DB8 DBP1 DB9 DB10 DB11 DB13 DB12 C4 U2 DS2109S DB15 DB14 C2 U1 DS2109S MSG RST ACK BSY ATN DBP C5 DS2109DK DEMO DALLAS SEMICONDUCTOR CALL 214-450-8110 FOR INFO 022698 2/3 DS2109DK DS2109DK SCHEMATIC Z1 2.7V C1 2.2 f C2 4.7 f C3 0.1 f C4 4.7 f C5 0.1 f L1 LED R1 R2 1.2K L2 LED J2 U2 DS21507AE U1 DS2109S S2 S3 J1 022698 3/3 |
Price & Availability of DS2109DK
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