Seagate ST15150DC, Product Manual

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74 ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D
11.7.3.3 Terminator requirements
ST15150N drives
Internal disc drive I/O termination consists of active circuits contained in
permanently mounted IC terminator packs on the main PCB. All single
initiator/single target (non-daisy-chain) applications require you to terminate
the initiator and drive.
Note. Remove the Enable Drive Terminator jumper on J01 pins 1 and 2
when terminators are not required. Removing the terminator power
source jumper does not disconnect the terminator resistors from the
circuit.
You must terminate both ends of the SCSI bus with ANSI SCSI-2 standard
alternative 2 (active) termination, especially if the bus operates at fast SCSI
transfer rates.
Daisy-chain configurations require you to terminate only the units at each
end of the daisy chain. Do not terminate any other peripheral on the chain.
ST15150ND/WD/DC drives
Differential I/O Barracuda drives do not have provisions to add terminator
sockets on the PCB. You must provide external termination.
ST15150W drives
Internal disc drive I/O termination consists of active circuits contained in
permanently mounted IC terminator packs on the main PCB. All single
initiator/single target (non-daisy-chain) applications require you to terminate
the initiator and drive.
Daisy-chain configurations require you to terminate only the units at each
end of the daisy chain. Do not terminate any other peripheral on the chain.
Note. Remove the Enable Drive Terminator jumper on J4 pins 11 and 12
when terminators are not required. Removing the terminator power
source jumper does not disconnect the terminator resistors from the
circuit.
ST15150WC drives
This model does not have provisions to add terminators on the PCB. You
must provide external termination.
11.7.3.4 Terminator power
ST15150N/ND drives may be configured to accept terminator power using
pin 26 of the SCSI bus, to supply power to the SCSI bus, or to provide
terminator power for optional internal terminating resistors using the drive’s
power connector (see Figure 20). ST15150W/WD drives may be configured
as stated above but using pins 17, 18, 51, and 52 (see Figure 22). The drive
can provide power both to its own terminators and to the SCSI bus terminator
power line.
SCSI devices providing terminator power (TERMPWR) must have the
following characteristics:
• V TERM = 4.50V to 5.25V
• 800 mA minimum source drive capability
• 1.0A maximum