Seagate Barracuda 36ES ST318417N, Руководство по эксплуатации продукта

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80 Barracuda 36ES Product Manual, Rev. H
9.7.1.1 Single-ended drivers/receivers for N and W models
For “N” and “W” models which use single-ended drivers and receivers, typical circuits are shown in Figure 31.
Terminator circuits (see Note [1]) are to be enabled only when the disc drive is first or last in the daisy-chain.
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 0.4 volt.
Receiver characteristics
Single-ended drives use an ANSI SCSI single-ended receiver with hysteresis gate or equivalent as a line
receiver.
Figure 31. Single-ended transmitters and receivers on N and W models
Notes.
[1] Part of active terminator circuits. Non-removable LSI terminators, enabled in the drive (models N and W
only) with jumper plug
TE when it is first of last in the daisy-chain.
[2] ANSI SCSI compatible circuits.
[3] Total interface cable length should not exceed that specified in ANSI Standard T10/1302D.
[4] Source of drive terminator power is an active circuit which has an input source voltage selected by jumper
plug
TP . See Figure 19. Applies to N and W models.
[5] Interface signal levels and logical sense at the drive I/O connector for N and W models are defined as fol-
lows:
Vil (low-level input voltage) = 1.0 V maximum (signal true); minimum = Vss – 0.5 V.
Vih (high-level input voltage) = 1.9 V minimum (signal false); maximum = Vdd +0.5V.
Vihys (Input Hysteresis) = 425 mV minimum
See ANSI Standard T10/1302D (SPI-3) for detailed electrical specifications.
9.7.1.2 Single-ended drivers/receivers for LC and LW models
Note. LC models use the single connection attachment (SCA) connector. This connector is designed to plug
directly into a back panel or plane. No external cables are required. Active terminators on the back
panel must be provided by the user. This connector is not recommended where cabling is required.
The maximum total cable length allowed with drives using single-ended I/O driver and receiver circuits
depends on several factors. Table 19 lists the maximum lengths allowed for different configurations of drive
usage. These values are from the SPI-3 document. All device I/O lines must have equal to or less than 25 pf
capacitance to ground, measured at the beginning of the stub.
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