Figure 29. Single-Ended Transmitters And Receivers - Seagate ST31250N Product Manual

Barracuda 2LP Product Manual, Rev. D
11.7.3.2
Receiver characteristics
Single-ended drives use an ANSI SCSI single-ended receiver with hyster-
esis gate or equivalent as a line receiver.
Line Driver
Transmitter
[4]
(or transceiver)
[1]
[2]

Figure 29. Single-ended transmitters and receivers

Notes:
[1] Part of active terminator circuits. Enable drive termination when it is first
or last on the daisy chain.
Interface signal levels and logical sense at the drive I/O connector are
defined as follows:
Logic level Driver output
≥ 2.5V : ≤ 5.25V
Negated (0)
≤ 0.4V : ≥ 0.0V
Asserted (1)
The difference in the voltages between input and output signals is due to
losses in the cable.
[2] ANSI SCSI compatible circuits.
[3] Total interface cable length should not exceed that specified in Section
11.7.1.2.1.
[4] Source of drive terminator power is VR1 which has an input source
voltage selected by a jumper.
Differential drivers/receivers
Typical differential driver and receiver circuits used by ST31250ND,
ST31250WD, ST32550ND and ST32550WD drives are shown in Figure 30.
The differential drives have no provisions for terminator circuits.
Differential signals
All differential interface signals consist of two lines denoted +SIGNAL
and –SIGNAL. A signal is true when +SIGNAL is more positive than
–SIGNAL, and a signal is false when –SIGNAL is more positive than
+SIGNAL. Terminate all assigned signals at each end of the cable as
shown in Tables 15, 17 and 19. You must provide external termination for
the differential drives.
Line Receiver
[4]
+2.85V
Flat
110
Cable
[1]
Ohm
Pair
[3]
Receiver input
≥ 2.0V : < 5.25V
≤ 0.8V : > 0.0V
73
Receiver
+2.85V
110
Ohm
[2]