Seagate ST19171WC Product Manual - Page 82
ST19171N and ST19171W drives
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72 Barracuda 9 Product Manual, Rev. C 9.8 Terminator requirements ST19171N and ST19171W drives Internal disc drive I/O termination consists of active circuits contained in an LSI module that is permanently mounted on the PCB. All single initiator/single target (non-daisy-chain) applications require you to terminate the initiator and drive. Terminate both ends of the SCSI bus with ANSI SCSI-2 standard alternative 2 (active) termination. Do not mix active and passive terminators on the same SCSI bus. Daisy-chain configurations require you to terminate only the units at each end of the daisy chain. Do not terminate any other peripherals on the chain. Note. Remove the Enable SCSI Terminator jumper from J2 pins 15 and 16 when terminators are not required. ST19171WC and ST19171DC drives SCA connector drives do not have internal terminators available. You must provide external active terminators when termination is required. ST19171WD drives Differential I/O Barracuda drives do not have internal terminators available. You must provide external active termination when termination is required. 9.9 Terminator power ST19171N and ST19171W drives You can configure terminator power in four different ways. See Section 8.1 for illustrations that show how to place jumpers enabling each of the following terminator power configurations: 1. Drive accepts terminator power through SCSI bus pins: ST19171N Pin 26 ST19171W Pins 17, 18, 51, and 52 2. Drive supplies power to the SCSI bus. 3. Drive provides terminator power for optional internal terminator resistors using the drive's power connector. 4. Drive provides power to its own terminators and to the SCSI bus terminator power line. SCSI devices providing terminator power (TERMPWR) must have the following characteristics: 8-bit SCSI V TERM = 4.25 V to 5.25 V 800 mA minimum source drive capability 1.0 A maximum 16-bit SCSI V TERM = 4.25 V to 5.25 V 1,500 mA minimum source drive capability 3.0 A maximum ST19171WD drives You can configure terminator power from the drive to the SCSI bus or have the host adaptor or other device supply terminator power to the external terminator. See Section 8.1 for illustrations that show how to place jumpers for this configuration. ST19171WC and ST19171DC drives These drives cannot furnish terminator power because no conductors in the 80-pin I/O connector are devoted to terminator power.