Barracuda 18LP Family: ST39175LW/LC ST318275LW ... - Seagate
Barracuda 18LP Family: ST39175LW/LC ST318275LW ... - Seagate
Barracuda 18LP Family: ST39175LW/LC ST318275LW ... - Seagate
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<strong>Barracuda</strong> <strong>18LP</strong> Product Manual, Rev. E 67<br />
9.8 Terminator requirements<br />
All single initiator/single target (non-daisy-chain) applications require that the Initiator and disc drive be terminated.<br />
Daisy-chain applications require that only the units at each end of the daisy-chain be terminated. All<br />
other peripherals on the chain must not be terminated (see Figure 10).<br />
It is required that ANSI SCSI-2 Standard’s Alternative 2 termination (active termination) be used for applications<br />
with single-ended mode, especially if the bus will be operated at transfer rates above 5 Mbytes/sec.<br />
Note. ACTIVE TERMINATORS ARE REQUIRED FOR USE IN THE DAISY CHAIN AS DESCRIBED<br />
ABOVE. PASSIVE TERMINATORS SHALL NOT BE USED AT ANY TRANSFER SPEED. ACTIVE<br />
AND PASSIVE TERMINATORS SHALL NOT BE MIXED ON THE SAME SCSI BUS.<br />
Drive models “LW” and “<strong>LC</strong>” do not have internal terminators available. The user, systems integrator or host<br />
equipment manufacturer must provide a terminator arrangement external to the drive. For “LW” models, terminator<br />
modules can be purchased that plug between the SCSI I/O cable and the drive I/O connector or on the<br />
end of a short I/O cable stub extending past the last cable connector.<br />
ANSI Standard X3T10/1143D contains additional details about SCSI bus terminator and terminator power<br />
requirements.<br />
9.9 Terminator power<br />
“LW” model drives<br />
You can configure terminator power in two different ways. See Section 8.1 for illustrations that show how to<br />
place jumpers enabling each of the following terminator power configurations:<br />
1. The external terminator accepts terminator power through SCSI bus pins 17, 18, 51, and 52.<br />
2. Drive supplies terminator power to the SCSI bus on pins 17, 18, 51, and 52.<br />
SCSI devices providing terminator power (TERMPWR) must have the following characteristics:<br />
8-bit SCSI V TERM = 4.25 V to 5.25 V<br />
800 mA minimum source drive capability<br />
1.0 A maximum<br />
16-bit SCSI V TERM = 4.25 V to 5.25 V<br />
1,500 mA minimum source drive capability<br />
3.0 A maximum<br />
“<strong>LC</strong>” model drives<br />
These drives cannot furnish terminator power because no conductors in the 80-pin I/O connector are devoted<br />
to terminator power.
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