Seagate ST318418N manual Single-ended drivers/receivers for N models, Transmitter characteristics

70 Barracuda 36ES2 Product Manual, Rev. B

9.7.1.1Single-ended drivers/receivers for N models

For “N” models which use single-ended drivers and receivers, typical circuits are shown in Figure 24. Termina- tor 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 24. Single-ended transmitters and receivers on N models

Notes.

[1]Part of active terminator circuits. Non-removable LSI terminators, enabled in the drive (model N 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 14. Applies to N models.

[5]Interface signal levels and logical sense at the drive I/O connector for N models are defined as follows: 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.

9.7.1.2Single-ended drivers/receivers for LW models

The maximum total cable length allowed with drives using single-ended I/O driver and receiver circuits depends on several factors. Table 16 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.