Seagate ST11200N Product Manual page 74

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11.6.4.3 Terminator requirements
Internal disc drive I/O termination (provided only in single ended I/O drives) consists of active circuits with
resistor modules that plug into sockets on the Main PCB (see Figure 11.6-1). The disc drive models that
offer internal terminator sockets may be ordered with or without the resistor modules to facilitate a particular
application. All single initiator/single target (nondaisychain) applications require that the Initiator and disc
drive be terminated. Daisychain applications require that only the units at each end of the daisychain be
terminated. All other peripherals on the chain should not be terminated. (See Figure 11.6.2-1).
Note. Remove terminator resistor modules where terminators are not required. Removal of terminator
power source selection jumper (see Figure 10.1-1) does not disconnect the terminator resistors
from the circuit.
For the Single-ended I/O ST11200N/NC applications, the SCSI bus MUST be terminated at both ends with
ANSI SCSI-2 Standard's Alternative 2 termination (active termination), especially if the bus will be operated
at FAST SCSI transfer rates. The ST11200N/NC provides active termination as the on-board termination
option.
Note. ALL TERMINATORS USED IN THE DAISYCHAIN ABSOLUTELY MUST BE ACTIVE TERMINA-
TORS AS DESCRIBED ABOVE.
Differential I/O ST11200ND does not have provisions to add terminator sockets on the PCB. The user or
systems integrator must provide a terminator arrangement external to the drive.
11.6.4.4 Terminator power
The drive may be configured to accept terminator power via pin 26 of the SCSI Bus, to supply power to the
SCSI bus or to provide terminator power for optional internal termination resistors via the drive power
connector. See Figure 11.6-1 and 10.1-1. The drive can provide power both to its own terminators and to the
SCSI Bus terminator power line (Pin 26).
SCSI devices providing terminator power (TERMPWR)* shall have the following characteristics:
*See Figure 10.1-1 for configuration details.
Product Manual - Hawk 1 Family SCSI-2 (Volume 1), Rev. D
V TERM = 4.50 V to 5.25 V
800 mA min source drive capability
1.0 A maximum