Electrical Description - Seagate ST15150N - Barracuda 4.3 GB Hard Drive Product Manual

ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D
11.7.3
11.7.3.1
ST15150WC/DC drives
Recommended mating SCA-2 part numbers:
AMP vertical (SCA), 80-position:
787311-1, 3.18 mm tail length with polarization feature
787311-2, 3.18 mm tail length without polarization feature
787311-3, 4.57 mm tail length with polarization feature
787311-4, 4.57 mm tail length without polarization feature

Electrical description

ST15150N and ST15150W drives use single-ended interface signals. These
signals must be terminated with 110 ohm active termination circuits at each
end of the total cable. Single-ended circuits use open collector or three-state
drivers. These models can be configured to provide the SCSI termination.
ST15150ND and ST15150WD drives use differential interface signals. Each
of these signals must be terminated at each end of the total cable with 330
ohms to +5V and 330 ohms to ground with 150 ohms between each
differential pair. All I/O circuits are open collector, three-state drivers.
Differential I/O drives are shipped without terminators and have no provi-
sions for adding terminator sockets on the PCB. You must provide external
termination for these drives.
ST15150WC/DC drives use the single connection attachment (SCA) con-
nector. This 80-pin connector plugs directly into a rack panel in the host
system. No external cables are required. Active termination on the back
panel must be provided. This connector is not recommended where cabling
is required.
Single-ended drivers/receivers
Typical single-ended driver and receiver circuits for the Barracuda 4 family
are shown in Figure 31. Terminator circuits shown are needed only when the
disc drive is first or last on the daisy chain. (See Note 1 following Figure 31.)
Note. All single-ended terminators must be ANSI SCSI-2 alternative 2
active terminators.
Transmitter characteristics
Single-ended drives use an ANSI SCSI compatible open-collector single-
ended driver. This driver is capable of sinking a current of 48 mA with a low-
level output voltage of 0.4V.
Receiver characteristics
Single-ended drives use an ANSI SCSI single-ended receiver with hyster-
esis gate or equivalent as a line receiver.
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